Durable graphene oxide membranes

Abstract

To provide durable graphene oxide membranes for fluid filtration.SOLUTION: For example, the graphene oxide membranes can be durable under high temperature non-neutral pH, and / or high pressures. One aspect of the present disclosure relates to a filtration apparatus comprising: a support substrate; and a graphene oxide membrane disposed on the support substrate. The graphene oxide membrane has a first lactose rejection rate of at least 50% with a first 1-wt.% lactose solution at room temperature. The graphene oxide membrane has a second lactose rejection rate of at least 50% with a second 1-wt.% lactose solution at room temperature after the graphene oxide membrane is brought into contact with a solution that is at least 80°C for a period of time.SELECTED DRAWING: None

Description

[Technical field]

[0001] Related Applications This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62 / 848,014, filed May 15, 2019, and U.S. Provisional Patent Application No. 62 / 910,789, filed October 4, 2019, the disclosures of each of which are incorporated by reference in their entireties herein.

[0002] The present disclosure relates generally to graphene oxide membranes and their use in separation processes. [Background technology]

[0003] Membranes can be used to separate mixtures by passing some components (filtrate or permeate) and preferentially retaining others, which are the remainder of the mixture (rejects), according to any of various properties of the membrane and / or various properties of the components of the material being filtered. For example, membranes can be configured to separate the reject from the filtrate based on size exclusion (i.e., physical barriers such as pores that are smaller than the particles being rejected). Other examples include membranes configured to separate the reject from the filtrate based on chemical, electrochemical, and / or physical binding with one or more components of the material being filtered.

[0004] Polymeric membranes are a common type of membrane. They have been used commercially for water softening, desalination, and concentration, removal and purification of various salts, small molecules and macromolecules. However, in certain environments (e.g., oxidizing conditions, high pH, ​​high temperature, or some solvents), polymeric membranes may be damaged or broken due to swelling, oxidation reactions, deterioration, or softening of the polymer. Therefore, there is a need in the art for new membranes that address one or more of the deficiencies of polymeric membranes. Summary of the Invention

[0005] FIELD OF THE DISCLOSURE Embodiments described herein relate generally to durable graphene oxide membranes for fluid filtration. For example, the graphene oxide membranes can be used for the concentration, removal, and purification of various salts.

[0006] One aspect of the disclosure relates to a filtration device including a support substrate and a graphene oxide membrane disposed on the support substrate. The graphene oxide membrane includes a plurality of graphene oxide sheets, each of which is covalently bonded to a chemical spacer, and each of which is not covalently cross-linked to an adjacent graphene oxide sheet. The graphene oxide membrane has a first lactose rejection of at least 50% using a first 1 wt% lactose solution at room temperature. The graphene oxide membrane has a second lactose rejection of at least 50% using a second 1 wt% lactose solution at room temperature after contacting the graphene oxide membrane with a solution that is at least 80° C. for a period of time.

[0007] In some embodiments, the second lactose rejection is substantially the same as the first lactose rejection.

[0008] In some embodiments, the second lactose rejection is greater than the first lactose rejection.

[0009] In some embodiments, the first lactose rejection is 90% or less.

[0010] In some embodiments, the second lactose rejection is 90% or less.

[0011] In some embodiments, the chemical spacer comprises an amine or a derivative thereof. In some embodiments, the chemical spacer comprises -NH-R 1 wherein R 1 is an optionally substituted aryl. In some embodiments, the amine is 4-aminophenylacetic acid or 2-(4-aminophenyl)ethanol.

[0012] In some embodiments, the chemical spacer comprises an amide or a derivative thereof. In some embodiments, the chemical spacer comprises -NH-C(O)-R 2 wherein R 2 are each optionally replaceable C 1 ~C 6 Alkyl or C 2 ~C 6 alkenyl. In some embodiments, the amide is acrylamide, propionamide, isobutyramide, or pivalamide.

[0013] In some embodiments, the solution has a pH of about 7.

[0014] In some embodiments, the solution has a pH of about 11.

[0015] In some embodiments, the solution has a pH of about 14.

[0016] In some embodiments, the solution is a phosphate buffer. In some embodiments, the phosphate buffer is Na 2 HPO 4 Includes.

[0017] In some embodiments, the room temperature is about 20°C.

[0018] In some embodiments, the solution is passed through a graphene oxide membrane.

[0019] In some embodiments, the period of time is about 2 to 6 hours.

[0020] One aspect of the disclosure relates to a filtration device including a support substrate and a graphene oxide membrane disposed on the support substrate. The graphene oxide membrane includes a plurality of graphene oxide sheets, each of which is covalently bonded to a chemical spacer. The graphene oxide membrane has a first lactose rejection of at least 50% using a first 1 wt% lactose solution at room temperature. The graphene oxide membrane has a second lactose rejection of at least 50% using a second 1 wt% lactose solution at room temperature after contacting the graphene oxide membrane with a pH of at least 11 for a period of time.

[0021] In some embodiments, the solution has a pH of at least about 12. In some embodiments, the solution has a pH of at least about 14.

[0022] In some embodiments, the second lactose rejection is substantially the same as the first lactose rejection.

[0023] In some embodiments, the second lactose rejection is greater than the first lactose rejection.

[0024] In some embodiments, the first lactose rejection is 90% or less.

[0025] In some embodiments, the second lactose rejection is 90% or less.

[0026] In some embodiments, the chemical spacer comprises an amine or a derivative thereof. In some embodiments, the chemical spacer comprises -NH-R 1 wherein R 1 is an optionally substituted aryl. In some embodiments, the amine is 4-aminophenylacetic acid or 2-(4-aminophenyl)ethanol.

[0027] In some embodiments, the chemical spacer comprises an amide or a derivative thereof. In some embodiments, the chemical spacer comprises -NH-C(O)-R 2wherein R 2 are each optionally replaceable C 1 ~C 6 Alkyl or C 2 ~C 6 alkenyl. In some embodiments, the amide is acrylamide, propionamide, isobutyramide, or pivalamide.

[0028] In some embodiments, the solution comprises Na 2 HPO 4 Includes.

[0029] In some embodiments, the room temperature is about 20°C.

[0030] In some embodiments, the solution is passed through a graphene oxide membrane.

[0031] In some embodiments, the solution is a buffered solution.

[0032] In some embodiments, the period of time is about 2 to 6 hours.

[0033] One aspect of the present disclosure relates to a filtration device including a support substrate, the support substrate having a thickness of at least about 150 μm and a Young's modulus of at least about 0.9 GPa; and a graphene oxide membrane disposed on the support substrate, the graphene oxide membrane comprising a plurality of graphene oxide sheets, each of the graphene oxide sheets being covalently bonded to a chemical spacer, the graphene oxide membrane having a first lactose rejection of at least 50% using a first 1 wt % lactose solution at room temperature, and after subjecting the graphene oxide membrane to a pressure of about 1000 psi for a period of time, the graphene oxide membrane having a second lactose rejection of at least 50% using a second 1 wt % lactose solution at room temperature.

[0034] In some embodiments, the supporting substrate has a thickness of about 500 μm or less.

[0035] In some embodiments, the supporting substrate has a Young's modulus of about 2.5 GPa or less.

[0036] In some embodiments, the support substrate comprises polypropylene, polyolefin, polyethersulfone (PES), polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN), nylon, or a combination thereof.

[0037] One aspect of the present disclosure relates to a method of treating black liquor, wherein the black liquor is passed through any one of the aforementioned filtration devices, the black liquor comprising lignin, sodium sulfate, sodium carbonate, sodium hydrosulfide, sodium thiosulfate, and / or sodium hydroxide.

[0038] In some embodiments, at least a portion of the lignin is blocked by the graphene oxide film. In some embodiments, at least 50% of the lignin is blocked by the graphene oxide film. In some embodiments, at least 90% of the lignin is blocked by the graphene oxide film.

[0039] In some embodiments, at least a portion of the sodium sulfate is absorbed by the graphene oxide film. In some embodiments, at least 50% of the sodium sulfate is rejected by the graphene oxide film. In some embodiments, at least 90% of the sodium sulfate is rejected by the graphene oxide film.

[0040] In some embodiments, at least a portion of the sodium carbonate is blocked by the graphene oxide film. In some embodiments, at least 50% of the sodium carbonate is blocked by the graphene oxide film. In some embodiments, at least 90% of the sodium carbonate is blocked by the graphene oxide film.

[0041] In some embodiments, at least a portion of the sodium hydrosulfide is blocked by the graphene oxide membrane. In some embodiments, at least 50% of the sodium hydrosulfide is blocked by the graphene oxide membrane. In some embodiments, at least 90% of the sodium hydrosulfide is blocked by the graphene oxide membrane.

[0042] In some embodiments, at least a portion of the sodium thiosulfate is rejected by the graphene oxide membrane. In some embodiments, at least 50% of the sodium thiosulfate is rejected by the graphene oxide membrane. In some embodiments, at least 90% of the sodium thiosulfate is rejected by the graphene oxide membrane.

[0043] In some embodiments, at least a portion of the sodium hydroxide is rejected by the graphene oxide membrane. In some embodiments, at least 50% of the sodium hydroxide is rejected by the graphene oxide membrane. In some embodiments, at least 90% of the sodium hydroxide is rejected by the graphene oxide membrane.

[0044] One aspect of the present disclosure relates to a method of increasing the flux of a graphene oxide film described herein, the method comprising contacting the graphene oxide film with a solution that is at least about 50° C. for a period of time, wherein after the contacting step, the flux is increased by at least 50%.

[0045] Another aspect of the present disclosure relates to a method of increasing the flux of a graphene oxide film described herein, the method comprising contacting the graphene oxide film with a solution having a pH of at least about 10 for a period of time, wherein after the contacting step, the flux is increased by at least 50%. [Brief description of the drawings]

[0046] [Figure 1] FIG. 1 is a schematic diagram of a graphene oxide film according to some embodiments of the present disclosure. [Diagram 2-7](FIG. 2A-FIG. 2F) An example of a one-step reaction between graphene oxide sheets and a chemical spacer. [Figure 8] Modeling diagram to model membrane systems of any size with simple diagrams of permeability and rejection from dead ends or crossflow. All constituent species are tracked. Counter ions (e.g. sodium) are given the same rejection as their paired ion (e.g. Na paired with lignin, Na paired with Cl, Na paired with SO4, etc.). (Total or species influx)*a*t=2*(flux through membrane)*dx*t+(efflux)*a*t. [Figure 9] 1 is a graph showing simulation results for a divalent salt rejection coefficient of 1.0, a module system size of 750, and an operating pressure of 1000 psi. Each series of dots represents a different feed concentration. Some mills will have a more or less concentrated feed. [Figure 10-30] (FIGS. 5A-9E) Graphs showing simulated permeate total dissolved solids (perm TDS) recovery percentage (expressed as recovery ratio) for different system sizes. Each set of dots represents a different feed concentration. These figures show that a sufficiently clean warm water stream can be produced by the graphene oxide membrane. The multi-pass method means that the permeate from a first membrane system passes through a second membrane system. In this case, the recovery is defined by the percentage of the feed of the first system that becomes the permeate from the second system. [Figure 10-13] 5A-5D are graphs showing simulation results for the effect of divalent inhibition at 1000 psi in a single pass regime. [Figure 14-17] 6A-6D are graphs showing simulation results of the effect of pressure at high rejection in a single pass regime. [Figure 18-21] 7A-7D are graphs showing simulation results for system size in a single-pass system. [Figure 22-25]8A-8D are graphs showing simulation results of the effect of blocking in a two-pass scheme. [Figure 26-30] 9A-9E are graphs showing simulation results for multi-pass sizing. [Diagram 31] 1 is a graph showing the UV / Vis ratio versus pH of graphene oxide dispersions. [Diagram 32] Figure 1 shows the rejection of sugar (lactose) and salt (MgSO4) for membranes functionalized with various concentrations of propionamide and various pH. Graphene oxide membranes cast from graphene oxide dispersions at pH 11 are superior to those cast at lower pH, regardless of propionamide concentration. [Diagram 33] Figure 1 shows a graph of tangential flow tests run for >4 weeks under numerous conditions. First, performance is benchmarked against 1 wt% lactose and 0.1 wt% MgSO4 solutions. The first two shaded areas from the left represent exposure to partial phosphate buffer solutions at pH 11.5, temperatures between 65-80°C, and pressures between 700-1000 psi. Small molecule rejection, plotted on the y-axis, does not decrease with exposure to increasing pH. The third shaded area from the left represents a switch from lactose feed to a synthetic weak black liquor (SWBL) feed, which allows for continuous runs at high temperature, pressure, and high pH (pH=13). Constant performance is observed in terms of small molecule rejection (y-axis) as conditions vary between high pressure (third shaded area from the left) and high temperature (fourth shaded area from the left). The SWBL contains 1 wt% pyrogallol, 0.1 wt% Na2SO4, 0.61 wt% NaOH, and 0.4 wt% KCl. To produce the SWBL, KCl and sodium hydroxide are added to milli-Q water, and then pyrogallol and Na2SO4 are added sequentially to the mixture. [Figure 34-37](FIG. 13A-D) Graphs showing the effect of pH on the color of graphene oxide films, which can indicate the stability of the films. The color change can be quantified by converting the red / green / blue (RGB) images to grayscale using image processing software and comparing the grayscale mode values ​​of the resulting signals. For the four films at pH 7-13, the histograms below each image show the distribution of gray values ​​for each image, with the x-axis representing the possible gray values ​​(0-255) and the y-axis representing the number of pixels seen at each gray value. Grayscale mode values ​​closer to zero correspond to darker images. Conversely, grayscale mode values ​​closer to 255 correspond to lighter images. FIGS. 13A-13D show a mode shift from a grayscale mode value of 174 (lightest) for the pH 7 sample to a grayscale mode value of 127 (darkest) for the pH 13 sample, indicating that pH has a quantifiable effect on color. [Figure 38-39] (FIGS. 14A-14D) Graphs showing the effect of temperature on the color of graphene oxide films. Films exposed to a combination of pH 11.5 and 80° C. shift the mode from 64 (before) to 29 (after). Films exposed to 50° C. at approximately pH 7 showed negligible mode change from 57 (before) to 56 (after). [Figure 40-47] (FIG. 15A-H) A series of photographs and graphs showing the stability of graphene oxide films exposed to partial phosphate buffer at 80° C. and pH 11.5, which have pivalamide as a chemical spacer. The grayscale mode values ​​are similar from the 4 hour time point to the 7 day time point. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] Graphite is a crystalline form of carbon in which atoms are arranged in a hexagonal structure layered in a series of planes. Due to its abundance on Earth, graphite is very inexpensive and is commonly used in pencils and lubricants. Graphene is a monolayer of carbon atoms (i.e., one of the layers of graphite) that has some excellent electrical, mechanical, optical, and electrochemical properties, earning it the nickname "wonder material." Graphene is highly transparent, extremely light, flexible yet robust, and an excellent electrical and thermal conductor, just to name a few. Such extraordinary properties make graphene and related thin-layer graphitic materials (e.g., few-layer graphene) promising candidates for a variety of applications. For example, graphene can be used in coatings to prevent oxidation of steel and aluminum, and to filter salt, heavy metals, and oil from water.

[0048] Graphene oxide is an oxidized form of graphene with oxygen-containing pendant functional groups (e.g., epoxide, carboxylic acid, or hydroxyl) that exist in the form of sheets of a single atom thickness. Graphene oxide sheets can be produced by oxidizing the graphene in graphite. For example, graphene oxide sheets can be prepared from graphite using a modified Hummers method. Flake graphite can be oxidized by the addition of KMnO 4 , H 2 SO 4 , and / or NaNO 3 The graphene oxide particles are then oxidized in a mixture of 1,0 ...

[0049] Graphene oxide has been explored for use in membranes for filtration applications due in part to its low cost, high chemical stability, strong hydrophilicity, and compatibility with various environments. For example, compared to polymeric membranes that are prone to oxidation, graphene oxide membranes can remain stable when exposed to oxidative conditions. However, existing graphene oxide membranes suffer from durability issues when exposed to high temperatures or acidic / basic conditions. For example, some existing graphene oxide membranes can achieve high lactose rejection (e.g., at least 50%) with a 1 wt% lactose solution at room temperature immediately after fabrication. However, the performance of these graphene oxide membranes decreases after exposure to high temperatures (e.g., above about 50° C.) and / or non-neutral pH environments (e.g., pH=11) for a period of time. The lactose rejection at room temperature by these graphene oxide membranes can decrease to 30%, 20%, or even less after exposure to these conditions, thereby rendering these graphene oxide membranes ineffective for certain filtration applications. In contrast, the present disclosure provides graphene oxide membranes that have at least 50% rejection using a 1 wt % lactose solution, and can have at least 50% rejection using a 1 wt % lactose solution after exposure to elevated temperatures and / or non-neutral pH environments.

[0050] Thus, the present disclosure provides graphene oxide membranes that have one or more properties superior to existing graphene oxide membranes. By at least tailoring the chemicals covalently bonded to each of the graphene oxide sheets, the present disclosure provides graphene oxide membranes that are temperature, pH, and / or pressure durable. Surprisingly, the present inventors have found that graphene oxide membranes that are temperature, pH, and / or pressure durable can be fabricated by cross-linking the graphene oxide sheets. They discovered that it is possible to manufacture the material without

[0051] As shown in FIG. 1 , one embodiment of the present disclosure provides a graphene oxide film 100 including a plurality of graphene oxide sheets 110 and a plurality of chemical spacers 120, wherein each of the graphene oxide sheets 110 is not covalently cross-linked to an adjacent graphene oxide sheet 110.

[0052] In some embodiments, the graphene oxide sheets 110 may be generally arranged and oriented parallel to one another.

[0053] The spacing between the graphene oxide sheets 110 can be either interlayer spacing or intralayer spacing. The spacing between the graphene oxide sheets 110 can be designed to control the molecular weight cutoff of the graphene oxide film 100.

[0054] In some embodiments, the chemical spacer 120 can form a covalent bond with an oxygen-containing functional group on the graphene oxide sheet 110. For example, the chemical spacer 120 can form a covalent bond with an epoxide group, a carboxyl group, or a hydroxyl group on the graphene oxide sheet. In some embodiments, the chemical spacer 120 can also form a covalent bond with a non-oxygen-containing group (e.g., an amine) on the graphene oxide sheet 110. In some embodiments, the chemical spacer 120 can also form a covalent bond with a carbon atom on the graphene oxide sheet 110.

[0055] In some embodiments, the chemical spacer 120 can form non-covalent interactions with adjacent graphene oxide sheets 110 through various mechanisms. In some embodiments, the chemical spacer 120 can be bonded to adjacent graphene oxide sheets 110 through ionic interactions. In some embodiments, the chemical spacer 120 can be bonded to adjacent graphene oxide sheets 110 through hydrogen bonds. In some embodiments, the chemical spacer 120 can be bonded to adjacent graphene oxide sheets 110 through one or more van der Waals forces. In some embodiments, the chemical spacer 120 can be bonded to adjacent graphene oxide sheets 110 through one or more pi effects. In some embodiments, the chemical spacer 120 can be bonded to adjacent graphene oxide sheets 110 through hydrophobic effects.

[0056] In some embodiments, the chemical spacer 120 may include an amine or a derivative thereof. In some embodiments, the chemical spacer 120 may have a structure according to Formula I: -NH-R 1 (I), In the formula, R 1 is aryl or heteroaryl, which may be optionally substituted with one or more substituents. In some embodiments, the substituent is 1 ~C 6 Alkyl and C(=O)OR 1a wherein alkyl is selected from halogen, OH, NH 2 , and optionally substituted by SH, R 1a is H or C 1 ~C 6 In some embodiments, the aryl is phenyl. In some embodiments, R 1 teeth, [ka] where: [ka] indicates the point of attachment to --NH of formula I.

[0057] In some embodiments, the chemical spacer 120 can include 4-aminophenylacetic acid, 2-(4-aminophenyl)ethanol, 2-(4-aminophenyl)propanol, 2-(4-aminophenyl)butanol, or any combination thereof.

[0058] In some embodiments, the chemical spacer 120 may include an amide or a derivative thereof. In some embodiments, the chemical spacer 120 may include a structure according to Formula II: -NH-C(O)-R 2 (II), In the formula, R 2 each of which may be optionally substituted with one or more substituents; 1 ~C 6 Alkyl or C 2 ~C 6 In some embodiments, R is alkenyl. 2 Non-limiting examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, ethenyl, propenyl, and butenyl.

[0059] In some embodiments, the chemical spacer 120 can include acrylamide, propionamide, isobutyramide, pivalamide, or any combination thereof.

[0060] In some embodiments, the weight ratio of graphene oxide sheets 110 to chemical spacers 120 in the graphene oxide film 100 can be less than about 1,000, less than about 500, less than about 400, less than about 300, less than about 200, less than about 100, less than about 50, less than about 25, less than about 15, less than about 10, or less than about 5 (including all values ​​and ranges therebetween). In some embodiments, the weight ratio of graphene oxide sheets 110 to chemical spacers 120 in the graphene oxide film 100 can be at least about 5, at least about 10, at least about 15, at least about 20, at least about 25, at least about 30, at least about 35, at least about 40, at least about 45, or at least about 50 (including all values ​​and ranges therebetween).

[0061] Combinations of the above-referenced ranges for weight ratios are also possible (eg, at least about 5 and less than about 1000, or at least about 10 and less than about 200).

[0062] In some embodiments, the atomic percent (at%) content of nitrogen present on the surface of the graphene oxide film 100 as measured by X-ray photoelectron spectroscopy can be less than about 5.0 at%, less than about 4.5 at%, less than about 4.0 at%, less than about 3.5 at%, less than about 3.2 at%, less than about 3.0 at%, less than about 2.8 at%, less than about 2.6 at%, less than about 2.4 at%, or less than about 2.0 at%, including all values ​​and ranges therebetween. In some embodiments, the atomic percent content of nitrogen present on the surface of the graphene oxide film 100 as measured by X-ray photoelectron spectroscopy can be at least about 0.6 at%, at least about 1.1 at%, at least about 1.2 at%, at least about 1.3 at%, at least about 1.4 at%, at least about 1.5 at%, at least about 1.6 at%, at least about 1.8 at%, or at least about 2.0 at%, including all values ​​and ranges therebetween. (including

[0063] Combinations of the above-referenced ranges for the atomic % nitrogen content are also possible (eg, at least about 0.6 atomic % and less than about 5.0 atomic %, or at least about 1.1 atomic % and less than about 3.2 atomic %).

[0064] In some embodiments, the atomic % content of carbon present on the surface of the graphene oxide film 100 as measured by X-ray photoelectron spectroscopy may be less than about 80%, less than about 78%, or less than about 75% (including all values ​​and ranges therebetween). In some embodiments, the atomic % content of carbon present on the surface of the graphene oxide film 100 as measured by X-ray photoelectron spectroscopy may be at least about 50%, at least about 55%, or at least about 60% (including all values ​​and ranges therebetween).

[0065] Combinations of the above-mentioned ranges for the atomic % carbon content are also possible (e.g., at least about 50% and less than about 80%, or at least about 60% and less than about 75%). In contrast, existing graphene oxide films that have been intentionally or unintentionally reduced often have an atomic % carbon content of greater than 80% or even greater than 95%.

[0066] In some embodiments, the graphene oxide film 100 may have a thickness of about 25 nm or more, about 50 nm or more, about 0.1 microns or more, about 0.15 microns or more, about 0.2 microns or more, about 0.3 microns or more, about 0.4 microns or more, about 0.5 microns or more, about 0.75 microns or more, about 1 micron or more, or about 2 microns or more. In some embodiments, the thickness of the graphene oxide film 100 may be about 5 microns or less, about 1 micron or less, about 0.75 microns or less, or about 0.5 microns or less.

[0067] Combinations of the above-referenced ranges for the thickness of the graphene oxide film 100 are also possible (eg, greater than or equal to about 25 nm and less than or equal to about 5 microns, greater than or equal to about 0.15 microns and less than or equal to about 0.5 microns).

[0068] In some embodiments, the graphene oxide film 100 may have a thickness of about 25 nm, about 50 nm, about 0.1 micron, about 0.15 micron, about 0.2 micron, about 0.25 micron, about 0.3 micron, about 0.35 micron, about 0.4 micron, about 0.45 micron, about 0.5 micron, about 0.55 micron, about 0.6 micron, about 0.65 micron, about 0.7 micron, about 0.75 micron, about 0.8 micron, about 0.85 micron, about 0.9 micron, about 0.95 micron, about 1.0 micron, about 1.5 micron, or about 2 microns.

[0069] In some embodiments, the graphene oxide sheet 110 can include flakes. The flakes can have an aspect ratio (in the plane of the graphene oxide sheet 110). In some embodiments, the aspect ratio can be less than about 250,000:1, less than about 100,000:1, less than about 50,000:1, less than about 25,000:1, less than about 10,000:1, less than about 5,000:1, less than about 1,000:1, at least about 100:1, at least about 200:1, at least about 300:1, at least about 400:1, or at least about 500:1 (including all values ​​and ranges therebetween).

[0070] In some embodiments, the graphene oxide film 100 may include at least about 100 layers, at least about 125 layers, at least about 150 layers, at least about 200 layers, at least about 225 layers, or at least about 250 layers of graphene oxide sheets (including all values ​​and ranges therebetween). In some embodiments, the graphene oxide film 100 may include up to about 600 layers, up to about 550 layers, up to about 500 layers, up to about 450 layers, up to about 400 layers, up to about 35 The graphene oxide may comprise 0 or less layers, or up to about 300 or less layers.

[0071] Combinations of the above-referenced ranges for the number of layers in the graphene oxide film 100 are also possible (e.g., at least about 100 and not more than about 600, or at least about 300 and not more than about 600, including all values ​​and ranges therebetween).

[0072] In some embodiments, the graphene oxide film 100 may include about 100 to about 600 graphene oxide sheets 110, such as 200 to 500 layers, 200 to 400 layers, 200 to 300 layers, 200 to 250 layers, 300 to 600 layers, 300 to 500 layers, or 300 to 400 layers.

[0073] In some embodiments, the space size between the graphene oxide sheets 110 is the d-spacing, which can be measured by X-ray diffraction, such as grazing incidence X-ray diffraction (GIXRD). In some embodiments, the d-spacing of the dry graphene oxide sheets 110 can be less than about 20 Å, less than about 15 Å, or less than about 10 Å (including all values ​​and ranges therebetween). In some embodiments, the d-spacing of the dry graphene oxide sheets 110 can be in the range of about 5 Å to about 20 Å, about 5 Å to about 15 Å, about 8 Å to about 20 Å, about 8 Å to about 15 Å (including all values ​​and ranges therebetween). In some embodiments, the d-spacing of the dry graphene oxide sheets 110 can be about 17 Å, about 16 Å, about 15 Å, about 14 Å, about 13 Å, about 12 Å, about 11 Å, about 10 Å, about 9 Å, about 8 Å, or about 7 Å. The length of the chemical spacer 120 is an important factor in controlling the d-spacing.

[0074] In some embodiments, the graphene oxide film 100 may have an average pore size of about 0.5 nm or more, about 1 nm or more, about 2 nm or more, about 3 nm or more, about 4 nm or more, or about 5 nm or more. In some embodiments, the graphene oxide film 100 may have an average pore size of about 6 nm or less, about 5 nm or less, about 4 nm or less, about 3 nm or less, or about 2 nm or less (including all values ​​and ranges therebetween).

[0075] Combinations of the above-mentioned ranges for average pore size are also possible (e.g., about 0.5 nm or more and about 6 nm or less, about 1 nm or more and about 6 nm or less). In some embodiments, the graphene oxide film 100 can have an average pore size of about 0.5 nm, about 0.8 nm, about 1 nm, about 2 nm, about 3 nm, about 4 nm, about 5 nm, or about 6 nm.

[0076] It has been discovered that the roughness of the support substrate can affect the flux of the graphene oxide film. Specifically, a smooth support substrate can improve the flux and / or rejection of the graphene oxide film compared to a rough support substrate. Thus, in some embodiments, the support substrate of the graphene oxide film 100 can have a root mean square surface roughness of less than about 3 μm, less than about 2.5 μm, less than about 2 μm, less than about 1.5 μm, or less than about 1 μm. In some embodiments, the support substrate of the graphene oxide film 100 can have a root mean square surface roughness of at least about 1 μm, at least about 1.2 μm, at least about 1.4 μm, at least about 1.5 μm (including all values ​​and ranges therebetween). In some embodiments, the surface roughness is measured by a Dektak 6M Contact Profilometer.

[0077] Combinations of the above-mentioned ranges for the root mean square surface roughness are also possible (e.g., at least about 1 μm and less than 2.5 μm, or at least 1.4 μm and less than about 3 μm). In some embodiments, the support substrate has a root mean square surface roughness of about 3 μm, about 2.5 μm, about 2 μm, about 1.5 μm, or about 1 μm.

[0078] In some embodiments, the color of the graphene oxide film 100 can be used to detect high temperatures and / or can assess the stability of the film under basic pH levels. The color of the graphene oxide film 100 can be characterized by recording an image of the graphene oxide film 100 and calculating the grayscale mode value using image processing software. The range of grayscale mode values ​​that the image can assume is 0-255, with values ​​closer to zero corresponding to a darker image and values ​​closer to 255 corresponding to a lighter image.

[0079] In some embodiments, the graphene oxide film 100 may exhibit a grayscale mode value of less than about 180, less than about 160, less than about 140, less than about 120, less than about 100, less than about 80, less than about 60, or less than about 40 (including all values ​​and ranges therebetween), and images of the graphene oxide film 100 are collected in a light box having dimensions of 9.4×9.1×8.7 inches and having two rows of 20 white LEDs on the top leading and trailing edges of the light box. In some embodiments, the graphene oxide film 100 may exhibit a grayscale mode value of at least about 20, at least about 25, at least about 30, at least about 45, at least about 60, at least about 75 (including all values ​​and ranges therebetween), and images of the graphene oxide film 100 are collected in a light box having dimensions of 9.4×9.1×8.7 inches and having two rows of 20 white LEDs on the top leading and trailing edges of the light box.

[0080] Combinations of the above-referenced ranges for the grayscale mode value are also possible (eg, at least about 20 and less than about 180, or at least about 90 and less than about 120).

[0081] Other methods of quantifying the color of the graphene oxide film 100 may also be used, for example, the shape of the distribution, the center of fit, and / or the standard deviation may be used.

[0082] The illumination level for obtaining the image of the graphene oxide film 100 may affect the grayscale mode value. For comparison purposes, two or more images of the same film or different films at different times should be obtained using the same or substantially the same illumination levels.

[0083] Flux may have units of gallons per square foot per day per psi (GFD / psi). In some embodiments, the graphene oxide membrane 100 has a flow rate of at least about 2.5×10 measured with a 1 wt % lactose solution at room temperature. -4 GFD / psi, at least about 5.0×10 -4 GFD / psi, at least about 7.5×10-4 GFD / psi, at least about 1.0×10 -3 GFD / psi, at least about 1.25 x 10 -3 GFD / psi, at least about 1.5×10 -3 GFD / psi, at least about 1.75 x 10 -3 GFD / psi, at least about 2.0×10 -3 GFD / psi, at least about 2.25 x 10 -3 GFD / psi, at least about 2.5×10 -3 GFD / psi, at least about 5.0×10 -3 GFD / psi, at least about 10.0 x 10 -3 GFD / psi, at least about 15.0 x 10 -3 GFD / psi, or at least about 20.0 x 10 -3 The fluid may have a flux of GFD / psi (including all values ​​and ranges therebetween).

[0084] In some embodiments, the graphene oxide film 100 has a viscosity of about 40.0×10 as measured in a 1 wt % lactose solution at room temperature. -3 GFD / psi or less, approximately 35.0×10 -3 GFD / psi or less, approximately 30.0×10 -3 GFD / psi or less, approximately 20.0×10 -3 GFD / psi or less, approximately 15.0×10 -3 GFD / psi or less, approximately 10.0×10 -3 The flux may be less than or equal to GFD / psi (including all values ​​and ranges therebetween).

[0085] Combinations of the above-referenced ranges for flux are also possible (e.g., at least about 2.5×10 -4 GFD / psi and approximately 40.0 x 10 -3 GFD / psi or less, or at least about 5.0 x 10 -3 GFD / psi and approximately 30.0 x 10 -3 GFD / psi or less).

[0086] In some embodiments, the flux is between 50 psi and 1000 psi, e.g., about 50 psi, about 75 psi, about 100 psi, about 125 psi, about 150 psi, about 175 psi, about 200 psi, about 225 psi, about 225 psi, 250 psi, about 275 psi, about 300 psi, about 325 psi, about 350 psi, about 375 psi, about 400 psi, about 425 psi, about 450 psi, about 475 psi, si, about 500 psi, about 525 psi, about 550 psi, about 575 psi, about 600 psi, about 625 psi, about 650 psi, about 675 psi, about 700 psi, about 725 psi, about 750 psi, about 775 psi, about 800 psi, about 825 psi, about 850 psi, about 875 psi, about 900 psi, about 925 psi, about 950 psi, about 975 psi, or about 1000 psi.

[0087] In some embodiments, the graphene oxide film 100 has a viscosity of about 2.5×10 as measured in a 1 wt % lactose solution at room temperature. -4 ~Approx. 3.75×10 -2 GFD / psi, approx. 2.5×10 -4 ~Approx. 2.5×10 -2 GFD / psi, approx. 2.5×10 -3 ~Approx. 2.5×10 -2 GFD / psi, or approximately 1.25 x 10 -2 ~Approx. 2.5×10 -2 The flux may be GFD / psi.

[0088] The temperature and / or pH durability of the graphene oxide film 100 can be evaluated by contacting the graphene oxide film 100 with a test solution having an elevated temperature and / or a non-neutral pH and comparing the solute rejection before and after contact.

[0089] In some embodiments, the graphene oxide membrane 100 may have a first solute rejection with a first solution having the solute at room temperature before being exposed to a test solution having an elevated temperature and / or a non-neutral pH. In some embodiments, the solute may include lactose, lignin, sodium sulfate, sodium carbonate, sodium hydrosulfide, sodium thiosulfate, sodium hydroxide, hydrochloric acid, nitric acid, phosphoric acid, sodium chloride, potassium chloride, and / or magnesium sulfate. The solute is dissolved in a solvent. In some embodiments, the solvent may include water, ethanol, methanol, acetone, or any other suitable solvent. In some embodiments, the graphene oxide membrane 100 may have a second solute rejection with a second solution having the solute at room temperature after being exposed to the test solution for a contact period.

[0090] In some embodiments, the first solution and / or the second solution comprises about 0.1% by weight of solute, about 0.2% by weight of solute, about 0.3% by weight of solute, about 0.4% by weight of solute, about 0.5% by weight of solute, about 0.6% by weight of solute, about 0.7% by weight of solute, about 0.8% by weight of solute, about 0.9% by weight of solute, about 1% by weight of solute, about 1.5% by weight of solute, about 2% by weight of solute, about 2.5% by weight of solute, about 3% by weight of solute, about 4% by weight of solute, about 5% by weight of solute, about 6% by weight of solute, about 7% by weight of solute, about 8% by weight of solute, about 9% by weight of solute, about 10% by weight of solute, about 11% by weight of solute, about 12% by weight of solute, about 13% by weight of solute, about 14% by weight of solute, about 15% by weight of solute, about 16% by weight of solute, about 17% by weight of solute, about 18% by weight of solute, about 19% by weight of solute, about 20% by weight of solute, about 21% by weight of solute, about 22% by weight of solute, about 23% by weight of solute, about 24% by weight of solute, about 25% by weight of solute, about 26% by weight of solute, about 27% by weight of solute, about 28% by weight of solute, about 29% by weight of solute, about 30% by weight of solute, about 31% by weight of solute, about 32% by weight of solute, about 33% by weight of solute, about 34% by weight of solute, % solute, about 3.5% solute, about 4% solute, about 4.5% solute, about 5% solute, about 5.5% solute, about 6% solute, about 6.5% solute, about 7% solute, about 7.5% solute, about 8% solute, about 8.5% solute, about 9% solute, about 9.5% solute, or about 10% solute (including all values ​​and ranges therebetween).

[0091] In some embodiments, the test solution may have an elevated temperature, a non-neutral pH, or any combination thereof. In some embodiments, the elevated temperature may be greater than about 50° C., greater than about 55° C., greater than about 60° C., greater than about 65° C., greater than about 70° C., greater than about 75° C., greater than about 80° C., greater than about 85° C., greater than about 90° C., or greater than about 95° C. (including all values ​​and ranges therebetween). In some embodiments, the elevated temperature may be about 100° C. or less, about 95° C. or less, about 90° C. or less, about 85° C. or less, or about 80° C. or less (including all values ​​and ranges therebetween).

[0092] Combinations of the above-referenced ranges of temperature are also possible (e.g., greater than about 50° C. and about 100°C or less, about 60°C or more and about 100°C or less, or about 80°C or more and about 120°C or less).

[0093] In some embodiments, the non-neutral pH can be at least about 8, at least about 8.5, at least about 9, at least about 9.5, at least about 10, at least about 10.5, at least about 11, at least about 11.5, at least about 12, at least about 12.5, at least about 13, at least about 13.5, or at least about 14. In some embodiments, the non-neutral pH can be less than about 6, less than about 5.5, less than about 5, less than about 4.5, less than about 4, less than about 3.5, less than about 3, less than about 2.5, less than about 2, less than about 1.5, less than about 1, or less than about 0.5 (including all values ​​and ranges therebetween). In some embodiments, the non-neutral pH can be about 0, about 0.5, about 1, about 1.5, about 2, about 2.5, about 3, about 3.5, about 4, about 4.5, about 5, about 5.5, about 6, about 8, about 8.5, about 9, about 9.5, about 10, about 10.5, about 11, about 11.5, about 12, about 12.5, about 13, about 13.5, or about 14 (including all values ​​and ranges therebetween).

[0094] In some embodiments, the first solute rejection can be at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, at least about 99.5%, or about 100% (including all values ​​and ranges therebetween).

[0095] In some embodiments, the second solute rejection can be at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, at least about 99.5%, or about 100% (including all values ​​and ranges therebetween).

[0096] In some embodiments, the first lactose rejection using a 1 wt% lactose solution can be at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, at least about 99.5%, or about 100% (including all values ​​and ranges therebetween).

[0097] In some embodiments, the second lactose rejection using a 1 wt% lactose solution can be at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, at least about 99.5%, or about 100% (including all values ​​and ranges therebetween).

[0098] In some embodiments, when the membrane is temperature and / or pH durable, the second solute rejection can be substantially the same as the first solute rejection. In some embodiments, when the membrane is temperature and / or pH durable, the second solute rejection can be greater than the first solute rejection. For example, the second solute rejection can be at least about 5%, at least about 10%, at least about 15%, or at least about 20% greater than the first solute rejection.

[0099] In some embodiments, the test solution may be a buffer. In some embodiments, the test solution may include a phosphate buffer. In some embodiments, the test solution may include a Na 2 HPO 4 In some embodiments, the test solution may have a concentration of about 0.1 M, about 0.2 M, about 0.3 M, about 0.4 M, about 0.5 M, about 0.6 M, about 0.7 M, about 0.8 M, about 0.9 M, about 1 M, about 2 M, about 3 M, about 4 M, about 5 M, or about 6 M (including all values ​​and ranges therebetween).

[0100] In some embodiments, the contact period can be greater than about 10 minutes, greater than about 20 minutes, greater than about 30 minutes, greater than about 40 minutes, greater than about 50 minutes, greater than about 1 hour, greater than about 1.5 hours, greater than about 2 hours, greater than about 2.5 hours, greater than about 3 hours, greater than about 3.5 hours, greater than about 4 hours, greater than about 4.5 hours, greater than about 5 hours, greater than about 5.5 hours, greater than about 6 hours, greater than about 6.5 hours, greater than about 7 hours, greater than about 7.5 hours, greater than about 8 hours, greater than about 8.5 hours, greater than about 9 hours, greater than about 9.5 hours, or greater than about 10 hours (including all values ​​and ranges therebetween).

[0101] In some embodiments, the contact period can be less than about 10 hours, less than about 9.5 hours, less than about 9 hours, less than about 8.5 hours, less than about 8 hours, less than about 7.5 hours, less than about 7 hours, less than about 6.5 hours, less than about 6 hours, less than about 5.5 hours, less than about 5 hours, less than about 4.5 hours, less than about 4 hours, less than about 3.5 hours, less than about 3 hours, less than about 2.5 hours, less than about 2 hours, less than about 1.5 hours, less than about 1 hour, less than about 50 minutes, less than about 40 minutes, less than about 30 minutes, or less than about 20 minutes (including all values ​​and ranges therebetween).

[0102] In some embodiments, the contact period can be from about 1 hour to about 10 hours, from about 1 hour to about 9 hours, from about 1 hour to about 8 hours, from about 1 hour to about 7 hours, from about 1 hour to about 6 hours, from about 1 hour to about 5 hours, from about 1 hour to about 4 hours, from about 1 hour to about 3 hours, from about 1 hour to about 2 hours, from about 2 hours to about 10 hours, from about 2 hours to about 9 hours, from about 2 hours to about 8 hours, from about 2 hours to about 7 hours, from about 2 hours to about 6 hours, from about 2 hours to about 5 hours, from about 2 hours to about 4 hours, from about 2 hours to about 3 hours, from about 3 hours to about 10 hours, from about 3 hours to about 9 hours, from about 3 hours to about 8 hours, from about 3 hours to about 7 hours, from about 3 hours to about 6 hours, from about 3 hours to about 5 hours, or from about 3 hours to about 4 hours.

[0103] The temperature and / or pH durability of the graphene oxide film 100 can also be evaluated by contacting the graphene oxide film 100 with a test solution having an elevated temperature and / or a non-neutral pH for a period of time and comparing the grayscale mode values ​​before and after contact. In some embodiments, if the film is temperature and / or pH durable, the grayscale mode value changes by about 30% or less, about 25% or less, about 20% or less, about 15% or less, about 10% or more after contact. In some embodiments, if the film is temperature and / or pH durable, the grayscale mode value changes by about 50 or less, about 40 or less, about 30 or less, or about 20 or less after contact. The contact period can be about several hours (e.g., about 2 hours, about 4 hours, about 6 hours, about 8 hours, about 10 hours, about 12 hours, about 14 hours, about 16 hours, about 18 hours, about 20 hours, or about 22 hours), about one day, or about two days.

[0104] The procedure for characterizing the blocking and permeability properties of the graphene oxide membrane is as follows: (1) cut a 47-50 mm disk from the graphene oxide membrane using a razor blade or laser cutter, (2) place the disk, graphene oxide side up, on a porous stainless steel frit, which is then attached to a Sterlitech HP4750 filtration cell, (3) add 60-100 mL of 1 wt% lactose solution, (4) place the construct on a stir plate at approximately 750 rpm, and (5) close the feed chamber and allow it to dry. Pressurize to 50-100 psi. During this procedure, at least 15 mL of permeate is collected from three samples to ensure that the performance measurements are stable.

[0105] In some embodiments, the molecular weight cutoff for graphene oxide films is about 100 Da. In some embodiments, the molecular weight cutoff for graphene oxide films is about 150 Da. In some embodiments, the molecular weight cutoff for graphene oxide films is about 200 Da. In some embodiments, the molecular weight cutoff for graphene oxide films is about 250 Da. In some embodiments, the molecular weight cutoff for graphene oxide films is about 300 Da. In some embodiments, the molecular weight cutoff for graphene oxide films is about 350 Da.

[0106] In one aspect, the flux of the graphene oxide film 100 can be increased by contacting the film 100 for a period of time with a pretreatment solution that is at least about 50° C. In some embodiments, the pretreatment solution flows through the film 100 during the contacting step.

[0107] In some embodiments, the membrane 100 is contacted with a pretreatment solution at or below about 100° C., at or below about 90° C., at or below about 80° C., at or below about 70° C., or at or below about 60° C. (including all values ​​and ranges therebetween). In some embodiments, the membrane 100 is contacted with a pretreatment solution that is at least about 50° C., at least about 55° C., at least about 60° C., at least about 65° C., or at least about 70° C. (including all values ​​and ranges therebetween).

[0108] Combinations of the above-referenced ranges for the temperature of the test solution are also possible (eg, a temperature of at least about 50° C. and not more than about 100° C., or at least about 60° C. and not more than about 90° C.).

[0109] In another aspect, the flux of the graphene oxide film 100 can be increased by contacting the film 100 with a basic pretreatment solution at room temperature or above room temperature. In some embodiments, the pretreatment solution flows through the film 100 during the contacting step.

[0110] In some embodiments, the basic pretreatment solution has a pH of about 14, less than about 13.5, less than about 13, less than about 12.5, less than about 12, less than about 11.5, less than about 11, less than about 10.5, less than about 10, less than about 9.5, less than about 9 (including all values ​​and ranges therebetween). In some embodiments, the basic pretreatment solution has a pH of at least about 8.0, at least about 8.5, at least about 9.0, at least about 9.5, at least about 10, or at least about 10.5 (including all values ​​and ranges therebetween).

[0111] Combinations of the above-referenced ranges for the pH of the basic pretreatment solution are also possible (eg, at least about 8.0 and less than about 13, or at least about 9.0 and less than about 12).

[0112] In some embodiments, the period of time that the membrane is in contact with the pretreatment solution to increase the flux may be less than about 400 hours, less than about 300 hours, less than about 200 hours, less than about 100 hours, less than about 40 hours, less than about 20 hours, less than about 10 hours, less than about 8 hours, less than about 6 hours, less than about 4 hours, or less than about 2 hours (including all values ​​and ranges therebetween). In some embodiments, the period of time that the membrane is in contact with the pretreatment solution to increase the flux may be at least about 0.5 hours, at least about 1 hour, at least about 1.5 hours, at least about 2 hours, at least about 3 hours, at least about 4 hours, or at least about 8 hours (including all values ​​and ranges therebetween). In general, when high temperatures are used, less time is required to increase the flux than when room temperature or low temperatures are used.

[0113] Combinations of the above-referenced ranges for the certain periods of time are also possible (eg, at least about 0.5 hours and less than about 400 hours, at least about 2 hours and less than about 100 hours, or about 2 hours and less than about 10 hours).

[0114] In some embodiments, the increase in flux after the contacting step can be less than about 1,000%, less than about 900%, less than about 800%, less than about 700%, less than about 600%, less than about 500%, less than about 400%, less than about 300%, less than about 200%, or less than about 100%, including all values ​​and ranges therebetween. In some embodiments, the increase in flux after the contacting step can be at least about 40%, at least about 50%, at least about 60%, at least about 90%, at least about 150%, or at least about 200%, including all values ​​and ranges therebetween.

[0115] Combinations of the above-referenced ranges of flux increase are also possible (eg, at least about 40% and less than about 1,000%, or at least about 60% and less than about 600%).

[0116] filtration device In another aspect, the present disclosure provides a filtration device that includes a support substrate, a graphene oxide membrane 100 of the present disclosure, and optionally a housing. The graphene oxide membrane 100 can be disposed on the support substrate. The housing can encapsulate the support substrate and the graphene oxide membrane 100.

[0117] The support substrate may include non-woven fibers or polymers. In some embodiments, the support substrate may include a material selected from polypropylene (PP), polystyrene, polyethylene, polyethylene oxide, polyethersulfone (PES), polytetrafluoroethylene (PTFE), polyvinylidene fluoride, polymethylmethacrylate, polydimethylsiloxane, polyester, polyolefin, cellulose, cellulose acetate, cellulose nitrate, polyacrylonitrile, fiberglass, quartz, alumina, silver, polycarbonate, nylon, Kevlar or other aramids, or polyetheretherketone.

[0118] In some embodiments, the support substrate is a microporous substrate. The support substrate may have an average pore size of 0.1 μm to 10 μm, for example, 0.1 μm to 8 μm, 0.1 μm to 5 μm, 0.2 μm to 5 μm, 0.2 μm to 2 μm, or 0.2 μm to 1 μm. In some embodiments, the support substrate may have an average pore size of less than 1 μm, for example, about 0.2 μm, about 0.3 μm, about 0.4 μm, about 0.45 μm, about 0.5 μm, about 0.55 μm, about 0.6 μm, about 0.65 μm, about 0.7 μm, or about 0.75 μm.

[0119] In some embodiments, the graphene oxide film 100 and supporting substrate may have a combined thickness of about 100 microns, about 150 microns, about 200 microns, about 250 microns, about 300 microns, about 350 microns, about 400 microns, about 450 microns, about 500 microns (including all values ​​and ranges therebetween).

[0120] In some embodiments, the support substrate may include two or more layers. For example, the support substrate may include a first layer and a second layer, the first layer being disposed on the second layer, and the first layer and the second layer having different average pore sizes. In some embodiments, the graphene oxide membrane is disposed on the first layer, and the first layer has a smaller average pore size than the second layer.

[0121] In some embodiments, the support substrate may include a hollow polymer tube. -The tube is about 100cm long. 2 The surface area may be greater than or equal to 100 nm.

[0122] In some embodiments, the graphene oxide membrane 100 may include multiple flat polymer sheets combined to form a spiral filtration module. For example, in some embodiments, the spiral filtration module may include multiple flat polymer sheets stacked on top of each other, and the multiple stacked flat polymer sheets may be wound around a core tube. In some embodiments, prior to winding around the core tube, adjacent flat polymer sheets may be separated by sheets of feed channel spacers to form leaves, and each of the leaves may be separated by sheets of permeate spacers. When the flat polymer sheets, one or more feed channel spacers, and one or more permeate spacers are wound around the core tube, each of the permeate spacers may form a permeate channel.

[0123] Without wishing to be bound by theory, the graphene oxide films described herein can withstand high pressure operation, e.g., from about 500 psi to 1600 psi or more, because the chemical spacer holds the graphene oxide sheets together through strong hydrogen bonds, allowing the sheets to shift past each other under high pressure compression. In some embodiments, the support substrate can have a Young's modulus of about 3.0 GPa or less, about 2.5 GPa or less, about 2.0 GPa or less, about 1.8 GPa or less, about 1.6 GPa or less, about 1.4 GPa or less, or about 1.2 GPa or less (including all values ​​and ranges therebetween). In some embodiments, the support substrate can have a Young's modulus of at least about 0.5 GPa, at least about 0.6 GPA, at least about 0.7 GPa, at least about 0.8 GPa, at least about 0.9 GPa, at least about 1.0 GPa, at least about 1.1 GPa, at least about 1.3 GPa, at least about 1.5 GPa, or at least about 2.0 GPa (including all values ​​and ranges therebetween).

[0124] Combinations of the above-referenced ranges for the Young's modulus of the supporting substrate are also possible (eg, a Young's modulus of at least about 0.5 GPa and less than or equal to about 3.0 GPa, or a Young's modulus of at least about 1.5 GPa and less than or equal to about 3.0 GPa).

[0125] In some embodiments, the high pressure operation is about 900 psi, about 1000 psi, about 1100 psi, about 1200 psi, about 1300 psi, about 1400 psi, about 1500 psi, or about 1600 psi.

[0126] For high pressure durability, the support substrate may have a thickness of about 750 μm or less, about 700 μm or less, about 650 μm or less, about 550 μm or less, about 500 μm or less, about 450 μm or less, or about 400 μm or less (including all values ​​and ranges therebetween). In some embodiments, the support substrate may have a thickness of at least about 200 μm, at least about 220 μm, or at least about 240 μm (including all values ​​and ranges therebetween).

[0127] Combinations of the above-referenced ranges for the thickness of the supporting substrate for high pressure durability are also possible (eg, a thickness of at least about 200 μm and not more than about 750 μm, at least about 240 μm and not more than about 500).

[0128] In some embodiments, the supporting substrate suitable for high pressure resistance may include PES, PTFE, PP, PAN, polyolefins, nylon, or combinations thereof.

[0129] The support substrate can have one, two, three, or more layers. In some embodiments, the support substrate can include a first layer in contact with the membrane 100 and a second layer disposed on the first layer, the second layer being configured to provide additional mechanical support. The first layer may comprise the same material as the second layer. For example, the first layer may comprise PES and the second layer may comprise PES. The first layer may comprise a different material than the second layer.

[0130] In some embodiments, the supporting substrate can include a first layer in contact with the membrane 100, a second layer disposed on the first layer, and a third layer disposed on the second layer. For example, the first layer can include PTFE, the second layer can include PP, and the third layer can include PES.

[0131] In some embodiments, the supporting substrate can include a first layer in contact with the membrane 100, a second layer disposed on the first layer, a third layer disposed on the second layer, and a fourth layer disposed on the third layer. For example, the first layer can include PTFE, the second layer can include PP, the third layer can include PTFE, and the fourth layer can include PP.

[0132] To test whether the graphene oxide membrane on the support substrate can withstand high pressure operation, the graphene oxide membrane on the support substrate having a first lactose rejection of at least 50% using a first 1 wt% lactose solution at room temperature is subjected to a pressure of about 1000 psi for a certain period of time. If the graphene oxide membrane then has a second lactose rejection of at least 50% using a second 1 wt% lactose solution at room temperature, the membrane is considered to be able to withstand high pressure operation. In some embodiments, the certain period of time is about 1 hour to 24 hours, for example, about 1 hour, about 2 hours, about 3 hours, about 4 hours, about 5 hours, about 6 hours, about 7 hours, about 8 hours, about 9 hours, about 10 hours, about 11 hours, about 12 hours, about 13 hours, about 14 hours, about 15 hours, about 16 hours, about 17 hours, about 18 hours, about 19 hours, about 20 hours, about 21 hours, about 22 hours, about 23 hours, or about 24 hours. In some embodiments, for testing purposes, the support substrate is mounted on a standard tricot permeate carrier (eg, 0.012 inches thick, approximately 5 ounces per square yard, and 50 wales and 48 courses per inch).

[0133] Fabrication of graphene oxide membrane and filtration device Fabrication of the membrane 100 involves dispersing the graphene oxide sheets 110 in a solvent to produce a stable dispersion. In some embodiments, the solvent can be water. In some embodiments, the solvent can be organic. The dispersion can exhibit certain physical and chemical properties to produce a continuous and uniform coating that is substantially free of structural defects such as pinholes. For example, the hydrophilicity of the dispersion must be appropriately matched to the supporting substrate to ensure wetting of the supporting substrate surface. This can be tested by contact angle measurements.

[0134] The stability of a dispersion can be inferred from the pH of the dispersion. For example, a dispersion exhibiting an acidic pH value (e.g., pH≦5) may result in visible aggregates. Creating a coating with such a dispersion leads to reduced coverage, non-uniformity of the coating, and reduced film performance. In contrast, a dispersion with a basic pH is stable. Furthermore, the addition of a basic additive to the dispersion can increase the degree of zeta potential on the graphene oxide sheets 110, thereby resulting in greater Coulomb stabilization.

[0135] The stability of the dispersion is determined by the ratio of n to p * This can be indirectly observed by UV-Vis spectroscopy from the absorption band at about 300 nm due to the transition to . At longer wavelengths (>500 nm), the graphene oxide sheets 110 absorb very weakly, so that the signal in this region can be attributed to scattering rather than absorption due to the formation of aggregates. The ratio of the UV-Vis signal at 300 nm (due to absorption) and the UV-Vis signal observed at 600 nm (due to scattering of aggregates) can be used to characterize the dispersion in solution. In general, the higher this ratio, the better the graphene oxide sheets 110 are dispersed.

[0136] In some embodiments, the ratio of the UV-Vis signal at 300 nm and the UV-Vis signal observed at 600 nm can be less than about 4.4, less than about 4.2, less than about 4.0, less than about 3.8, less than about 3.6, less than about 3.4, less than about 3.2, or less than about 3.0 (including all values ​​and ranges therebetween). In some embodiments, the ratio of the UV-Vis signal at 300 nm and the UV-Vis signal observed at 600 nm can be at least about 3.0, at least about 3.1, at least about 3.2, at least about 3.3, or at least about 3.4 (including all values ​​and ranges therebetween).

[0137] Combinations of the above-referenced ranges for ratios are also possible (eg, a ratio of at least about 3.0 and less than about 4.4, at least about 3.2 and less than about 4.0).

[0138] In some embodiments, the dispersion may further include a viscosity modifier and / or a surfactant. In some embodiments, the viscosity modifier is hydroxypropyl methylcellulose (HPMC). For example, the dispersion may include about 0.01% by weight of the viscosity modifier. In some embodiments, the surfactant is sodium dodecyl sulfate (SDS). For example, the dispersion may include about 0.15% by weight of the surfactant.

[0139] In some embodiments, the viscosity of the dispersion may be about 100 cP or less at a shear rate of about 50 Hz, about 90 cP or less at a shear rate of about 50 Hz, about 80 cP or less at a shear rate of about 50 Hz, or about 70 cP or less at a shear rate of about 50 Hz. In some embodiments, the viscosity of the dispersion may be at least about 10 cP at a shear rate of about 50 Hz, at least about 20 cP at a shear rate of about 50 Hz, or at least about 30 cP at a shear rate of about 50 Hz.

[0140] Combinations of the above-referenced ranges for the viscosity of the dispersion are also possible (eg, a viscosity of at least about 10 cP and no more than about 100 cP at a shear rate of about 50 Hz, at least about 20 cP and no more than about 90 cP at a shear rate of about 50 Hz).

[0141] The order of addition of reagents can be important to produce a dispersion that can be successfully coated onto a support substrate. For example, dispersions that undergo carbodiimide coupling conditions prior to deposition should have their pH adjusted to above 8.0 prior to the addition of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS).

[0142] Prior to reaction with the chemical spacer precursor, the graphene oxide sheets can be functionalized with one or more desired chemical groups. For example, the graphene oxide sheets can be functionalized with amines. See Navaee, A. & Salimi, A, “Efficient amine functionalization of graphene oxide through the Bucherer reaction: an extraordinary metal-free electrocatalyst for the oxygen reduction reaction,” RSC Adv. 5, 59874-59880 (2015), the contents of which are incorporated by reference.

[0143] Graphene oxide sheets can also be functionalized with carboxyl groups. See Sydlik, SA & Swager, TM, “Functional Graphenic Materials Via Johns Hopkins University, 1999, the contents of each of which are incorporated by reference. See, e.g., Collins, W. R. et al., “Rearrangement of Graphite Oxide: A Route to Covalently Functionalized Graphenes,” Angew. Chem., Int. Ed. 50, 8848-8852 (2011).

[0144] In some embodiments, the graphene oxide sheets can be functionalized with hydroxyl groups. For example, the graphene oxide sheets can be reacted with epoxides such that the graphene oxide sheets are functionalized with hydroxyl groups. Examples of epoxides include, but are not limited to, 1,2-epoxypropane, styrene oxide, ethylene oxide, epichlorohydrin, 1,2-epoxybutane, bisphenol A diglycidyl ether, 1,3-butadiene diepoxide, and 1,2,7,8-diepoxyoctane.

[0145] When the graphene oxide sheets have the desired chemical groups, they can be placed in contact with a chemical spacer precursor to initiate a reaction between the graphene oxide sheets and the chemical spacer precursor. The reaction conditions can vary depending on the chemical spacer precursor used. Compared to existing processes, some embodiments of the process of the present disclosure can be carried out under ambient conditions (i.e., in the presence of oxygen and moisture).

[0146] In some embodiments, the reaction between the graphene oxide sheets 110 and the chemical spacer precursor is carried out in solution to produce the graphene oxide film 100, which is then cast onto a support substrate. Figures 2A-2F present some examples of reactions involving graphene oxide sheets and chemical spacers. In Figures 2A and 2B, the graphene oxide sheets are reacted with propionamide, whereby each of the epoxide and carboxylic acid groups on the graphene oxide sheets are functionalized with the propionamide. In Figures 2C and 2D, the graphene oxide sheets are reacted with isobutyramide, whereby at least a portion of the epoxide and carboxylic acid groups on the graphene oxide sheets are functionalized with the isobutyramide. In Figures 2E and 2F, the graphene oxide sheets are reacted with pivalamide, whereby at least a portion of the epoxide and carboxylic acid groups on the graphene oxide sheets are functionalized with the pivalamide. Each of these reactions can occur in a solution of NHS, EDC, and triethylamine (TEA).

[0147] In some embodiments, triethylamine (TEA), 1,4-diazabicyclo[2.2.2]octane (DABCO), potassium hydroxide (KOH), sodium hydroxide (NaOH), cesium hydroxide (CsOH), lithium hydroxide (LiOH), or other bases can often be used to deprotonate the relevant alcohol groups and facilitate the reaction. In some embodiments, the base is TEA. In some embodiments, the base is CsOH. In some embodiments, the pH of the reaction is in the range of about 9 to 13, e.g., about 9, about 9.5, about 10, about 10.5, about 11, about 11.5, about 12, about 12.5, or about 13.

[0148] In some embodiments, the reaction temperature is about 50°C to 70°C, for example, about 50°C, about 55°C, about 60°C, about 65°C, or about 70°C.

[0149] In some embodiments, the filtration device can be fabricated by depositing a graphene oxide film onto a suitable supporting substrate.

[0150] In some embodiments, the filtration device comprises a plurality of graphene oxide sheets supported on a suitable support substrate. The graphene oxide film can be fabricated by depositing the graphene oxide film on a silicon substrate and then forming the graphene oxide film in situ.

[0151] In some embodiments, the filtration device can be fabricated according to the following steps: (a) depositing a plurality of graphene oxide sheets onto a suitable support substrate, (b) immersing the graphene oxide sheets and support substrate in a solution containing a chemical spacer precursor, (c) reacting the graphene oxide with the chemical spacer precursor under suitable conditions, and (d) washing the graphene oxide sheets and support substrate. The graphene oxide sheets can be functionalized with one or more chemical groups prior to deposition. If the substrate comprises PES, DMF is not used to wash the substrate.

[0152] In some embodiments, the filtration device can be fabricated according to the following steps: (a) mixing a plurality of graphene oxide sheets and a chemical spacer precursor in a solvent, (b) depositing the graphene oxide sheets and the chemical spacer precursor onto a suitable support substrate, (c) soaking or coating the support substrate with an activating agent, and (d) washing the graphene oxide sheets and the support substrate. The graphene oxide sheets can be functionalized with one or more chemical groups prior to deposition.

[0153] Purpose The graphene oxide membranes or filtration devices disclosed herein can be used in a wide range of nanofiltration or microfiltration applications, including, but not limited to, molecular concentration (e.g., whey, lactose), kraft pulping (e.g., wood pulp), sulfite pulping, desalination (e.g., lactose, dyes, chemicals, pharmaceuticals), fractionation (e.g., sugars), extraction (e.g., dietary supplements, vegetable oils), recovery (e.g., catalysts, solvents), and purification (e.g., pharmaceuticals, chemicals, fuels). For example, a fluid containing multiple species (e.g., multiple retentate species) can be placed in contact with a first side of the graphene oxide membrane. The graphene oxide membrane can have interlayer and / or intralayer spacings sized to prevent at least a portion of the species from traversing the membrane through the interlayer and / or intralayer spacings, i.e., flowing from the first side of the graphene oxide membrane to a second, opposite side of the graphene oxide membrane. In some embodiments, the fluid can include one or more types of species (e.g., retentate or permeate species). In some embodiments, the graphene oxide membrane may have interlayer and / or intralayer spacing sized to allow at least a portion (e.g., substantially all) of the permeate species to traverse the graphene oxide membrane, while preventing at least a portion of the retentate species from traversing the graphene oxide membrane.

[0154] The graphene oxide membranes or filtration devices disclosed herein can be used in reverse osmosis to remove ions, molecules, and larger particles from fluids, such as drinking water.

[0155] In some embodiments, the graphene oxide membranes or filtration devices disclosed herein may be used in methods for filtering raw milk, cheese whey, whey protein concentrate, mixtures containing lactose, and whey protein isolates, which may include passing raw milk through a graphene oxide membrane.

[0156] The graphene oxide membranes or filtration devices disclosed herein can also be used to remove lignin from black liquor. Weak black liquor from pulp digestion is generally produced at 80°C-90°C. Cooling the weak black liquor before filtration would be very costly and energy intensive. Without the need for cooling, the weak black liquor can be passed through the graphene oxide membranes described herein at high temperatures, e.g., 80°C-90°C or 75°C-85°C. In some embodiments, the black liquor can be passed through the filtration devices described herein, where the black liquor is Lignin, sodium sulfate, sodium carbonate, sodium hydrosulfide, sodium thiosulfate, and / or sodium hydroxide.

[0157] The performance of the membrane for black liquor filtration can be evaluated by the rejection rate relative to the total solids content. In some embodiments, the rejection rate is about 75% to about 95% relative to the total solids content, for example, about 75% to about 90%, about 75% to about 85%, or about 80% to about 95% relative to the total solids content.

[0158] In some embodiments, the graphene oxide film can reject at least a portion of the lignin, ie, the graphene oxide film can reject at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or at least about 99.5% of the lignin.

[0159] In some embodiments, the graphene oxide film can reject at least a portion of the sodium sulfate, ie, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or at least about 99.5% of the sodium sulfate.

[0160] In some embodiments, the graphene oxide film can reject at least a portion of the sodium carbonate, ie, the graphene oxide film can reject at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or at least about 99.5% of the sodium carbonate.

[0161] In some embodiments, the graphene oxide film can reject at least a portion of the sodium hydrosulfide, ie, the graphene oxide film can reject at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or at least about 99.5% of the sodium hydrosulfide.

[0162] In some embodiments, the graphene oxide film can reject at least a portion of the sodium thiosulfate, ie, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or at least about 99.5% of the sodium thiosulfate.

[0163] In some embodiments, the graphene oxide film can reject at least a portion of the sodium hydroxide, ie, the graphene oxide film can reject at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or at least about 99.5% of the sodium hydroxide.

[0164] In some embodiments, the graphene oxide film is designed using simulations. Figure 3 is a modeling diagram that models a membrane system of any size using a simple diagram of permeability and rejection from dead ends or cross flows. Based on the results of these simulations, graphene oxide membranes with high rejection can process weak black liquor at high operating pressures. In some embodiments, even with relatively low (<80%) rejection of a particular salt, the desired rejection percentage can be achieved by passing the permeate through a second, smaller system. In some embodiments, the designed membrane has specific rejection targets for hydroxides, monovalent salts, divalent salts, weak black liquor (WBL), and / or different organic components of the WBL. In some embodiments, the composition of the permeate can be estimated based on the membrane system selected.

[0165] In some embodiments, models of membrane systems of any size can be developed based on permeability data and rejection from dead ends or cross flows. In some embodiments, every constituent species can be tracked. Counterions (e.g., sodium) can be given the same rejection as their paired ions (e.g., sodium paired with lignin, sodium paired with Cl, sodium paired with sulfate). In some embodiments, total or species fluxes can be calculated based on the formulas presented in Figure 3.

[0166] In some embodiments, the system can be designed with only a first pass ("single pass"). In some embodiments, the feed can be split into a set of five spirals in series. In some embodiments, the system can be designed as a multi-pass (e.g., two-pass). In some embodiments, the permeate from the first system can be passed as feed to a second simulation. In some embodiments, the retentate from both systems can be collected and combined. In some embodiments, the system design is intended to reduce operating pressure and / or provide a cleaner permeate.

[0167] In some embodiments, the model of the filtration system may include fixed and / or variable parameters. In some embodiments, the fixed parameters may include feed interval, permeability, temperature, viscosity, molar volume, density, large organic rejection, minimum driving pressure (feed pressure-feed osmotic pressure), relative amount of each WBL component (percent of total dissolved solids for each of the non-hydroxide solute components), molecular weight, and / or methanol level. In some embodiments, the temperature may be about 80° C. In some embodiments, the minimum driving pressure may be about 1 MPa. In some embodiments, the molecular weight of the lignin may be about 5,000 Da. In some embodiments, the molecular weight of the dissolved carbohydrates and hemicelluloses may be about 500. In some embodiments, the methanol level may be about 1 wt%.

[0168] In some embodiments, the variable parameters may include the number of modules in each pass, total dissolved solids (TDS), pressure, divalent rejection, difference between divalent and monovalent rejection, and / or hydroxide rejection. In some embodiments, the TDS may be about 9% to about 18% by weight. In some embodiments, the TDS may be about 9%, about 10%, about 11%, about 12%, about 13%, about 14%, about 15%, about 16%, about 17%, about 18% by weight (including all values ​​and ranges therebetween). In some embodiments, the TDS may be about 12.5% ​​to about 16.5% by weight. In some embodiments, the pressure may be about 4 MPa to about 10 MPa. In some embodiments, the organic rejection may be about 1. In some embodiments, the divalent rejection may be about 0.4 to about 1. In some embodiments, the monovalent rejection may be about 0.05 to about 0.2 less than the divalent rejection. In some embodiments, hydroxide rejection can be from about 0 to approximately equal to monovalent rejection.

[0169] The high temperature capabilities of these membranes enable their use in reverse osmosis, such as for thickening WBL in the kraft and sulfite pulping industries. This can be illustrated in Figures 4-9E. The concentration, production rate, and composition of WBL vary greatly from mill to mill.

[0170] Concentration of a liquid by a membrane process was modeled. A discretized fluid (Figure 3) is considered flowing between two parallel membrane sheets at high pressure. Depending on the membrane permeability and fluid pressure, a certain amount of fluid passes through the membrane sheets on both sides. The membrane rejection properties determine the composition of the permeate. The fluid then becomes the next discretized fluid element according to mass conservation. Once the fluid reaches the end of the membrane system, the solution is considered to be the concentrate. The sum of all discretized permeate elements is the total permeate. Hence, the recovery ratio or percentage of the feed that becomes the permeate is related to the strength of the concentrate and the rate of permeate production by the system. Various feed pressures, membrane rejection, and liquid strengths are illustrated.

[0171] Figure 4 shows how this permeate composition depends on the total strength (% solids) of the feed weak black liquor when the membrane rejects 100% of the dissolved organics and divalent anions. The membrane rejects 80-95% of the monovalent anions. The lower the permeate TDS, the cleaner and easier the permeate is to recycle. All membrane systems show low permeate solids, even over a wide range of feed dissolved solids.

[0172] Figures 5A-5D illustrate the effect of different membrane rejections on permeate quality. Divalent ion rejection varies from 70% to 100%. Within each figure, monovalent anion rejection is 5-20 percentage points lower than divalents. High rejection membrane designs are very effective at producing clean (<1%, <0.5%, or even <0.1% TDS) permeate. Even lower rejection systems result in even higher recovery percentages because their osmotic pressure is reduced and can be further purified by a second pass using membranes of the same or higher rejection, as shown in the subsequent figures.

[0173] Figures 6A-6D illustrate the range of operating pressures that can be used for reverse osmosis type concentration of weak black liquor, using the assumption of an ideal solution (undiluted). Low pressures (e.g., 800 psi) are not sufficient to produce high recovery ratios unless the liquor is relatively weak. High pressures (e.g., 1400 psi) can produce very high recovery ratios, even with these high rejection membranes and clean permeate (<0.1% or even 0.05% TDS).

[0174] 7A-7D illustrate the change in recovery ratio with membrane system size (more or fewer modules) for a fixed system feed rate. Recovery ratio is related to the amount and strength of the concentrate.

[0175] Additionally, the solution can be passed through two membranes. The permeate from the previous Figures 4-7D can then be passed between additional membranes to produce an even cleaner permeate. Thus, Figures 8A-8D show that a very clean permeate can be achieved with a membrane that rejects only 70% or more of divalent anions, such as sulfate anion. With very high rejection of divalent anions (90%-100%) and monovalent anions (80%-95%), a nearly completely clean permeate can be produced from this second membrane system.

[0176] 8A-8D only consider a fixed size of the membrane system for this second pass, while FIGS. 9A-9E show that when the size of the first system (and therefore the amount of permeate passed to the second system) is fixed, the size of the second system can be chosen to produce a high recovery ratio and a clean permeate (<1%, <0.5%, or <0.1% TDS). The maximum recovery observed in the lower panel is set by the size of the first system (750 modules at 1000 psi). These durable membranes are capable of producing high recovery (approximately 50%) and clean permeate.

[0177] While the present teachings have been described in conjunction with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments or examples. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents, as will be appreciated by those skilled in the art.

[0178] Although various embodiments of the present invention have been described and illustrated herein, those skilled in the art will readily envision various other means and / or structures for performing the functions and / or obtaining the results and / or one or more advantages described herein, and each of such variations and / or modifications is deemed to be within the scope of the embodiments of the present invention described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary, and that the actual parameters, dimensions, materials, and / or configurations will depend on the particular application(s) for which the teachings of the present invention are used. Those skilled in the art will recognize many equivalents to the specific embodiments of the present invention described herein. Thus, the foregoing embodiments are presented by way of example only, and it will be understood that, within the scope of the appended claims and their equivalents, the embodiments of the present invention may be practiced otherwise than as specifically described and claimed. The inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and / or method described herein. Furthermore, any combination of two or more such features, systems, articles, materials, kits, and / or methods is included within the inventive scope of the present disclosure, if such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent.

[0179] All definitions and those used herein should be understood to supersede any dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0180] The indefinite articles "a" and "an," as used herein in the specification and claims, unless clearly indicated to the contrary, should be understood to mean "at least one." All ranges cited herein are inclusive.

[0181] As used herein and in the claims, the term "aspect ratio" can be defined as the ratio of the in-plane lateral dimension to the thickness of the final product. For example, if a graphene oxide sheet has an average lateral dimension of 300 μm and a thickness of 200 nm, the ratio of the sheet size to thickness, or "aspect ratio," can be defined as 300,000 / 200, or 1.500.

[0182] As used throughout this specification and claims, the terms "substantially," "approximately," and "about" generally mean ±10% of the stated value, e.g., about 100 would include 90-110.

[0183] The term "and / or" as used in the specification and claims should be understood to mean "either or both" of the elements so conjoined, i.e., elements which may be present conjunctively or disjunctively. Multiple elements listed with "and / or" should be construed in the same manner, i.e., "one or more" of the elements so conjoined. Other elements may be included by the "and / or" clause. Other elements may optionally be present besides those specifically identified, whether or not related to those elements specifically identified. Thus, as a non-limiting example, when used in conjunction with open-ended language such as "comprising," a reference to "A and / or B" may refer in one embodiment to only A (optionally including elements other than B), in another embodiment to only B (optionally including elements other than A), in yet another embodiment to both A and B (optionally including other elements), etc.

[0184] As used herein and in the claims, "or" should be understood to have the same meaning as "and / or" defined above. For example, when separating items in a list, "or" or "and / or" is interpreted as being inclusive, i.e., including at least one (but including more than one) of a number or list of elements and optionally additional items not listed. Only terms clearly indicating the opposite, such as "only one of" or "exactly one of," or "consisting of," when used in the claims, will refer to the inclusion of exactly one element of a number or list of elements. In general, the term "or" as used herein is interpreted as indicating exclusive alternatives (i.e., "either one of," "one of," "only one of," or "exactly one of," when preceded by an exclusive term, such as "either," "one of," "only one of," or "exactly one of," as referring to an exclusive term. "Consisting essentially of," when used in the claims, shall have its ordinary meaning as used in the field of patent law.

[0185] As used in this specification and the claims, the phrase "at least one" in connection with a list of one or more elements should be understood to mean at least one element selected from any one or more of the elements in the list of elements, and does not necessarily include at least one of every element specifically listed in the list of elements, and does not exclude any combinations of elements in the list of elements. This definition also allows that elements other than the elements specifically identified in the list of elements to which the phrase "at least one" refers may optionally be present, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or in other words, "at least one of A or B" or in other words, "at least one of A and / or B") may refer in one embodiment to at least one A, optionally including more than one A, where B is not present (optionally including elements other than B); in another embodiment, to at least one B, optionally including more than one B, where A is not present (optionally including elements other than A); in yet another embodiment, to at least one A, optionally including more than one A and at least one B, optionally including more than one B, where A is not present (optionally including other elements);

[0186] In the claims, as well as in the above specification, all transitional phrases such as "comprising," "including," "carrying," "having," "containing," "involving," "holding," "composed of," and the like, are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases "consisting of" and "consisting essentially of" shall be closed or semi-closed transitional phrases, respectively, as set forth in the Patent Office Manual of Patent Examining Procedures, Section 2111.03.

[0187] As used herein, the term "graphene oxide sheet" refers to a single graphene oxide atomic layer or multiple graphene oxide atomic layers. Each may include out-of-plane chemical moieties attached to one or more carbon atoms on the layer. In some embodiments, the term "graphene oxide sheet" refers to 1 to about 20 graphene oxide atomic layers, e.g., 1 to about 18, 1 to about 16, 1 to about 14, 1 to about 12, 1 to about 10, 1 to about 8, 1 to about 6, 1 to about 4, or 1 to about 3 graphene oxide atomic layers. In some embodiments, the term "graphene oxide sheet" refers to 1, 2, or 3 graphene oxide atomic layers.

[0188] As used herein, the term "basic" means a pH greater than 7.

[0189] As used herein, "wt. %" refers to percent by weight.

[0190] As used herein, the term "flux" means the rate of flow. It represents the permeability of a membrane.

[0191] As used herein, the term "optionally substituted" is understood to mean that a given chemical moiety (e.g., an alkyl group) may (but need not) be attached to other substituents (e.g., heteroatoms). For example, an optionally substituted alkyl group may be a fully saturated alkyl chain (i.e., purely hydrocarbon). Alternatively, the same optionally substituted alkyl group may have a substituent other than hydrogen. For example, the group may be attached at any point along the chain to a halogen atom, a hydroxyl group, or any other substituent described herein. Thus, the term "optionally substituted" means that a given chemical moiety may contain other functional groups, but does not necessarily have additional functional groups. Suitable substituents used for optional substitution of the described groups include halogen, oxo, -OH, -CN, -COOH, -CH 2 CN, -O-(C 1 ~C 6 ) alkyl, (C 1 ~C 6 ) Alkyl, C 1 ~C 6 Alkoxy, (C 1 ~C 6 ) Haloalkyl, C 1 ~C 6 Haloalkoxy, -O-(C 2 ~C 6 ) alkenyl, -O-(C 2 ~C 6 ) alkynyl, (C 2 ~C 6 ) alkenyl, (C 2 ~C 6 ) Alkynyl, -OH, -OP(O)(OH) 2 , -OC(O)(C 1 ~C 6 ) alkyl, -C(O)(C 1 ~C 6 ) alkyl, -OC(O)O(C 1 ~C 6 ) Alkyl, -NH 2 , -NH((C 1 ~C 6 ) alkyl), -N((C 1 ~C 6 )Alkyl)2 , -NHC(O)(C 1 ~C 6 ) alkyl, -C(O)NH(C 1 ~C 6 ) alkyl, -S(O) 2 (C 1 ~C 6 ) alkyl, -S(O)NH(C 1 ~C 6 ) alkyl, and -S(O)N((C 1 ~C 6 )Alkyl) 2 These include, but are not limited to, the following: The substituents themselves can be optionally substituted.

[0192] As used herein, the term "hydroxy" or "hydroxyl" refers to the group -OH or -O - Refers to...

[0193] As used herein, "halo" or "halogen" refers to fluoro, chloro, bromo, and iodo.

[0194] The term "carbonyl" includes compounds and moieties which contain a carbon connected with a double bond to an oxygen atom. Examples of moieties containing carbonyl include, but are not limited to, aldehydes, ketones, carboxylic acids, amides, esters, anhydrides, and the like.

[0195] The term "carboxyl" refers to -COOH or its C 1 ~C 6 Refers to alkyl esters.

[0196] "Acyl" includes moieties that contain an acyl radical (RC(O)-) or a carbonyl group. "Substituted acyl" includes moieties in which one or more of the hydrogen atoms has been replaced with, for example, an alkyl group, an aryl group, or a cyclic group. quinyl groups, halogen, hydroxyl, alkylcarbonyloxy, arylcarbonyloxy, alkoxycarbonyloxy, aryloxycarbonyloxy, carboxylate, alkylcarbonyl, arylcarbonyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, alkylthiocarbonyl, alkoxyl, phosphate, phosphonato, phosphinato, amino (including alkylamino, dialkylamino, arylamino, diarylamino, and alkylarylamino), acylamino (including alkylcarbonylamino, arylcarbonylamino, carbamoyl, and ureido), amidino, imino, sulfhydryl, alkylthio, arylthio, thiocarboxylate, sulfate, alkylsulfinyl, sulfonato, sulfamoyl, sulfonamido, nitro, trifluoromethyl, cyano, azido, heterocyclyl, alkylaryl, or acyl groups substituted by aromatic or heteroaromatic moieties.

[0197] The term "alkoxy" or "alkoxyl" includes substituted and unsubstituted alkyl, alkenyl, and alkynyl groups covalently bonded to an oxygen atom. Examples of alkoxy groups or alkoxyl radicals include, but are not limited to, methoxy, ethoxy, isopropyloxy, propoxy, butoxy, and pentoxy groups. Examples of substituted alkoxy groups include halogenated alkoxy groups. Alkoxy groups can be substituted with groups such as alkenyl, alkynyl, halogen, hydroxyl, alkylcarbonyloxy, arylcarbonyloxy, alkoxycarbonyloxy, aryloxycarbonyloxy, carboxylate, alkylcarbonyl, arylcarbonyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, alkylthiocarbonyl, alkoxyl, phosphate, phosphonato, phosphinato, amino (including alkylamino, dialkylamino, arylamino, diarylamino, and alkylarylamino), acylamino (including alkylcarbonylamino, arylcarbonylamino, carbamoyl, and ureido), amidino, imino, sulfhydryl, alkylthio, arylthio, thiocarboxylate, sulfate, alkylsulfinyl, sulfonato, sulfamoyl, sulfonamido, nitro, trifluoromethyl, cyano, azido, heterocyclyl, alkylaryl, or aromatic or heteroaromatic moieties. Examples of halogen substituted alkoxy groups include, but are not limited to, fluoromethoxy, difluoromethoxy, trifluoromethoxy, chloromethoxy, dichloromethoxy, and trichloromethoxy.

[0198] The term "ester" includes compounds or moieties which contain a carbon or a heteroatom bound to an oxygen atom which is bonded to the carbon of a carbonyl group. The term "ester" includes alkoxycarboxy groups such as methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentoxycarbonyl, and the like.

[0199] As used herein, "amino" or "amine" refers to a primary (-NH 2 ), second class (-NHR x ), Grade 3 (-NR x R y ), or quaternary amines (-N + R x R y R z ) and R x , R y , and R z is independently an aliphatic, alicyclic, heteroaliphatic, heterocyclic, aryl, or heteroaryl moiety, as defined herein. Examples of amine groups include, but are not limited to, methylamine, dimethylamine, ethylamine, diethylamine, methylethylamine, isopropylamine, piperidine, trimethylamine, and propylamine. "Alkylamino" refers to -NH 2 The term "alkylamino" includes compounds in which the nitrogen of -NH is bonded to at least one alkyl group. Examples of alkylamino groups include benzylamino, methylamino, ethylamino, phenethylamino, and the like. "Dialkylamino" refers to a -NH 2 The nitrogen atom of the dialkylamino group is bonded to two alkyl groups. An example of a dialkylamino group is dimethylamino. and diethylamino. "Arylamino" and "diarylamino" include groups in which the nitrogen is bound to at least one or two aryl groups, respectively. "Aminoaryl" and "aminoaryloxy" refer to aryl and aryloxy substituted with amino. "Alkylarylamino", "alkylaminoaryl", or "arylaminoalkyl" refer to an amino group bound to at least one alkyl group and at least one aryl group. "Alkaminoalkyl" refers to an alkyl, alkenyl, or alkynyl group bound to a nitrogen atom which is also bound to an alkyl group. "Acylamino" includes groups in which the nitrogen is bound to an acyl group. Examples of acylamino include, but are not limited to, alkylcarbonylamino, arylcarbonylamino, carbamoyl, and ureido groups.

[0200] The term "amide" or "aminocarboxy" includes compounds or moieties that contain a nitrogen atom that is bonded to the carbon of a carbonyl or thiocarbonyl group. This term includes "alkaminocarboxy" groups that contain an alkyl, alkenyl, or alkynyl group bonded to an amino group that is bonded to the carbon of a carbonyl or thiocarbonyl group. This term also includes "arylaminocarboxy" groups that contain an aryl or heteroaryl moiety bonded to an amino group that is bonded to the carbon of a carbonyl or thiocarbonyl group. The terms "alkylaminocarboxy", "alkenylaminocarboxy", "alkynylaminocarboxy", and "arylaminocarboxy" include moieties in which the alkyl, alkenyl, alkynyl, and aryl moieties are each bonded to a nitrogen atom that is also bonded to the carbon of a carbonyl group. Amides can be substituted with substituents such as linear alkyl, branched alkyl, cycloalkyl, aryl, heteroaryl, or heterocycle. The substituents of the amide group may be further substituted.

[0201] Unless otherwise defined, the term "aryl" refers to a cyclic aromatic hydrocarbon group having one to three aromatic rings, including monocyclic or bicyclic groups such as phenyl, biphenyl, or naphthyl. When containing two aromatic rings (such as bicyclic), the aromatic rings of the aryl group can be attached at a single point (e.g., biphenyl) or fused (e.g., naphthyl). The aryl group can be optionally substituted at any point of attachment with one or more substituents, for example, 1 to 5 substituents. Exemplary substituents include -H, -halogen, -O-(C 1 ~C 6 ) alkyl, (C 1 ~C 6 ) alkyl, -O-(C 2 ~C 6 ) alkenyl, -O-(C 2 ~C 6 ) alkynyl, (C 2 ~C 6 ) alkenyl, (C 2 ~C 6 ) Alkynyl, -OH, -OP(O)(OH) 2 , -OC(O)(C 1 ~C 6 ) alkyl, -C(O)(C 1 ~C 6 ) alkyl, -OC(O)O(C 1 ~C 6 ) Alkyl, NH 2 , NH((C 1 ~C 6 ) alkyl), N((C 1 ~C 6 )Alkyl) 2 , -S(O) 2 -(C 1 ~C 6 ) alkyl, -S(O)NH(C 1 ~C 6 ) alkyl, and -S(O)N((C 1 ~C 6 )Alkyl) 2The substituents themselves can be optionally substituted. Furthermore, when containing two fused rings, the aryl groups defined herein can have a fully saturated ring and an unsaturated or partially saturated ring fused thereto. Exemplary ring systems of these aryl groups include, but are not limited to, phenyl, biphenyl, naphthyl, anthracenyl, phenalenyl, phenanthrenyl, indanyl, indenyl, tetrahydronaphthalenyl, tetrahydrobenzoannulenyl, and the like.

[0202] Unless otherwise defined, "heteroaryl" means a monocyclic aromatic radical of 5-24 ring atoms containing one or more ring heteroatoms selected from N, O, or S, with the remaining ring atoms being C. Heteroaryl as defined herein also refers to bicyclic heteroaromatic groups in which the heteroatoms are selected from N, O, or S. The aromatic radical may optionally be independently selected from one or more substituents as described herein. Examples include furyl, thienyl, pyrrolyl, pyridyl, pyrazolyl, pyrimidinyl, imidazolyl, isoxazolyl, oxazolyl, oxadiazolyl, pyrazinyl, indolyl, thiophen-2-yl, quinolyl, benzopyranyl, isothiazolyl, thiazolyl, thiadiazole, indazole, benzimidazolyl, thieno[3,2-b]thiophene, triazolyl, triazinyl, imidazo[1,2-b]pyrazolyl, furo[2,3-c]pyridinyl, imidazo[1,2-a]pyridinyl, indazolyl, pyrrolo[2,3-c]pyridinyl, pyrrolo[3,2-c]pyridinyl, pyrazolo[3,4-c]pyridinyl, thieno[3,2-c]pyridinyl, thieno[2,3-c]pyridinyl, thieno[2,3-b]pyridinyl, benzothiazolyl, indolyl, indolinyl, Indolinyl, dihydrobenzothiophenyl, dihydrobenzofuranyl, benzofuran, chromanyl, thiochromanyl, tetrahydroquinolinyl, dihydrobenzothiazine, dihydrobenzoxanyl, quinolinyl, isoquinolinyl, 1,6-naphthyridinyl, benzo[de]isoquinolinyl, pyrido[4,3-b][1,6]naphthyridinyl, thieno[2,3-b]pyrazinyl, quinolinyl Zolinyl, tetrazolo[1,5-a]pyridinyl, [1,2,4]triazolo[4,3-a]pyridinyl, isoindolyl, pyrrolo[2,3-b]pyridinyl, pyrrolo[3,4-b]pyridinyl, pyrrolo[3,2-b]pyridinyl, imidazo[5,4-b]pyridinyl, pyrrolo[1,2-a]pyrimidinyl, tetrahydropyrrolo[1,2-a]pyrimidinyl, 3,4-dihydro-2H-1λ 2-pyrrolo[2,1-b]pyrimidine, dibenzo[b,d]thiophene, pyridin-2-one, furo[3,2-c]pyridinyl, furo[2,3-c]pyridinyl, 1H-pyrido[3,4-b][1,4]thiazinyl, benzoxazolyl, benzisoxazolyl, furo[2,3-b]pyridinyl, benzothiophenyl, 1,5-naphthyridinyl, furo[3,2-b]pyridine, [1,2,4]triazolo[1,5-a]pyridinyl, benzo[1,2,3]triazolyl, imidazo[1,2-a]pyrimidinyl, [1,2,4]triazolo[4,3-b ]pyridazinyl, benzo[c][1,2,5]thiadiazolyl, benzo[c][1,2,5]oxadiazole, 1,3-dihydro-2H-benzo[d]imidazol-2-one, 3,4-dihydro-2H-pyrazolo[1,5-b][1,2]oxazinyl, 4,5,6,7-tetrahydropyrazolo[1,5-a]pyridinyl, thiazolo[5,4-d]thiazolyl, imidazo[2,1-b][1,3,4]thiadiazolyl, thieno[2,3-b]pyrrolyl, 3H-indolyl, and derivatives thereof. Additionally, when containing two fused rings, an aryl group as defined herein may have a fully saturated ring and a fused unsaturated or partially saturated ring. Exemplary ring systems of these heteroaryl groups include indolinyl, indolinonyl, dihydrobenzothiophenyl, dihydrobenzofuran, chromanyl, thiochromanyl, tetrahydroquinolinyl, dihydrobenzothiazine, 3,4-dihydro-1H-isoquinolinyl, 2,3-dihydrobenzofuran, indolinyl, indolyl, and dihydrobenzoxanyl.

[0203] Furthermore, the terms "aryl" and "heteroaryl" include polycyclic aryl and heteroaryl groups, e.g., tricyclic, bicyclic, such as naphthalene, benzoxazole, benzodioxazole, benzothiazole, benzimidazole, benzothiophene, quinoline, isoquinoline, naphtholidine, indole, benzofuran, purine, benzofuran, deazapurine, indolizine.

[0204] "Alkyl" refers to a straight or branched chain saturated hydrocarbon. 1 ~C 6 The alkyl group of C contains 1 to 6 carbon atoms. 1 ~C 6 Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, butyl, pentyl, isopropyl, isobutyl, sec- and tert-butyl, isopentyl, and neopentyl.

[0205] Optionally substituted alkyl refers to an unsubstituted alkyl or an alkyl group having one or more substituted aryl groups on the hydrocarbon backbone. "Alkyl" refers to an alkyl group having specified substituents replacing one or more hydrogen atoms on the carbon above. Such substituents can include, for example, alkyl, alkenyl, alkynyl, halogen, hydroxyl, alkylcarbonyloxy, arylcarbonyloxy, alkoxycarbonyloxy, aryloxycarbonyloxy, carboxylate, alkylcarbonyl, arylcarbonyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, alkylthiocarbonyl, alkoxyl, phosphate, phosphonato, phosphinato, amino (including alkylamino, dialkylamino, arylamino, diarylamino, and alkylarylamino), acylamino (including alkylcarbonylamino, arylcarbonylamino, carbamoyl, and ureido), amidino, imino, sulfhydryl, alkylthio, arylthio, thiocarboxylate, sulfate, alkylsulfinyl, sulfonato, sulfamoyl, sulfonamido, nitro, trifluoromethyl, cyano, azido, heterocyclyl, alkylaryl, or aromatic or heteroaromatic moieties.

[0206] As used herein, "alkenyl" includes unsaturated aliphatic groups analogous in length and possible substitution to the alkyls described above, but which contain at least one double bond. For example, the term "alkenyl" includes linear alkenyl groups (e.g., ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl), and branched alkenyl groups.

[0207] Optionally substituted alkenyl refers to an unsubstituted alkenyl or an alkenyl having specified substituents replacing one or more hydrogen atoms on one or more hydrocarbon backbone carbon atoms. Such substituents can include, for example, alkyl, alkenyl, alkynyl, halogen, hydroxyl, alkylcarbonyloxy, arylcarbonyloxy, alkoxycarbonyloxy, aryloxycarbonyloxy, carboxylate, alkylcarbonyl, arylcarbonyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, alkylthiocarbonyl, alkoxyl, phosphate, phosphonato, phosphinato, amino (including alkylamino, dialkylamino, arylamino, diarylamino, and alkylarylamino), acylamino (including alkylcarbonylamino, arylcarbonylamino, carbamoyl, and ureido), amidino, imino, sulfhydryl, alkylthio, arylthio, thiocarboxylate, sulfate, alkylsulfinyl, sulfonato, sulfamoyl, sulfonamido, nitro, trifluoromethyl, cyano, heterocyclyl, alkylaryl, or aromatic or heteroaromatic moieties.

[0208] "Alkynyl" includes unsaturated aliphatic groups analogous in length and possible substitution to the alkyls described above, but which contain at least one triple bond. For example, "alkynyl" includes linear alkynyl groups (e.g., ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, octynyl, nonynyl, decynyl) and branched alkynyl groups. In certain embodiments, a linear or branched chain alkynyl group has 6 or fewer carbon atoms in its backbone (e.g., C for a linear chain). 2 ~C 6 , for branched chains C 3 ~C 6 ). "C 2 ~C 6 The term "alkynyl" includes alkynyl groups containing 2 to 6 carbon atoms. 3 ~C 6 The term includes alkynyl groups containing three to six carbon atoms.

[0209] As used herein, the term "molecular weight cutoff" refers to a rejection rate of at least 90% (e.g., at least 92%, at least 95%, or at least 98%) for molecules having a molecular weight greater than the cutoff value.

[0210] As used herein, the term "room temperature" refers to about 15°C, about 16°C, about 17°C, about 18°C, about 19°C, about 20°C, about 21°C, about 22°C, about 23°C, about 24°C, or about 25°C. It may refer to a temperature of about 5° C. In some embodiments, room temperature is about 20° C.

[0211] As used herein, the term "substantially the same" refers to a first value that is within 10% of a second value. For example, if A is substantially the same as B and B is 100, then A can have a value in the range of 90-110. If A is substantially the same as B and B is 200, then A can have a value in the range of 180-220.

[0212] As used herein, the term "grayscale mode value" refers to the mode value of an image recorded using the RGB color model, which is obtained by first converting the image to grayscale using image processing software (e.g., ImageJ) using the following formula: gray = 0.299. * Red +0.587 * Green +0.114 * It is calculated by converting each pixel to grayscale using blue and then quantifying the mode of the distribution of pixel intensities.

[0213] The claims should not be read as limited to the described order or elements unless stated to that effect. It is understood that various changes in form and details can be made by those skilled in the art without departing from the spirit and scope of the appended claims. All embodiments that come within the spirit and scope of the following claims and equivalents are claimed. EXAMPLES

[0214] Example 1. Monofunctionalization with acrylamide Graphene oxide membranes were fabricated by the following procedure: (1) 15 mL of 4 mg / mL graphene oxide sheets were treated with 0.1 mL of TEA, 22 mg of NHS, and 72 mg of EDC. (2) The mixture was incubated at room temperature for 1 h. (3) A 5 mL aliquot of the mixture was treated with 10.6 mg of acrylamide. (4) The resulting mixture was heated in an oven at 65° C. for 4 h. (5) The mixture was cooled to room temperature. (6) The mixture was then cast onto a substrate with a 40-gauge rod, dried, and washed with DMF / water.

[0215] The durability test procedure is as follows: (1) cut a 47-50 mm disk from the graphene oxide membrane using a razor blade or laser cutter, (2) place the disk, graphene oxide side up, on a porous stainless steel frit, which is then attached to a Sterlitech HP4750 filtration cell, (3) add 60-100 mL of 1 wt% lactose solution, (4) place the construct on a stir plate at approximately 750 rpm, (4) close the feed chamber and pressurize it to 50-100 psi, (5) centrifuge the 1 wt% lactose and 0.1 wt% MgSO solution at room temperature using a driving pressure of 75 psi and a stirring speed of approximately 500 rpm. 4 Approximately 15-30 mL of the permeate of the solution is collected. (6) The membrane is then exposed to partial phosphate buffer at the exposure temperature for 4 hours and then retested for sugar and salt rejection.

[0216] Partial phosphate buffer is 500 mL of 0.025 M Na 2 HPO 4 (1.77 g in 500 mL) with 111 mL of 0.1 M NaOH (0.444 g in 111 mL). The mixture is sonicated to dissolve or allowed to stand overnight. The buffer is stored in a 4° C. refrigerator.

[0217] The film exhibited durability at an exposure temperature of 80°C.

[0218] Example 2. Monofunctionalization with acrylamide Graphene oxide films were prepared by the following procedure: (1) 15 mL of 4 mg / mL graphene oxide sheets were treated with 0.8 mL of TEA, 22 mg of NHS, and 72 mg of EDC. (2) The mixture was incubated at room temperature for 1 hour. (3) A 5 mL aliquot of the mixture was treated with 10.6 mg of acrylamide. (4) The resulting mixture was heated in an oven at 80° C. for 4 hours. (5) The mixture was cooled to room temperature. (6) The mixture was then cast onto a substrate with a 40-gauge rod, dried, and washed with DMF / ethanol.

[0219] The membranes were evaluated using the durability test procedure outlined in Example 1. The membranes exhibited an initial lactose rejection of 90% and 88% lactose rejection after exposure to a temperature of 80° C.

[0220] Example 3. Monofunctionalization with 2-(4-aminophenyl)ethanol Graphene oxide films were fabricated by the following procedure: (1) 5 mg of CsOH and 10 mg of 2-(4-aminophenyl)ethanol were dissolved in 0.2 mL of water. (2) The mixture was added to 3 mL of 4 mg / mL graphene oxide sheets. (3) The resulting mixture was heated in a 60° C. oven for 2 hours, followed by heating in an 80° C. oven for 19 hours. (4) The mixture was cooled to room temperature. (5) The mixture was then cast onto a substrate with a 40-gauge rod and allowed to dry.

[0221] The membranes were evaluated using the durability test procedure outlined in Example 1. The membranes exhibited an initial lactose rejection of 84% and a lactose rejection of 83% after exposure to a temperature of 50° C.

[0222] Example 4. Monofunctionalization with 4-aminophenethyl alcohol Graphene oxide membranes were prepared by the following procedure: (1) Mix 10 mL (4 mg / mL) of graphene oxide sheets with 5 mL of 1 M HCl. (2) Add 42 mg of 4-aminophenethyl alcohol to the mixture. (3) Add 69 mg of NaNO 2 Dissolve in 2 mL of water and add NaNO 2 The solution was added dropwise to the graphene oxide mixture. (4) Stir overnight. (5) Centrifuge at 5000 rpm for 5 minutes, decant the supernatant and replace with clean water. (6) Repeat step (5) a total of three times. (7) Vortex the mixture and cast it onto the substrate with a 40 gauge rod and allowed to dry.

[0223] The membranes were evaluated using the durability test procedure outlined in Example 1. The membranes exhibited an initial lactose rejection of 80% and a lactose rejection of 53% after exposure to a temperature of 50° C.

[0224] Example 5.4-Monofunctionalization with aminobenzoic acid Graphene oxide membranes were prepared by the following procedure: (1) Mix 10 mL (4 mg / mL) of graphene oxide sheets with 5 mL of 1 M HCl. (2) Add 46 mg of 4-aminobenzoic acid to the mixture. (3) Add 69 mg of NaNO 2 Dissolve in 2 mL of water and add NaNO 2 Add the solution dropwise to the graphene oxide mixture. (5) Centrifuge at 5000 rpm for 5 minutes. (6) Rinse with water three times and with ethanol once.

[0225] The membranes were evaluated using the durability test procedure outlined in Example 1. The membranes exhibited an initial lactose rejection of 82% and 75% lactose rejection after exposure to a temperature of 50° C.

[0226] Example 6. Improvement of pretreatment flux Flux was measured for 1 wt% lactose and 0.1 wt% MgSO before and after exposure to high temperature and pH. 4 Flux is measured during filtration testing using a filtration pressure of 75 pounds per square inch (psi). On average, flux is in the range of 0.3 to 0.6 gallons per square foot per day (GFD) at a supply pressure of 75 pounds per square inch (psi). The samples were exposed to partial phosphate buffered saline (PPB), pH 11.5, at 80°C for 4 hours. A significant increase in flux was observed after (elevated pH and temperature conditions).

[0227] Table 1 summarizes the flux results before and after exposure to the various conditions. When the temperature is increased from 25°C to 50°C, an improvement in flux of about 1.8 times is observed (Table 1, entry 1). After increasing the temperature from 50°C to 80°C, no further improvement in flux is observed (Table 1, entry 2). In both entries 1 and 2, the addition of 1 wt% lactose and 0.1 wt% MgSO4 4Exposure to high temperature is performed with a feedstock of 0.1 ml / kg and flux is measured at the temperatures specified in Table 1. In comparison, the combination of high temperature and pH results in about a 6-fold flux improvement (Table 1, entry 3), which is not lost when the temperature is reduced back to 25° C. When exposed to PPB at 80° C., the flux reaches 36 GFD, an approximately 72-fold improvement from the initial flux at 25° C. These results suggest that exposure to high temperature allows for a finite flux improvement, and exposure to high pH improves flux by about 3-fold over high temperature alone. All membranes discussed in this example and referenced in Table 1 meet the minimum lactose rejection of 50%.

[0228] [Table 1]

[0229] Example 7. Pressure durability The durability of the graphene oxide membrane at high pressure was evaluated. The graphene oxide membrane was placed on a 120 μm thick polyethersulfone support substrate and heated at a temperature of 80 °C and a pressure of 1000 psi in a 1 wt % lactose and 0.1 wt % MgSO 4 For testing purposes, the support substrate is mounted on a standard tricot permeable carrier (e.g., 0.012 inches thick, approximately 5 ounces per square yard, and 50 wales and 48 courses per inch).

[0230] Table 2 summarizes the results of the support substrate regarding the durability of the membrane under high pressure conditions.

[0231] [Table 2]

[0232] [Table 3]

[0233] Example 8. Quantification of membrane color The color of the graphene oxide films was characterized by recording images of the graphene oxide films and quantifying their grayscale mode values. Images of the graphene oxide films were collected in a light box with dimensions of 9.4 x 9.1 x 8.7 inches and two rows of 20 white LEDs on the top leading and trailing edges of the light box. The graphene oxide film sample to be photographed was placed in the center of the light box and images were captured at an angle of approximately 90° between the camera lens, the target, and the LED light source. The data presented was averaged for multiple samples. Color was quantified by converting the relative intensity of each pixel in the images from additive color model RGB to grayscale using image processing software (e.g., ImageJ) and comparing the intensity of the resulting signals plotted as pixel histograms. Each grayscale pixel histogram showed the distribution of gray values ​​for each image, with the x-axis representing the possible gray values ​​(0-255) and the y-axis representing the number of pixels found at each gray value. The greyscale mode value was calculated from the histogram, with grey values ​​closer to zero corresponding to a darker image and grey values ​​closer to 255 corresponding to a lighter image.

[0234] 13A-15H show the results of quantification using the methods described above.

Claims

1. A supporting substrate; A graphene oxide film disposed on the support substrate, the graphene oxide film comprises a plurality of graphene oxide sheets, each of the graphene oxide sheets being covalently bonded to a chemical spacer; the graphene oxide film has a first lactose rejection of at least 50% using a first 1 wt % lactose solution at room temperature; a graphene oxide membrane, wherein the graphene oxide membrane has a second lactose rejection of at least 50% using a second 1 wt% lactose solution at room temperature after contacting the graphene oxide membrane with a solution at least 80° C. for a period of time; A filtration device comprising:

2. 2. The filtration device of claim 1, wherein the second lactose rejection is substantially the same as the first lactose rejection.

3. 2. The filtration device of claim 1, wherein the second lactose rejection is greater than the first lactose rejection.

4. The filtration device according to any one of claims 1 to 3, wherein the first lactose rejection rate is 90% or less.

5. The filtration device according to any one of claims 1 to 4, wherein the second lactose rejection rate is 90% or less.

6. 6. The filtration device of claim 1, wherein each of the graphene oxide sheets is not covalently cross-linked to adjacent graphene oxide sheets.

7. The filtration device of any one of claims 1 to 6, wherein the chemical spacer comprises an amine or a derivative thereof.

8. The chemical spacer is -NH-R １ wherein R １ 8. The filtration device of claim 7, wherein is optionally substituted aryl.

9. The chemical spacer is -NH-C(O)-R ２ wherein R ２ Each of which is optionally replaceable C １ ~C ６ Alkyl or C ２ ~C ６ 8. The filtration device of claim 7, wherein the alkyl group is alkenyl.

10. 8. The filtration device of claim 7, wherein the amine is 4-aminophenylacetic acid or 2-(4-aminophenyl)ethanol.

11. The filtration device of any one of claims 1 to 6, wherein the chemical spacer comprises an amide or a derivative thereof.

12. 12. The filtration device of claim 11, wherein the amide is acrylamide, propionamide, isobutyramide, or pivalamide.

13. The filtration device of any one of claims 1 to 12, wherein the solution has a pH of about 7.

14. Filtration device according to any one of claims 1 to 12, wherein the solution has a pH of about 11. 。

15. The filtration device of any one of claims 1 to 12, wherein the solution has a pH of about 14.

16. The filtration device according to any one of claims 13 to 15, wherein the solution is a phosphate buffer solution.

17. The phosphate buffer solution contains Na ２ H.P.O. ４ 17. The filtration device of claim 16, comprising:

18. The filtration device according to any one of claims 1 to 17, wherein the graphene oxide film is contacted with the solution at 100°C or less.

19. The filtration device according to any one of claims 1 to 18, wherein the room temperature is about 20°C.

20. The filtration device of any one of claims 1 to 19, wherein the solution passes through the graphene oxide membrane.

21. The filtration device according to any one of claims 1 to 20, wherein the period of time is about 2 to 6 hours.

22. A supporting substrate; A graphene oxide film disposed on the support substrate, the graphene oxide film comprises a plurality of graphene oxide sheets, each of the graphene oxide sheets being covalently bonded to a chemical spacer; the graphene oxide film has a first lactose rejection of at least 50% using a first 1 wt % lactose solution at room temperature; a graphene oxide membrane, wherein the graphene oxide membrane has a second lactose rejection of at least 50% using a second 1 wt % lactose solution at room temperature after contacting the graphene oxide membrane with a solution having a pH of at least 11 for a period of time at room temperature; A filtration device comprising:

23. 23. The filtration device of claim 22, wherein the pH is at least about 12.

24. 23. The filtration device of claim 22, wherein the pH is at least about 14.

25. 25. The filtration device of any one of claims 22 to 24, wherein the second lactose rejection is substantially the same as the first lactose rejection.

26. 25. The filtration device of any one of claims 22 to 24, wherein the second lactose rejection is greater than the first lactose rejection.

27. The filtration device according to any one of claims 22 to 26, wherein the first lactose rejection rate is 90% or less.

28. The filtration device according to any one of claims 22 to 27, wherein the second lactose rejection rate is 90% or less.

29. 29. The filtration device of any one of claims 22 to 28, wherein each of the graphene oxide sheets is not covalently cross-linked to adjacent graphene oxide sheets.

30. The filtration device of any one of claims 22 to 29, wherein the chemical spacer comprises an amine or a derivative thereof.

31. The chemical spacer is -NH-R １ wherein R １ 31. The filtration device of claim 30, wherein is optionally substituted aryl.

32. The chemical spacer is -NH-C(O)-R ２ wherein R ２ Each of which is optionally replaceable C １ ~C ６ Alkyl or C ２ ~C ６ 31. The filtration device of claim 30, wherein the alkyl group is alkenyl.

33. 31. The filtration device of claim 30, wherein the amine is 4-aminophenylacetic acid or 2-(4-aminophenyl)ethanol.

34. The filtration device of any one of claims 22 to 29, wherein the chemical spacer comprises an amide or a derivative thereof.

35. 35. The filtration device of claim 34, wherein the amide is acrylamide, propionamide, isobutyramide, or pivalamide.

36. The solution is Na ２ H.P.O. ４ The filtration device according to any one of claims 22 to 35, comprising:

37. The filtration device according to any one of claims 22 to 36, wherein the room temperature is about 20°C.

38. The filtration device of any one of claims 22 to 37, wherein the solution passes through the graphene oxide membrane.

39. The filtration device according to any one of claims 22 to 38, wherein the solution is a buffer solution.

40. 40. The filtration device of any one of claims 22 to 39, wherein the period of time is about 2 to 6 hours.

41. a supporting substrate, the supporting substrate having a thickness of at least about 150 μm and a Young's modulus of at least about 0.9 GPa; A graphene oxide film disposed on the support substrate, the graphene oxide film comprises a plurality of graphene oxide sheets, each of the graphene oxide sheets being covalently bonded to a chemical spacer; the graphene oxide film has a first lactose rejection of at least 50% using a first 1 wt % lactose solution at room temperature; a graphene oxide membrane, wherein the graphene oxide membrane has a second lactose rejection of at least 50% using a second 1 wt % lactose solution at room temperature after subjecting the graphene oxide membrane to a pressure of about 1000 psi for a period of time; A filtration device comprising:

42. 42. The filtration device of claim 41, wherein the support substrate has a thickness of about 500 μm or less.

43. 43. The filtration device of claim 41 or 42, wherein the support substrate has a Young's modulus of about 2.5 GPa or less.

44. 44. The filtration device of any one of claims 41 to 43, wherein the support substrate comprises polypropylene, polyolefin, polyethersulfone (PES), polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN), nylon, or a combination thereof.

45. 45. A method for treating black liquor, the method comprising flowing black liquor through a filtration apparatus according to any one of claims 1 to 44, the black liquor comprising lignin, sodium sulfate, sodium carbonate, sodium hydrosulfide, sodium thiosulfate, sodium hydroxide, or combinations thereof.

46. 46. ​​The method of claim 45, wherein at least 50% of the lignin, sodium sulfate, sodium carbonate, sodium hydrosulfide, sodium thiosulfate, or sodium hydroxide is rejected by the graphene oxide membrane.

47. 1. A method for increasing the flux of a graphene oxide film comprising a plurality of graphene oxide sheets, each of the graphene oxide sheets being covalently bonded to a chemical spacer, the method comprising contacting the graphene oxide film with a solution that is at least about 50° C. for a period of time, wherein after the contacting step, the flux is increased by at least 50%.

48. 1. A method for increasing the flux of a graphene oxide film comprising a plurality of graphene oxide sheets, each of the graphene oxide sheets being covalently bonded to a chemical spacer, the method comprising contacting the graphene oxide film with a solution having a pH of at least about 10 for a period of time, wherein after the contacting step, the flux is increased by at least 50%.

49. 49. The method of claim 47 or 48, wherein the flux is increased by at least 1-fold after the contacting step.

50. 50. The method of any one of claims 47 to 49, wherein each of the graphene oxide sheets is not covalently cross-linked to adjacent graphene oxide sheets.

51. The method of any one of claims 47 to 50, wherein the chemical spacer comprises an amine or a derivative thereof.

52. The chemical spacer is -NH-R １ wherein R １ 52. The method of claim 51 , wherein is optionally substituted aryl.

53. The chemical spacer is -NH-C(O)-R ２ wherein R ２ Each of which is optionally replaceable C １ ~C ６ Alkyl or C ２ ~C ６ 52. The method of claim 51, wherein said alkyl group is alkenyl.

54. 52. The method of claim 51, wherein the amine is 4-aminophenylacetic acid or 2-(4-aminophenyl)ethanol.

55. The method of any one of claims 47 to 50, wherein the chemical spacer comprises an amide or a derivative thereof.

56. 56. The method of claim 55, wherein the amide is acrylamide, propionamide, isobutyramide, or pivalamide.

57. 48. The method of claim 47, wherein the solution has a pH of about 7.

58. 48. The method of claim 47, wherein the solution has a pH of at least about 10.

59. 54. The method of claim 53, wherein the solution is a phosphate buffer.

60. The phosphate buffer solution contains Na ２ H.P.O. ４ 60. The method of claim 59, comprising:

61. 61. The method of any one of claims 47 to 60, wherein the graphene oxide film is contacted with the solution at or below 100°C.

62. 62. The method of any one of claims 47 to 61, wherein the solution is passed through the graphene oxide membrane.

63. 63. The method of any one of claims 47 to 62, wherein the period of time is about 2 to 6 hours.

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