Functionalized transition metal dichronides and their use for desination of

Abstract

Disclosed herein is a film formed from a stack of transition metal disulfide (TMD) nanomonolayers, wherein the TMD is functionalized with a sulfur group. The membranes are characterized by having a network of water permeable capillary channels, each capillary channel having a width of about 4.5-5.5 angstroms, a contact angle for surface wettability of about 64-90 degrees, a degree of functionalization of about 10-15%, a degree of expansion of about 0.5-4.0%, and a thickness of about 200-1,300 nanometers. A method for removing ions from a fluid is also disclosed. The method includes passing the foregoing fluid through the membrane of the present disclosure in a forward osmosis manner.

Description

Cross-reference

[0001] This application claims all of the rights and contents of U.S. Provisional Application No. 63 / 553.556, filed on February 14, 2024. Background of the Invention 1. Field of the Invention

[0002] The present invention generally relates to membranes formed from stacks of transition metal dichalcogenide (TMD) nano-monolayers and methods for desalinating seawater using the same.

[0003] 2. Prior Art

[0004] Generating usable freshwater from seawater or wastewater is a promising approach to addressing water scarcity in water-scarce regions. Semipermeable membranes offer advantages over other desalination methods due to their energy efficiency, reduced carbon footprint, and durability. Nanomaterials are suitable for membrane fabrication due to their inherent selective screening capabilities. Two-dimensional membranes, including graphene oxide (GO), MXenes, and transition metal dichalcogenides (TMDs), possess inherent nanochannels, offering great potential for screening molecules or ions (such as sodium, potassium, or micropollutants). Specifically, GO laminates provide pores that allow water molecules to pass through while blocking hydrated mineral ions of a certain molecular weight. However, GO laminates readily swell in solution, leading to increased interlayer spacing and uncontrolled microstructural collapse. MXenes also face similar swelling issues due to their hydrophilic surface functional groups. While microstructural instability can be a useful tool in some situations, it is disadvantageous for membrane-related applications due to irreversible degradation and reduced performance. Several approaches have been proposed to address the microstructural instability of GO or MXenes, such as physical confinement, cation manipulation, or charge compensation. However, these approaches are often complex and impose additional costs for the specific application being pursued.

[0005] TMD materials, particularly molybdenum disulfide (MoS2) laminates, are more stable than GO or MXenes, making them a promising candidate for membrane fabrication. Over the past decade, researchers have investigated the use of MoS2 nanolayers for gas or solute separation applications. However, prototype MoS2 nanolayers with near-ideal stacking exhibit dense channels between successive layers, making them unsuitable for mass transfer. The capillary channel width (defined as δ) of MoS2 membranes is crucial for their screening and permeation performance. By manipulating the physical dimensions and surface chemistry of the MoS2 nanolayers, the nanochannels of nanolaminated membranes can be optimized, making them a viable path for practical MoS2 membrane applications. Forward osmosis (FO) relies on its own osmotic pressure to induce the movement of liquid from the low-concentration end (feed) across a semipermeable membrane to the high-concentration end (extract). Therefore, compared with pressure-driven technologies such as reverse osmosis (RO), nanofiltration (NF), and ultrafiltration (UF), FO has many potential advantages, including lower input energy, reduced scaling, and higher water recovery.

[0006] In view of this, the relevant field urgently needs to develop an improved MoS2 membrane that can be used for continuous water desalination. Summary of the Invention

[0007] Embodiments of the present invention relate to membranes composed of stacked nano-monolayers of transition metal dichalcogenides (TMDs) functionalized with sulfur groups, which can remove ions from fluids by forward osmosis (FO).

[0008] The primary object of the present invention is to provide a membrane comprising TMD monolayer nanosheets functionalized with thio groups, wherein the TMD monolayer nanosheets functionalized with thio groups are generated by reacting a TMD nanomonolayer dispersion with a sulfur-containing compound, wherein the sulfur-containing compound is cysteine, 1-propanethiol, or 3-mercaptopropane-1,2-diol; and the membrane is characterized by having a water-permeable capillary channel network, each capillary channel having a width of approximately 4.5-5.5 angstroms, a surface wettability contact angle of approximately 64-90 degrees, a functionalization degree of approximately 10-15%, a swelling degree of approximately 0.5-4.0%, and a thickness of approximately 200-1,300 nanometers.

[0009] According to an embodiment of the present invention, the TMD nano-monolayer dispersion is prepared by the following steps: (i) discharging the TMD bulk material in a lithium battery to produce a lithiated TMD bulk material; (ii) ultrasonically vibrating the lithiated TMD bulk material in water to exfoliate the lithiated TMD bulk material into a TMD nano-monolayer; (iii) collecting the product of step (ii) by centrifugation; and redispersing the product of step (iii) in water. In (iv), the TMD nanomonolayer dispersion is obtained.

[0010] According to an embodiment of the present invention, the TMD nano-monolayer is a MoS2 nano-monolayer.

[0011] According to an embodiment of the present invention, the sulfur-containing compound is 1-propanethiol; and the width of each capillary channel in the water-permeable capillary channel network of the membrane is about 5.2 angstroms, the contact angle of the surface wettability is about 90 degrees, the functionalization degree is about 10%, and the swelling degree is about 0.6%.

[0012] According to a further embodiment of the present invention, the sulfur-containing compound is cysteine; and the width of each capillary channel in the water-permeable capillary channel network of the membrane is about 5.1 angstroms, the contact angle of the surface wettability is about 65 degrees, the degree of functionalization is about 14%, and the swelling degree is about 1.3%.

[0013] According to other embodiments of the present invention, the sulfur-containing compound is 3-mercaptopropane-1,2-diol; and the width of each capillary channel in the water-permeable capillary channel network of the membrane is approximately 4.7 angstroms, the contact angle of the surface wettability is approximately 70 degrees, the degree of functionalization is approximately 10%, and the swelling is approximately 3.7%.

[0014] Therefore, a second object of the present invention is to provide a method for removing ions from a fluid, comprising passing the fluid through the membrane of the present invention by forward osmosis for at least 24 hours.

[0015] According to an embodiment of the present invention, the membrane is formed by stacking TMD nano-monolayers thiolated with 1-propanethiol, and the width of each capillary channel in the water-permeable capillary channel network of the membrane is approximately 5.2 angstroms, the contact angle of the surface wettability is approximately 90 degrees, the degree of functionalization is approximately 10%, and the swelling degree is approximately 0.6%.

[0016] According to certain embodiments of the present invention, the membrane is formed by stacking TMD nanomonolayers sulfylated with cysteine; and the width of each capillary channel in the water-permeable capillary channel network of the membrane is approximately 5.1 angstroms, the contact angle of the surface wettability is approximately 65 degrees, the degree of functionalization is approximately 14%, and the swelling degree is approximately 1.3%.

[0017] According to other embodiments of the present invention, the membrane is composed of a stack of TMD nanomonolayers sulfhydrylated with 3-mercaptopropane-1,2-diol; and the width of each capillary channel in the water-permeable capillary channel network of the membrane is approximately 4.7 angstroms, the contact angle of the surface wettability is approximately 70 degrees, the degree of functionalization is approximately 10%, and the swelling degree is approximately 3.7%.

[0018] According to an embodiment of the present invention, the fluid contains ions selected from the group consisting of sodium ions, potassium ions, magnesium ions, calcium ions, and combinations thereof.

[0019] According to an embodiment of the present invention, the membrane can remove at least 90% of the ions in the fluid.

[0020] Details of one or more embodiments of the present invention can be found in the following detailed description of the invention. Other features and advantages of the present invention can also be found in the detailed description of the invention and the scope of claims. Simple illustration

[0021] The details of the present invention can be better understood through the following drawings and their descriptions, wherein

[0022] Figure 1 is a bar graph showing contact angle measurement results of an unfunctionalized MoS2 film and three functionalized MoS2 films according to an embodiment of the present invention;

[0023] Figure 2 is a bar graph showing expansion properties of different two-dimensional materials (e.g., GO or MXene) films and functionalized MoS2 films according to an embodiment of the present invention;

[0024] Figure 3 is a line graph showing water flux (dashed line) and sodium ion removal (dashed-dotted line) of unfunctionalized MoS2 membranes and functionalized MoS2 membranes of different thicknesses according to an embodiment of the present invention;

[0025] Figure 4 is a graph showing the change in water flux of a functionalized MoS2 membrane after several cycles according to an embodiment of the present invention;

[0026] Figure 5 is a bar graph showing the removal of five salts from a 600 nm thick functionalized MoS2 film according to an embodiment of the present invention;

[0027] Figure 6 is a comparison chart of water flux and sodium ion removal results under forward osmosis (FO) of the functionalized MoS2 membrane (asterisk) and other 2D materials according to an embodiment of the present invention;

[0028] Figure 7 1 is a graph showing the long-term sodium ion permeability of a functionalized MoS2 membrane under forward osmosis (FO) according to an embodiment of the present invention;

[0029] Figure 8 is a graph showing the permeability of potassium, sodium, calcium, and magnesium ions using synthetic seawater as feed according to an embodiment of the present invention;

[0030] Figure 9 is a graph showing the ion removal results of a functionalized MoS2 membrane (600 nm thick) after filtering synthetic seawater for 100 hours according to an embodiment of the present invention; and

[0031] Figure 10 Capillary channel width and ion removal capacity. (a) Changes in capillary channel width of dried functionalized MoS2 membranes and after immersion in deionized water or salt solutions of varying concentrations (NaCl, KCl, Na2SO4, MgCl2, and CaCl2) for 24 hours; effects of sodium (b), potassium (c), calcium (d), and magnesium (e) removal on capillary width in the corresponding solutions; (f) Changes in the full width at half maximum (FWHM) of the XRD peaks of the three functionalized MoS2 membranes in different solutions. Each error bar corresponds to the standard deviation of at least three samples. Detailed Description of the Invention

[0032] The following describes an embodiment of the present invention in detail with reference to the accompanying drawings. This disclosure relates to a method for preparing a functionalized MoS2 membrane and its application in desalination of seawater.

[0033] 1. Film of the present invention

[0034] The primary objective of this invention is to provide a membrane composed of stacked TMD nanolayers functionalized with sulfide groups. Vacant sulfur atoms in the TMD nanolayers are grafted with sulfide groups, creating a channel structure that allows water molecules to pass through. Consequently, the membrane can be used as an ion sieve to remove ions from fluids such as seawater.

[0035] To prepare the desired membrane, the TMD nanomonolayer is modified by grafting multiple sulfur groups at the sulfur atom vacancies of the TMD nanomonolayer to create a channel structure between continuous nanolayers. According to the embodiment of the present disclosure, the TMD nanomonolayer dispersion is reacted with a sulfur-containing compound in water or an organic solution for at least 24 hours. The choice of suitable solvent varies depending on the sulfur-containing compound selected in the functionalization reaction. Examples of the sulfur-containing compound include, but are not limited to, cysteine, 1-propanethiol, and 3-mercaptopropane-1,2-diol. According to an embodiment of the present invention, the TMD nanomonolayer dispersion is prepared by the following steps: (i) discharging the TMD bulk material in a lithium battery to produce a lithiated TMD bulk material; (ii) ultrasonically vibrating the lithiated TMD bulk material in water to exfoliate the lithiated TMD bulk material into a TMD nano-monolayer; (iii) collecting the product of step (ii) by centrifugation; and redispersing the product of step (iii) in water. In (iv), the TMD nanomonolayer dispersion is obtained.

[0036] Examples of TMDs suitable for fabricating the films of the present invention include, but are not limited to, MoS2, TaS2, WS2, TiS2, MoSe2, WSe2, MoTe2, WTe2, NbS2, ReS2, NbSe2, ReSe2, NbTe2, ReTe2, NiS2, NiSe2, PdS2, ZrSe2, PdSe2, ZrTe2, PdTe2, TaSe2, TaTa2, TiSe2, and the like. According to a preferred embodiment of the present invention, the films of the present invention are fabricated by functionalizing a MoS2 nanomonolayer.

[0037] According to a preferred embodiment of the present invention, the film produced has the following characteristics: i. having a water-permeable capillary channel network, wherein the width of each capillary channel is about 4.5-5.5 angstroms, for example, about 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4 or 5.5 angstroms; ii. a surface wettability having a contact angle of about 64-90 degrees, for example, about 64, 65, 66, 67, 68, 69, 7, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89 or 90 degrees; iii. a functionalization degree of about 10-15%, for example, about 10, 11, 12, 13, 14 or 15%; iv. an overrun of about 0.5-4.0%, for example, about 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9 or 4.0%; and v. A thickness of about 200-1,300 nm, for example, about 200, 300, 400, 500, 600, 700, 800, 900, 1,000, 1,100, 1,200 or 1,300 nm.

[0038] According to a specific embodiment of the present invention, the TMD nanomonolayer dispersion was allowed to react with 1-propanethiol in an organic solution comprising a 2:1 volume ratio of water and dimethyl sulfoxide (DMSO) for 24 hours to form the desired membrane. The resulting membrane features a network of water-permeable capillary channels, each with a width of approximately 5.2 angstroms, a surface wettability contact angle of approximately 90 degrees, a functionalization level of approximately 10%, and a swelling rate of approximately 0.6%.

[0039] According to certain embodiments of the present invention, the TMD nanomonolayer dispersion is reacted with cysteine in an organic solution to form the desired membrane 24 hours later; and the resulting membrane is characterized by a water-permeable capillary channel network, each capillary channel having a width of approximately 5.1 angstroms, a surface wettability contact angle of approximately 65 degrees, a functionalization degree of approximately 14%, and a swelling degree of approximately 1.3%.

[0040] According to a further embodiment of the present invention, the TMD nanomonolayer dispersion is reacted with 3-mercaptopropane-1,2-diol in an organic solution to generate the desired membrane 24 hours later; and the resulting membrane is characterized by a water-permeable capillary channel network, each capillary channel having a width of approximately 4.7 angstroms, a surface wettability contact angle of approximately 70 degrees, a functionalization degree of approximately 10%, and a swelling degree of approximately 3.7%.

[0041] 2. Use of the membrane of the present invention to remove charged or uncharged solutes from fluids

[0042] The membranes of the present invention are characterized by a network of water-permeable capillary channels, each of which is approximately 4.5-5.5 angstroms wide. Therefore, the membranes of the present invention are suitable for removing charged or uncharged solutes from fluids, for example, through gravity filtration, forward osmosis (FO), and similar methods. According to specific embodiments of the present invention, by passing a fluid (e.g., seawater, brackish water, etc.) through the membranes of the present invention for at least 24 hours, greater than 96% of the solutes in the fluid are removed.

[0043] According to an embodiment of the present invention, the membrane functionalized with sulfur groups (i.e., MoS2-prop membrane) was grafted onto the MoS2 nano-monolayer by reaction with 1-propanethiol, and the water permeation rate under FO was 54.1 mol / m 2 According to another embodiment of the present invention, the water permeation rate is 35.7 mol / m2 by reacting with 3-mercaptopropane-1,2-diol to be grafted onto the MoS2 nano-monolayer to form the sulfhydryl-functionalized membrane of the present invention (i.e., MoS2-merc membrane). 2 / h, as for the membrane functionalized with sulfur groups (i.e., MoS2-cyst membrane) through the reaction with cysteine and grafted to the MoS2 nano-monolayer, the water permeation rate was 43.3 mol / m2 / h,.

[0044] Examples of charged solutes that may be present in the fluid include, but are not limited to, Na + , K + , Ca 2+ , Mg 2+ and the like. According to certain embodiments of the present invention, a membrane having a thickness of about 200 nanometers can remove at least 96% of the charged solutes in a fluid, for example, at least about 96%, 97%, 98% or 99% of the charged solutes. According to other embodiments of the present invention, a membrane having a thickness of about 600 nanometers can remove at least 99% of the charged solutes in a fluid, for example, at least about 99.1%, 99.2% or 99.3% of the charged solutes. According to further embodiments of the present invention, a membrane having a thickness of about 1,300 nanometers can remove at least 99.5% of the charged solutes in a fluid, for example, at least about 99.5%, 99.6%, 99.7% or 99.8% of the charged solutes. According to other embodiments of the present invention, the membrane of the present invention can also remove uncharged solutes (e.g., dyes) in sulfur bodies.

[0045] The present invention will be described below based on embodiments. The embodiments provided are merely examples, and the scope of the present invention is not limited to the disclosed embodiments. Example

[0046] Materials and Methods

[0047] Exfoliated MoS2 bulk powder

[0048] The electrochemical exfoliation lithium intercalation technique is used to exfoliate the MoS2 bulk powder into flakes. Briefly, a slurry containing MoS2 bulk powder, carbon black, and polyvinylidene fluoride (PVDF) (8:1:1) is mixed with N-methyl-2-pyrrolidone to form an electrode. The resulting button cell is used as the cathode and then discharged to induce lithium intercalation. After the discharge is completed, the cathode with lithium intercalation (Li x After removing the MoS2 nanosheet, ultrasonic vibration is performed in deionized water to obtain a MoS2 monolayer. This process generates hydrogen gas, further accelerating the exfoliation process. The exfoliated monolayer is collected by centrifugation and resuspended in deionized water. This step is repeated three times to remove MoS2 nanosheets with multi-layer or multi-layer structures.

[0049] Functionalization of MoS2 monolayer

[0050] The MoS2 monolayer was sulfylated using a sulfur-containing compound (i.e., cysteine, 1-propanethiol, or 3-mercaptopropane-1,2-diol) in an aqueous or organic solution. Specifically, the sulfur-containing compound was dissolved in deionized water or an organic solution (deionized water: dimethyl sulfoxide = 2:1) to prepare a 10 mM solution. This solution was then added to the MoS2 monolayer dispersion and allowed to react for 24 hours.

[0051] Preparation of films composed of functionalized MoS2 monolayer stacks

[0052] The functionalized MoS2 monolayer is collected by vacuum filtration onto a polymer substrate (nylon or PVDF) with pores of approximately 220 nm and a diameter of approximately 25 μm, thereby forming the membrane of the present invention. The thickness of the MoS2 membrane can be varied by changing the volume of the filtrate. MoS2 membranes sulfhydrylated with cysteine, 1-propanethiol, or 3-mercaptopropane-1,2-diol are respectively referred to as MoS2-cyst membranes, MoS2-prop membranes, or MoS2-merc membranes. Excess reactants are removed from the membrane by washing with ethanol (3 times, 20 ml each) and water (3 times, 20 ml each). Furthermore, since 1-propanethiol is dissolved in a mixed solution of DMSO, additional Raman spectroscopy testing is required to ensure that the DMSO has been completely removed. Finally, the membrane is dried at atmospheric pressure for later use.

[0053] Preparation of GO membrane and MXene membrane

[0054] A MXene nanolayer was prepared according to a method previously disclosed in the literature (Ding et al., Nat. Commun. 2018, 9(1), 155), and the MXene nanolayer solution was filtered and collected on a substrate to form a MXene membrane. A GO nanolayer was synthesized according to a method previously disclosed in the literature (Marcano et al., ACS Nano 2010, 4(8), 4806-4814; Mei et al., Analyst 2020, 145(10), 3749-3756), and the purified GO nanolayer was dispersed in deionized water. The solution was filtered and collected on a PVDF to form a GO membrane.

[0055] Feature Analysis

[0056] Scanning electron microscopy (SEM, TESCAN MIRA4) was used to capture top and side views of the functionalized membranes. Transmission electron microscopy (TEM) and energy distribution X-ray spectroscopy (EDS) were performed on a Tecnai G2 spirit Twin operating at 200 keV. X-ray diffractometers were used on a Bruker D2 PHASER (Cu Kα radioactive source, ). Atomic force microscopy (AFM) images were recorded in a Dimension 3100 (Veeco, CA). Fourier transform infrared (FT-IR) spectroscopy scans were performed in a PerkinElmer Spectrum II FT-IR spectrometer. Raman spectroscopy scans were performed in a WITEC 300R with an excitation wavelength of 532 nm. X-ray photoelectrometry (XPS) scans were performed in a ThermoScientific K-Alpha Nexsa and calibrated with the reference carbon 1s peak at 284.6 eV. The zeta potential of aqueous solutions was determined in a Malvern Zetasizer nano series at neutral pH. Contact angles were measured in a DataPhysics contact angle tester. Absorption spectra measured in a UV-visible spectrometer were obtained using a HITACHI UH4150 instrument. Solid-state 13 C CP MAS NMR experiments were performed on a Bruker 700 MHz (16.4 T) spectrometer at a frequency of 176.05 MHz with a Bruker MAS probe spinning at 10 kHz. 13 C solution NMR measurements were performed on a Bruker 400 MHz spectrometer. X-band electron paramagnetic resonance (EPR) spectra were acquired at room temperature on a Bruker EMXplus spectrometer using 5 mg of functionalized MoS2 films and prototype exfoliated MoS2. HAADF-STEM images were acquired on a FEITan Themis G2 200 probe double-spherical aberration (Cs)-calibrated scanning transmission electron microscope operated at an accelerating potential of 60 keV.

[0057] Forward osmosis filtration of salts and dyes

[0058] To investigate the efficiency of forward osmosis filtration in removing salts and dyes, water permeation tests were conducted using a customized U-shaped apparatus at room temperature (25°C ± 0.4°C). The U-shaped apparatus consists of two sections: a feed side and an extraction side, with the functionalized MoS2 membrane of the present invention firmly fixed in the center. Initially, the feed chamber and extraction chamber were filled with 0.5 M sodium chloride solution and 2 M sucrose solution, respectively, to the same height. Magnetic stir bars were installed in both chambers to minimize concentration polarization, and the average water permeation was measured three times in each chamber. Long-cycle water permeation tests were repeated using the same apparatus. For dyes, the feed side solution was replaced with 3.5 mM test dyes (rhodamine B, methyl blue, or methyl orange), while the extraction side solution remained unchanged. Concentrations on the extraction side were measured at room temperature using a conductivity meter and inductively coupled plasma optical emission spectrometry (ICP-OES). UV-visible (UV-Vis) spectroscopy was used to quantify dye concentrations according to the Lambert-Beer law.

[0059] All measurements were repeated three times. The water flux (J) was calculated using the following equations (1) and (2). w , molm - 2 h -1 bar -1 ) and salt flux (J s , mol m -2 h -1 ): where ρ is the density of water, ΔV is the volume added to the extraction side, V is the total volume on the extraction side, c is the salt concentration obtained from the calibration curve, A is the effective surface area of the membrane and Δt is the permeation time.

[0060] Calculate the osmotic pressure according to the following equation: Δπ=M×R×T (3) Where M is the molar concentration difference between the extract and the feed solution (including cations and anions, mol / L), R is the gas theorem constant (0.0821 L·bar·K -1 ·mol -1 ) and T is the Kelvin temperature during the test (298K).

[0061] J w / J sThe water / salt selectivity is calculated, and the upper limit is plotted based on a previously published method (Yang et al., J. Membr. Sci. 2019, 590, 117297). It should be noted that due to the presence of an extraction side in a forward osmosis system, the method for calculating seawater and dye removal in a forward osmosis system differs from that in a reverse osmosis operation. To account for dilution caused by the extraction solution, the actual concentration of the permeate or dye is estimated using the following equation: Among them C D is the salt or dye concentration measured on the extraction side, V D is the volume of the extraction solution. V P Represents the volume of permeate solution, which is the volume added to the extraction side. The removal rate is calculated according to the following equation:

[0062] Long-term stability of forward osmosis testing

[0063] The membrane was tested for long-term (100-hour) ion permeability in an H-shaped cell similar to the customized U-shaped device. The feed and extraction sides were filled with 2M sucrose solution to the same height. The extraction side solution was collected every 20 hours and analyzed three times by ICP-OES to evaluate the Na + , K + , Ca 2+ , Mg 2+ concentration (synthetic seawater was used here, which is a mixture of the following ions: KCl, 0.0093 M; NaCl, 0.42 M; Na2SO4, 0.029 M; CaCl2, 0.011 M and MgCl2, 0.056 M).

[0064] Example 1: Characteristic Analysis of the Functionalized MoS2 Film of the Present Invention

[0065] Functionalized MoS2 nanomonolayers of the present invention were fabricated according to the procedures described in "Materials and Methods." These nanolayers are referred to as MoS2-cyst, MoS2-prop, or MoS2-merc. Functionalization with 1-propanethiol was performed in an organic solution consisting of water and DMSO due to the hydrophobic alkyl chains. Following functionalization, the DMSO was completely removed. A membrane composed of stacked functionalized MoS2 nanomonolayers was then fabricated by vacuum filtration according to the procedures described in "Materials and Methods."

[0066] Transmission electron microscopy (TEM) images revealed a hexahedral diffraction pattern in the functionalized nanolayers, confirming their MoS2 lattice structure. Energy distribution X-ray spectroscopy (EDS) revealed uniform distribution of nitrogen and sulfur within the MoS2-cyst nanolayers. TEM images also revealed that the interlayer spacing of the stacked MoS2-cyst nanolayers increased to 11.3 angstroms, significantly different from the 6.2 angstroms observed in the unfunctionalized MoS2 nanolayers. The thickness of the stacked MoS2-cyst nanolayers was approximately 1,300 nanometers, indicating that the functionalized MoS2 nanolayers were stacked in an orderly fashion. By controlling the volume of the filtered solution, membranes with identically smooth surfaces but varying thicknesses (e.g., 200, 600, or 1,300 nanometers) could be prepared. Importantly, magnified SEM images of the three prepared membranes revealed no visible pores. According to AFM measurements, the surface roughness of the synthesized MoS2-cyst membrane, MoS2-merc membrane, and MoS2-prop membrane were 44.8 nm, 39.9 nm, and 45.8 nm, respectively, indicating that the surface roughness of the membranes functionalized with different sulfhydryl (SH) groups was roughly the same.

[0067] In this embodiment, various analytical techniques were used to confirm that the surface of the MoS nanolayer was indeed covalently modified with sulfur groups. STEM images of the bottom plane of the prototype MoS nanolayer revealed a hexahedral pattern of 2H-MoS. Sulfur vacancies (Vs) were clearly visible, both directly and by analyzing the image using intensity mode along a specific STEM region.

[0068] FT-IR spectroscopy was then used to confirm the changes in the various functional groups on the MoS2 film after functionalization. As expected, the pure MoS2 film did not show any vibration peaks, while pure cysteine, 3-mercaptopropane-1,2-diol, or 1-propanethiol showed peaks at 2550, 2556, and 2561 cm, respectively. -1 Frequency (V SH) exhibits a vibrational peak representing SH stretching. After functionalization, the SH stretching peak disappears, indicating that the SH ligands (cysteine, 3-mercaptopropane-1,2-diol, or 1-propanethiol) are dehydrogenated and that CS has been grafted onto the Vs position of the MoS2 nanolayer in the CS-Mo state. EPR spectroscopy also confirms the reduction in vacancies. The peak intensity at approximately 3510 gauss is expected to be proportional to the sulfur vacancy concentration. The original unfunctionalized MoS2 nanolayer exhibits a stronger signal, nearly two times higher than that of the MoS2-cyst, MoS2-prop, or MoS2-mere nanolayers. This result demonstrates that molecules such as cysteine, 3-mercaptopropane-1,2-diol, or 1-propanethiol have been successfully grafted onto the S vacancies in the exfoliated MoS2 nanolayer, effectively reducing vacancies.

[0069] XRD confirmed that the functionalization of Vs resulted in a larger interlayer spacing in the functionalized MoS2 film. The peak in the (002) plane of the prototype MoS2 film is located at approximately 14.2°, representing an interlayer spacing (d) of approximately 6.4 Å. This value is very close to that of bulk MoS2 powder (14.3°), confirming that the stacking of the prototype nanolayers is similar to that of bulk MoS2. The peak in the (002) plane of the MoS2-cyst, MoS2-merc, and MoS2-prop films shifts to lower positions of approximately 7.9°, 8.2°, and 7.8°, respectively, corresponding to interlayer spacings (d) of approximately 11.3 Å, 10.9 Å, and 11.4 Å, respectively. This trend indicates that the functional groups grafted onto the MoS2 film can regulate the interlayer spacing of the stacked MoS2 nanolayers, laying the foundation for applications in water desalination. The capillary channel width of the unfunctionalized MoS2 membrane is approximately 0.2 Å, while the capillary channel widths of the MoS2-cyst, MoS2-merc, and MoS2-prop membranes are approximately 5.1 Å, 4.7 Å, and 5.2 Å, respectively. These data were calculated using XRD, after deducting the interlayer spacing of approximately 6.2 Å for bulk MoS2.

[0070] In order to quantitatively analyze the covalent properties after functionalization, 13C cross-polarization magic angle spinning nuclear magnetic resonance (CPMAS NMR) is used to distinguish the chemical environment of the carbon in the functional group before and after functionalization. The chemical shift of the C-S bond can be used as an indicator of the chemical environment of the functional group. Using the liquid-state NMR of the prototype thiol reagent as a reference, the C-S bond chemical shifts of cysteine, 3-mercaptopropane-1,2-diol, and 1-propanethiol were measured at δ = 24.6 ppm, 26.5 ppm, and 77.4 ppm, respectively. After functionalization, the C-S bond chemical shifts on MoS2-cyst, MoS2-merc, or MoS2-prop films shift to 27.8 ppm, 34.5 ppm, and 112.5 ppm, respectively. The carbon chemical shift is due to the covalent bond between the sulfur atom (derived from the -SH group after dehydrogenation of the thiol) and the Mo atom at the S vacancy. In addition, based on the results of ab initio molecular dynamics (AIMD) simulations of the functionalized membranes in water, the average bond length of the SC bond and the average bond energy of the MoS2-cyst, MoS2-merc or MoS2-prop membranes were approximately 1.85±0.04 and 1.81±0.32 eV, respectively, reaffirming that the bonds on the functionalized MoS2 membranes are covalent.

[0071] in accordance with Figure 1 Data confirms that the surface wettability of functionalized MoS2 membranes (i.e., MoS2-cyst, MoS2-merc, or MoS2-prop) is approximately 64.8, 70.3, or 90 degrees, respectively. This compares to a contact angle of approximately 53.9 degrees for the unfunctionalized MoS2 membrane. This result demonstrates that different functional groups alter the surface chemistry of the membrane.

[0072] XPS spectroscopy was used to analyze the chemical composition of the functionalized MoS2 films. The composition of the successfully cysteine-functionalized MoS2 films was confirmed by monitoring the 1s spectra of nitrogen in the MoS2-cyst films, and the results were consistent with the EDS results. The 3d spectra of Mo (223-234 eV) showed minimal changes in the relevant components of the 1T and 2H phases between the original MoS2 films and the functionalized MoS2 films, indicating that the functionalization process did not alter the phase of the MoS2 nanolayer.

[0073] Deconvolution of the sulfur 2p spectrum (158-166 eV) reveals two sulfur 2p doublets in the original MoS2 film, consistent with the 1T and 2H phases of the functionalized MoS2 film. However, the functionalized MoS2 films (i.e., MoS2-cyst, MoS2-merc, or MoS2-prop) exhibit additional sulfur 2p doublets, indicating the presence of S-C bonds derived from these functional groups. The degree of functionalization was calculated based on the percentage of S-C bonds in the total S2p spectrum, yielding 14%, 10%, and 10% functionalization percentages for the MoS2-cyst, MoS2-merc, and MoS2-prop films, respectively. Comparison of the 1s XPS spectra of carbon atoms in the original and functionalized MoS2 films also confirms the functionalization with different sulfur-containing molecules. Sample calibration was performed using carbon located at 284.8 eV, which is present in both the original MoS2 film and the functionalized MoS2 film. Additional C=O (285-290 eV) and CX (285-288 eV) peaks were observed in the MoS2-cyst film, while an additional CX (284-288 eV) peak was observed in the MoS2-merc film, and an additional CX (285-289 eV) peak was observed in the MoS2-prop film.

[0074] The Raman spectra of the prototype MoS2 membrane and the functionalized MoS2 membranes (i.e., MoS2-cyst, MoS2-merc, and MoS2-prop membranes), as well as the Raman spectra of the functionalized MoS2 membranes after long-term FO filtration cycles, all show that the functionalization treatment or long-term filtration testing does not affect the structure or phase of the MoS2 membrane. 1 2g (378cm -1 ) and out-of-plane A 1g (406cm -1 ) has a high intensity. After functionalization, these E 1 2g and A 1g The peaks of E in the functionalized MoS2 membrane still exist even after 11 filtration cycles. 1 2g and A 1g The peak intensity remains unchanged. Furthermore, SEM images of the functionalized MoS2 membrane after filtration reveal that its layered structure remains intact, with no pores forming on the surface due to filtration. This intact appearance indicates that the functionalized MoS2 membrane is extremely stable in solution, demonstrating its antifouling properties.

[0075] The expansion of the membrane in aqueous solution is also an important indicator of stability. In this embodiment, the expansion of membranes made of various 2D materials is investigated. Figure 2 The results show that GO and MXene expanded by approximately 70% and 27%, respectively, making them unsuitable for continuous desalination filtration testing. In contrast, the functionalized MoS2 membranes of the present invention exhibited excellent results. After immersion in water for 24 hours, the MoS2-cyst, MoS2-merc, and MoS2-prop membranes expanded by 1.3%, 3.7%, and 0.6%, respectively. Because the functionalized groups are hydrophilic, the expansion percentages of the MoS2-cyst and MoS2-merc membranes were similar to that of the prototype MoS2 membrane (2%). The expansion percentage of the MoS2-prop membrane was lower than that of the prototype MoS2 membrane, likely due to the hydrophobic nature of the functionalized groups. Overall, the expansion of the functionalized MoS2 membranes was much lower than that of GO or MXene membranes. The data of this embodiment also supports the covalent bond between the MoS2 membrane and the sulfur groups, and this functionalization can also expand the spacing between the layers, thereby serving as an effective path for water permeation and having excellent anti-swelling properties.

[0076] Example 2: Effect of functionalized MoS2 membrane in removing ions in Example 1

[0077] In this example, the ion removal performance of prototype MoS membranes of varying thickness (200 nm, 600 nm, or 1300 nm) was compared with that of functionalized MoS membranes (i.e., MoS-cyst, MoS-merc, and MoS-prop membranes) in a customized filtration device. The filtration device consisted of two chambers, one for the feed solution and the other for the extraction solution. In this example, a 2 M sucrose solution was used as the extraction solution, and 0.5 M NaCl was used as the simulated seawater feed solution. The water flux of the prototype MoS membrane and the functionalized MoS membrane was measured.

[0078] The results showed that the prototype MoS2 membrane had no water flux, which was consistent with the results of previous reverse osmosis experiments. However, the MoS2 membrane functionalized with cysteine, 1-propanethiol, or 3-mercaptopropane-1,2-diol allowed water to permeate through it while effectively retaining ions. As the membrane thickness increased from 200 nm to 600 nm and finally to 1,300 nm, the water flux of the functionalized MoS2 membranes (i.e., MoS2-cyst, MoS2-merc, and MoS2-prop membranes) increased from 43.3, 35.7, and 54.1 mol / m 2 / h decreased to 30.2, 28.6, and 31.1 mol / m 2 / h, and finally to 19.6, 13.3, and 24.7 mol / m 2 / h. For the 200nm membrane, the water flux of MoS2-prop membrane is the highest, which is better than GO and MXene membranes. The water flux of the 600nm thick MoS2-prop membrane is as high as 2.626mol / m 2 / h / bar, surpassing the previously published data of MoS2 film (1.544 mol / m 2 / h / bar), GO / graphene membrane (0.372 mol / m 2 / h / bar), and MXene membrane (1.222 mol / m 2 / h / bar). The MoS2-cyst, MoS2-merc and MoS2-prop membranes of the present invention with a thickness of about 200 nanometers have an efficiency of 96.9%, 96% and 97.9% in removing sodium ions, respectively. When the membrane thickness increases to 600 nanometers, the efficiency of removing sodium ions reaches 99.1%, 99.1% and 99.3%, respectively. When the membrane thickness increases to 1,300 nanometers, the efficiency of removing sodium ions reaches 99.7%, 99.7% and 99.5%, respectively. Figure 3 ).

[0079] To evaluate the stability of the functionalized MoS2 membranes, the membranes (600 nm thick) were subjected to 11 filtration cycles, with feed and extract solutions added before each cycle. The results showed that the functionalized MoS2 membranes of the present invention (i.e., MoS2-cyst, MoS2-merc, and MoS2-prop membranes) all exhibited excellent stability ( Figure 4 ).

[0080] Furthermore, when the functionalized MoS2 membranes of the present invention (i.e., MoS2-cyst, MoS2-merc, or MoS2-prop membranes with a thickness of about 600 nm) were subjected to forward osmosis (FO) for 24 hours, all the membranes could effectively retain (>99%) various hydrated ions (including Na + , K + , Ca 2+ Mg 2+ )( Figure 5 ). In detail, when 0.5M NaCl was used as the feed solution, the MoS2-prop membrane retained Na + The effect is the highest, about 99.3% of sodium ions will be rejected. In addition, its salt retention effect will increase as the diameter of the salt hydrated ion increases from 6.6 angstroms (K + ) increased to 7.2 angstroms (Na + )、8.2 Angstroms (Ca 2+ ) to 8.6 angstroms (Mg2+ ), and from K + (99.2%) increased to Na + (99.3%), Ca 2+ (99.5%) to Mg 2+ (99.6%). MoS2-cyst and MoS2-merc membranes also showed a trend similar to the results of MoS2-prop membrane, indicating that the functionalized MoS2 membrane can effectively intercept multivalent ions and monovalent ions. Compared with the effect of membranes made of other 2D inorganic materials on ion interception, the functionalized MoS2 membrane of the present invention showed better ion removal and water flux than most GO or MXene membranes ( Figure 6 ).

[0081] In order to further confirm the ion permeation effect of the functionalized MoS2 membrane of the present invention, the membrane was allowed to filter continuously for 100 hours. The results are shown in FIG. Figure 7 middle. Na + The average permeability through the MoS2-prop membrane was 0.0106 mol / m 2 / h, which is significantly lower than that of MoS2-cyst membrane (0.0259 mol / m 2 / h) or MoS2-merc membrane (0.0239mol / m 2 / h), demonstrating that the MoS2-prop membrane's filtration performance far surpasses that of other membranes. The low ion permeability of the MoS2-prop membrane is likely due to steric hindrance, as the width of its capillary channels (5.2 angstroms) is smaller than the diameter of a typical hydrated ion (approximately 6.6-8.6 angstroms). Overall, the data from this embodiment demonstrates that the functionalized MoS2 membrane of the present invention can operate continuously for 100 hours with a stable flow rate.

[0082] The effect of the functionalized MoS2 membrane of the present invention was further tested using synthetic seawater for 100 hours. The synthetic seawater contained KCl (0.0093M), NaCl (0.42M), Na2SO4 (0.029M), CaCl2 (0.011M), and MgCl2 (0.056M). + The concentration of is the highest, so its permeability is also the highest. Figure 8 As shown, all ions (Na + , K + , Ca 2+ Mg 2+ )The permeation flux through the MoS2-prop membrane is lower than that through the MoS2-cyst membrane or the MoS2-merc membrane. This is because the capillary channels of the MoS2-prop membrane are the narrowest, resulting in the lowest cation permeability. Figure 9It shows that after 100 hours of continuous filtration, the MoS2-prop membrane (600 nm) maintains the retention of Na + The ratio is 97.3%, and the MoS2-cyst membrane and MoS2-merc membrane retain Na + The proportions are 96% and 96.4% respectively.

[0083] The functionalized MoS2 membranes were also tested for their chloride tolerance. Chloride is a chemical often used to reduce biofouling. The membranes were repeatedly exposed to a dilute sodium hypochlorite solution (200 ppm). After six cycles, the MoS2-prop membrane (600 nm) exhibited the highest sodium ion retention (90%), comparable to the results of commercially available CTA polymer membranes (data not shown). Furthermore, XRD spectroscopy revealed no shift in the diffraction peak at 7.8° after sodium hypochlorite treatment (compared to the prototype MoS2 membrane), demonstrating the MoS2-prop membrane's strong chloride resistance.

[0084] Since the function of membrane to remove ions is limited by permeability and selectivity, the effect of forward osmosis membrane to remove ions can be evaluated by the relationship between water-salt permeability-selectivity and water permeability constant. 1 ) can be determined by the water permeability (mol / m 2 / h / bar) divided by the salt flux (mol / m 2 The water-salt permeability-selectivity of the MoS2-prop membrane reached 800 bar⁻¹, significantly higher than that of the MoS2-cyst membrane (554 bar⁻¹) and the MoS2-merc membrane (511 bar⁻¹), and also higher than that of GO or MXene membranes (data not shown). This result demonstrates the excellent performance of the functionalized MoS2 membranes of the present invention.

[0085] In order to measure the interlayer spacing of MoS2-cyst, MoS2-merc and MoS2-prop films, the above films were immersed in deionized water or 0.5M saline (KCl, NaCl, Na2SO4, CaCl2 and MgCl2) for about 24 hours and their XRD spectra were measured. For example, in NaCl solution, the (002) peaks of MoS2-cyst, MoS2-merc and MoS2-prop films are located at 7.4°, 7.6° and 7.8°, respectively, and correspond to capillary channel widths of approximately 5.7 Å, 5.4 and 5.2 Å, respectively. In contrast, the capillary channel widths of the prototype MoS2 film are approximately 5.1 Å, 4.7 and 5.2 Å, see Figure 10aFor the MoS2-cyst membrane, when immersed in deionized water or 0.5M saline, the capillary channel width increases to 5.4 and 5.7 angstroms, respectively. 2+ and Mg 2+ The capillary channel width of the membrane in salt water ( Figure 10a ) and long-term salt retention performance ( Figures 10b-10c ) were correlated and found that the smaller the capillary channel width of the membrane in salt water, the better its salt retention effect. For example, the MoS2-prop membrane can retain 97.3% of sodium ions, and its capillary channel width in NaCl solution is the smallest (5.2 angstroms); the MoS2-cyst membrane can only retain 96% of sodium ions, and its capillary channel width in NaCl solution is the largest (5.7 angstroms). As for the MoS2-merc membrane, the effect is in between (96.4%, 5.4 angstroms). However, it is difficult to distinguish between MoS2-cyst and MoS2-merc membranes in calcium and magnesium ion solutions because their capillary channel widths are similar ( Figures 10d-10e This result shows that the ion flow is limited by the width of the capillary channel, and also shows the strong nanochannel effect in the functionalized MoS2 membrane of the present invention.

[0086] In order to further find out the reason why the MoS2-prop membrane has a high water flux, the structure of the functionalized MoS2 membrane of the present invention was analyzed from the full width at half maximum (FWHM) of the (002) peak of the XRD spectrum. The results are shown in Figure 10f The FWHM of the diffraction peak can be considered as a factor that can be used to qualitatively evaluate the disorder of 2D nanolayer stacking. Figure 10f The FWHM of the MoS2-prop membrane in NaCl solution is 1.8 Å, which is larger than that of the MoS2-cyst (1.13 Å) and MoS2-mere membrane (1.12 Å) in the same solution. Therefore, the water flux of the MoS2-prop membrane using NaCl solution (54.1 mol / m 2 / h) will be higher than MoS2-cyst (43.3mol / m 2 / h) and MoS2-mere film (35.7 mol / m 2 This may be because its disordered structure causes the stacking order of the nanolayers to change, which in turn shortens the effective path length for water molecules to be transported between membrane layers, thereby improving water permeation.

[0087] The effectiveness of the functionalized MoS2 membranes of the present invention in retaining dyes was also evaluated. Using a UV-Vis spectrometer and the Lambert-Beer law, the effectiveness of the functionalized MoS2 membranes of the present invention was evaluated before and after dye injection. Three dyes, rhodamine B, methyl blue, and methyl orange, were selected and tested in an FO module. All functionalized MoS2 membranes (MoS2-cyst, MoS2-merc, and MoS2-prop membranes, 600 nanometers thick) retained more than 90% of the dye. Comparing the molecular weight of the target dye molecule with the retention rate revealed that the retention rate increased with increasing molecular weight. In other words, the greater the molecular weight, the better the rejection, indicating that molecular weight is crucial for screening. The MoS2-prop membrane has the narrowest capillary channel width and, therefore, the best dye rejection. These results indicate that the primary factor in the ability of the functionalized MoS2 membranes of the present invention to screen molecules or ions is the spacing between the layers, which is consistent with results previously reported in the literature.

[0088] The present invention utilizes the sulfur atom vacancies generated by the exfoliated MoS2 nanolayer to functionalize the MoS2 nanolayer with three different SH group-containing compounds: cysteine, 1-propanethiol, or 3-mercaptopropane-1,2-diol. As a result, the capillary channel width of the prototype MoS2 membrane can be adjusted from 0.2 angstroms to 5.2 angstroms of the MoS2-prop membrane, allowing water to pass through the membrane during forward osmosis. Compared to the MoS2-cyst membrane (43.3 mol / m 2 / h) and MoS2-merc membrane (35.7 mol / m 2 / h), MoS2-prop membrane showed the highest water flux (54.1 mol / m 2 / h), which is due to the reaction between water and the hydrophobic groups on the MoS2-prop membrane. In addition, in NaCl solution, the capillary channel width of the MoS2-prop membrane is about 5.2 angstroms, so it can show the highest retention of Na + The effect was 97.3%, compared with the MoS2-cyst membrane with a capillary channel width of about 5.7 Egypt and a retention rate of 96% and the MoS2-merc membrane with a capillary channel width of about 5.4 Egypt and a retention rate of 96.4%.

[0089] In summary, the present invention has developed a method for covalently grafting sulfur groups onto sulfur atom vacancies in MoS2 membranes, thereby achieving the effect of controlling the interlayer spacing of MoS2 membranes. Systematic studies have shown that after the MoS2 membrane is modified with hydrophobic groups (e.g., propanethiol), it exhibits a higher screening effect for micropollutants and salts, even in synthetic seawater (with a salt retention rate of up to 99.3% and a water / salt selectivity of approximately 800 bar). -1). The experimental results highlight the positive effect of hydrophobic functional groups on improving the water flux of MoS2 membranes. It is known that the width of the capillary channel plays a key role in the retention of salts and micropollutants in wastewater. Overall, the strategy of functionalizing MoS2 membranes in this invention provides a promising development direction for next-generation wastewater purification membranes.

[0090] Although the above embodiments disclose specific embodiments of the present invention, they are not intended to limit the present invention. Those skilled in the art may make various changes and modifications without departing from the principles and spirit of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined by the accompanying patent applications.

Claims

1. A film formed by stacking nano-monolayers of transition metal dichalcogenides (TMDs) functionalized with sulfur groups, wherein: The TMD nanomonolayer functionalized with thiol groups is formed by reacting a TMD nanomonolayer dispersion with a sulfur-containing compound, wherein the sulfur-containing compound is cysteine, 1-propanethiol, or 3-mercaptopropane-1,2-diol; and The membrane is characterized by a water-permeable capillary channel network, each capillary channel having a width of about 4.5-5.5 angstroms, a surface wettability contact angle of about 64-90 degrees, a functionalization degree of about 10-15%, a swelling degree of about 0.5-4.0%, and a thickness of about 200-1,300 nanometers.

2. The membrane according to claim 1, wherein the TMD nano-monolayer dispersion is prepared by the following steps: (i) discharging the TMD bulk material in a lithium battery to produce a lithiated TMD bulk material; (ii) ultrasonically vibrating the lithiated TMD bulk material in water to exfoliate the lithiated TMD bulk material into a TMD nano-monolayer; (iii) collecting the product of step (ii) by centrifugation; and (iv) redispersing the product of step (iii) in water to form the TMD nanomonolayer dispersion.

3. The film of claim 2, wherein the TMD nanomonolayer is a MoS2 nanomonolayer.

4. The membrane according to claim 3, wherein The sulfur-containing compound is 1-propanethiol; and The width of each capillary channel in the water-permeable capillary channel network of the membrane is about 5.2 angstroms, the contact angle of the surface wettability is about 90 degrees, the functionalization degree is about 10%, and the swelling degree is about 0.6%.

5. The membrane according to claim 3, wherein The sulfur-containing compound is cysteine; and The width of each capillary channel in the water-permeable capillary channel network of the membrane is about 5.1 angstroms, the contact angle of the surface wettability is about 65 degrees, the degree of functionalization is about 14%, and the degree of swelling is about 1.3%.

6. The membrane according to claim 3, wherein The sulfur-containing compound is 3-mercaptopropane-1,2-diol; and The width of each capillary channel in the water-permeable capillary channel network of the membrane is about 4.7 angstroms, the contact angle of the surface wettability is about 70 degrees, the functionalization degree is about 10%, and the swelling degree is about 3.7%.

7. A method for removing ions from a fluid, comprising passing the fluid through the membrane of claim 1 by forward osmosis for at least 24 hours.

8. The method of claim 7, wherein the TMD nanomonolayer is a MoS2 nanomonolayer.

9. The method according to claim 8, wherein The sulfur-containing compound is 1-propanethiol; and The width of each capillary channel in the water-permeable capillary channel network of the membrane is about 5.2 angstroms, the contact angle of the surface wettability is about 90 degrees, the functionalization degree is about 10%, and the swelling degree is about 0.6%.

10. The method according to claim 8, wherein The sulfur-containing compound is cysteine; and The width of each capillary channel in the water-permeable capillary channel network of the membrane is about 5.1 angstroms, the contact angle of the surface wettability is about 65 degrees, the degree of functionalization is about 14%, and the degree of swelling is about 1.3%.

11. The method according to claim 8, wherein The sulfur-containing compound is 3-mercaptopropane-1,2-diol; and The width of each capillary channel in the water-permeable capillary channel network of the membrane is about 4.7 angstroms, the contact angle of the surface wettability is about 70 degrees, the functionalization degree is about 10%, and the swelling degree is about 3.7%.

12. The method of claim 7, wherein the fluid comprises ions selected from the group consisting of sodium ions, potassium ions, magnesium ions, calcium ions, and combinations thereof.

13. The method of claim 12, wherein the membrane removes at least 90% of the ions in the fluid.

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