A high-flux oil-water separation device, an oil-water separation method and application

Abstract

The application relates to the field of oil-water separation equipment, in particular to a high-flux oil-water separation device, an oil-water separation method and application. The oil-water separation device comprises a liquid inlet cavity, a liquid inlet is arranged on the liquid inlet cavity, one end of the liquid inlet cavity is provided with an ultralayered polypropylene fiber membrane, and the other end is provided with an oleophilic fiber membrane; the oil-water separation device further comprises a water outlet and an oil outlet, the water outlet is communicated with the liquid inlet cavity through the ultralayered polypropylene fiber membrane, and the oil outlet is communicated with the liquid inlet cavity through the oleophilic fiber membrane; the static contact angle between the ultralayered polypropylene fiber membrane and water can reach 0 within 1 second. The oil-water separation device realizes efficient separation of oil and water, and widens the application range of the membrane material for realizing efficient oil-water separation. The oil-water separation device is simple, has high water and oil flux, and has extremely high application value.

Description

Technical Field

[0001] This invention relates to the field of oil-water separation equipment, specifically to a high-throughput oil-water separation device, oil-water separation method, and application. Background Technology

[0002] With rapid industrial development, environmental pollution has become increasingly severe. Water pollution is the most common environmental problem. Oily wastewater pollution is particularly prevalent among water pollutants. Oily wastewater is discharged in many fields, including crude oil extraction, textiles, and metallurgy, causing serious pollution to water resources. Therefore, the treatment of oily wastewater is of paramount importance.

[0003] Based on their principles, separation methods can be categorized into physical methods, physicochemical methods, chemical methods, and biological methods. Physical methods can be further divided into gravity methods, centrifugation methods, and membrane separation methods. Membrane separation methods, characterized by low energy consumption and ease of operation, have experienced rapid development in recent years. Membrane separation methods can also be divided into negative pressure driven methods and gravity driven methods. Negative pressure driven methods require applying a pressure difference across the membrane to achieve separation, while gravity driven methods achieve separation of water and other substances under the influence of gravity. The membrane material is a crucial factor affecting the separation effect and efficiency.

[0004] Current membrane materials can be categorized into hydrophobic / oleophilic membranes and hydrophilic / oleophobic membranes, but existing technologies suffer from insufficient flux, failing to achieve efficient oil-water separation. Furthermore, the high cost of current membrane materials cannot meet the rapidly growing demands of wastewater treatment. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a high-efficiency oil-water separation device and method. The device uses a superspreadable polypropylene fiber membrane material with water superspreading properties as the water separation membrane, and also has excellent water treatment flux, enabling the treatment of large quantities of oily wastewater. It is characterized by high efficiency and ease of operation.

[0006] The first aspect of the present invention is to provide an oil-water separation device, including a liquid inlet chamber, wherein a liquid inlet is provided on the liquid inlet chamber, a super-spreadable polypropylene fiber membrane is provided at one end of the liquid inlet chamber, and an oleophilic fiber membrane is provided at the other end.

[0007] The oil-water separation device further includes a water outlet and an oil outlet. The water outlet is connected to the liquid inlet chamber through the ultra-spreadable polypropylene fiber membrane, and the oil outlet is connected to the liquid inlet chamber through the oleophilic fiber membrane.

[0008] The super-spreadable polypropylene fiber membrane comprises a polypropylene fiber membrane matrix and an amphiphilic polymer. Based on the mass of the super-spreadable polypropylene fiber membrane as 100%, the content of the polypropylene fiber membrane matrix in the super-spreadable polypropylene fiber membrane is 93%-99.99%; the content of the amphiphilic polymer is 0.01%-7%; and the static contact angle between the super-spreadable polypropylene fiber membrane and water can reach 0° within 1 second.

[0009] In this invention, the super-spreadable polypropylene fiber membrane is a superhydrophilic polypropylene fiber membrane without a layered structure.

[0010] Superspreading (also known as superdiffusion or superwetting) is a common term in this field. For example, the paper "Superspreading Phenomenon and Essence of Silicon Surfactants" in the 8th issue of *Daily Chemicals Science* (2019) and the paper "Research Progress on the Superspreading Characteristics of Fluids on Solid Surfaces" in the 3rd issue of Volume 65 of *Journal of Chemical Industry and Engineering* (March 2014) both describe superspreading. Generally, it refers to the ability of small-volume droplets (below 2 μl, excluding the influence of gravity) to quickly achieve a contact angle of 0° upon contact with an object's surface. For instance, the superspreading polypropylene fiber membrane of this invention achieves a static contact angle of 0° for water within no more than 1 second, preferably within 0.005 seconds to 1 second. Materials with superspreading properties have better hydrophilicity than traditional superhydrophilic materials (contact angle less than 5°), allowing liquids to rapidly transfer and flow within the material, resulting in high throughput and significant advantages in separation, filtration, and other fields. The superspreading polypropylene fiber membrane of this invention refers to a water-superspreading polypropylene fiber membrane.

[0011] According to the present invention, the super-spreadable polypropylene fiber membrane comprises a polypropylene fiber membrane matrix and an amphiphilic polymer. Based on the mass of the super-spreadable polypropylene fiber membrane, the content of the polypropylene fiber membrane matrix in the super-spreadable polypropylene fiber membrane is 93%-99.99%; the content of the amphiphilic polymer is 0.01%-7%; and the static contact angle between the polypropylene fiber membrane and water can reach 0° within no more than 1 second. In a preferred embodiment of the present invention, based on the mass of the super-spreadable polypropylene fiber membrane, the content of the polypropylene fiber membrane matrix in the super-spreadable polypropylene fiber membrane is 95%-99.95%, for example, 95%, 97%, 98.3%, 99%, 99.95%, or any two values ​​or any range of any two values; the content of the amphiphilic polymer is 0.05%-5%, for example, 0.01%, 0.7%, 3%, 5%, or any two values ​​or any range of any two values.

[0012] Preferably, the sum of the content of the polypropylene fiber membrane matrix and the content of the amphiphilic polymer is 100%.

[0013] According to the present invention, the mass content of the amphiphilic polymer in the super-spreadable polypropylene fiber membrane can be detected using conventional testing methods in the art. These methods include, but are not limited to, the following: weigh an unmodified polypropylene nonwoven fabric (m1), treat it using the methods listed in the examples, and then dry it to obtain a treated polypropylene fiber membrane (m2). The mass content of the amphiphilic polymer is calculated as (m2-m1) / m2 × 100%.

[0014] According to the present invention, the selectable range of amphiphilic polymer content per unit surface area of ​​the super-spreadable polypropylene fiber membrane is relatively wide. In a preferred embodiment of the present invention, the amphiphilic polymer content per unit surface area of ​​the super-spreadable polypropylene fiber membrane is 0.005 g / m². 2 -3g / m 2 The preferred value is 0.005 g / m 2 -2g / m 2 For example, 0.005g / m 2 1g / m 2 2g / m 2 , and any two values ​​or any interval of any two values.

[0015] According to the present invention, the content of amphiphilic polymer per unit surface area of ​​the super-spreadable polypropylene fiber membrane can be detected using conventional detection methods in the art. These methods include, but are not limited to, the following: First, the sample to be tested is coated with gold on its surface. Then, the coated sample is placed on an SEM detection stage, and a 5μm × 5μm area on the sample is scanned using SEM. Then, the mass fraction of oxygen in this area is determined using EDS energy dispersive spectroscopy for the unmodified polypropylene fiber membrane and the hydrophilically modified polypropylene fiber membrane, denoted as w0 and w1 respectively. The oxygen content is then calculated using the following formula: W = (w1 - w0) / (M O / M A )×M, where M O M is the relative atomic mass of oxygen. A M is the molecular weight of a single unit of the amphiphilic polymer, M is the areal density of the polypropylene fiber membrane, and W is the content of the amphiphilic polymer per unit area of ​​the super-spreadable polypropylene fiber membrane.

[0016] According to the present invention, the polypropylene fiber membrane matrix can be selected from a wide range of options. For example, the fiber membrane matrix can be meltblown polypropylene nonwoven fabric, spunbond polypropylene nonwoven fabric, or a multilayer composite fabric of meltblown polypropylene nonwoven fabric and spunbond polypropylene nonwoven fabric.

[0017] According to the present invention, when the fiber diameter of the fiber membrane is within a certain range, capillary forces can be generated between the fibers, thereby improving the hydrophilicity of the polypropylene fibers through self-assembled amphiphilic polymers, allowing water to spread at an extremely rapid speed under the action of capillary forces. In a preferred embodiment of the present invention, the fiber diameter in the superspreadable polypropylene fiber membrane is less than 20 micrometers, preferably less than 10 micrometers, and more preferably 0.1-10 micrometers.

[0018] The fiber diameter range of the polypropylene fiber membrane matrix described in this invention refers to the nominal fiber diameter range or statistically obtained value of commercially available polypropylene fiber membrane matrices in the art. Where the nominal fiber diameter range or statistically obtained value is within the scope of this invention, even if some (or a few) fibers in the overall polypropylene fiber membrane matrix have diameter ranges outside the scope of this invention, they are still within the protection scope of this invention.

[0019] The above methods for detecting fiber diameter can employ conventional testing techniques in this field, including but not limited to observing fibers under microscopes such as electron microscopes and optical microscopes, and measuring and statistically analyzing the fiber diameter.

[0020] According to the present invention, only amphiphilic and water-soluble polymers can achieve capillary self-assembly. In a preferred embodiment of the present invention, the amphiphilic polymer is selected from polyvinyl alcohol. The present invention achieves the coating of amphiphilic polymers on the surface of polypropylene fibers through capillary self-assembly, thereby achieving superhydrophilic and superspreading effects. Experimental verification has shown that non-amphiphilic polymers cannot improve polypropylene fiber membranes.

[0021] According to the present invention, the water-soluble amphiphilic copolymer refers to a polymer whose molecular chain contains both hydrophilic and lipophilic segments. Such polymers exhibit a certain affinity for two phases with different properties (usually an aqueous phase and an oil phase). Preferably, the amphiphilic polymer is polyvinyl alcohol and / or a crosslinked polymer formed from polyvinyl alcohol and a crosslinking agent; more preferably, it is a crosslinked polymer formed from polyvinyl alcohol and a crosslinking agent.

[0022] According to the present invention, in order to ensure the long-term and efficient operation of the separation device, the amphiphilic polymer undergoes a cross-linking reaction. The range of cross-linking agents is relatively wide. In a preferred embodiment of the present invention, the cross-linking agent is selected from at least one of polybasic acids and polybasic aldehydes, including but not limited to at least one of glutaraldehyde and boric acid.

[0023] According to the present invention, the crosslinking agent is preferably selected from at least one of polybasic acids and polybasic aldehydes, more preferably glutaraldehyde and / or boric acid.

[0024] According to the present invention, the super-spreadable polypropylene fiber membrane is a superhydrophilic polypropylene fiber membrane without a layered structure.

[0025] The layered structure refers to the layering of the modified fiber membrane (or fiber cloth). Taking an amphiphilic polymer-modified fiber membrane as an example, a layered amphiphilic polymer layer is formed on the surface of the fiber membrane substrate, with the fiber membrane substrate lining one side of the amphiphilic polymer layer. Existing technologies mainly involve modified fiber membranes with layered structures, forming functional material layers (e.g., polymer layers or inorganic layers) on one or both sides of the membrane substrate. These functional material layers are macroscopically independent layered structures from the membrane substrate. The small amount of functional material penetrating into the membrane substrate has negligible weight and thickness compared to the functional material in the functional material layer, unlike the non-layered polymer in this invention.

[0026] The super-spreadable polypropylene fiber membrane of the present invention is a super-hydrophilic polypropylene fiber membrane without a layered structure. The amphiphilic polymer in the present invention does not have the above-mentioned layering. Instead, the amphiphilic polymer is wrapped around the outside of each fiber of the polypropylene fiber membrane.

[0027] According to the present invention, preferably, the amphiphilic polymer can self-assemble on the surface of the polypropylene fiber membrane matrix, with the oleophilic segments of the amphiphilic polymer assembling on the surface of the polypropylene fibers and the hydrophilic segments distributed on the fiber surface after assembly, thereby improving the hydrophilicity of the polypropylene fiber membrane. Preferably, the superspreadable polypropylene fiber membrane contains polypropylene fibers coated with the amphiphilic polymer, which can be observed under a transmission electron microscope after staining with ruthenium.

[0028] In a preferred embodiment of the present invention, the superspreadable polypropylene fiber membrane contains polypropylene fibers coated with an amphiphilic polymer. Preferably, the amphiphilic polymer is coated onto the polypropylene fibers through capillary self-assembly. That is, self-assembly is achieved under the action of capillary force, with the oleophilic segments of the water-soluble amphiphilic polymer adhering to the surface of the polypropylene fibers, while the hydrophilic segments are exposed, thereby forming a fiber surface with a hydrophilic structure. In application, the capillary structure of the fiber membrane itself is well preserved, and with the effect of the amphiphilic polymer, a hydrophilic / superspreadable effect is achieved under the action of capillary force. The amphiphilic polymer on the superspreadable polypropylene fiber membrane of the present invention differs from amphiphilic polymers cast or coated on the surface of the fiber membrane. The hydrophilicity distribution of the amphiphilic polymer in the present invention is more uniform, and the superspreadable polypropylene fiber membrane of the present invention does not have an obvious layered structure.

[0029] In a preferred embodiment of the present invention, the method for preparing the super-spreadable polypropylene fiber membrane includes:

[0030] The method involves contacting a polypropylene fiber membrane matrix with a solution containing an amphiphilic polymer under external force, wherein the content of the amphiphilic polymer in the solution is not higher than 5 wt%. Optionally, the polypropylene fiber membrane obtained after contacting the polypropylene fiber membrane matrix with the amphiphilic polymer is subjected to a crosslinking reaction in a solution containing a crosslinking agent to obtain the super-spreadable polypropylene fiber membrane.

[0031] As described above, the water-soluble amphiphilic polymer achieves self-assembly under capillary action. The lipophilic segments of the water-soluble amphiphilic polymer adhere to the surface of the polypropylene fiber, while the hydrophilic segments are exposed, thereby forming a fiber surface with a hydrophilic structure (i.e., the amphiphilic polymer is wrapped around the fiber surface), achieving a hydrophilic / superspreading effect under capillary action. The amphiphilic polymer in this invention has a more uniform distribution and does not have a layered structure.

[0032] Preferably, the contact is carried out in a solution containing an amphiphilic polymer.

[0033] The contact process utilizes intermolecular forces to enable the amphiphilic polymer to self-assemble on the surface of the polypropylene fiber membrane, resulting in a polypropylene fiber membrane coated with the amphiphilic polymer. Specifically, the water-soluble amphiphilic polymer (hydrophilic, oleophilic, and soluble in water) used in this invention allows the water-soluble polymer molecular chains to be dispersed in water and loaded onto the surface of the polypropylene fibers through self-assembly, thereby forming a fiber membrane with superhydrophilic properties. The superspreadable polypropylene fiber membrane achieves hydrophilic modification of the polypropylene fiber membrane by the amphiphilic polymer through capillary self-assembly.

[0034] This invention, through experiments, reveals that, through external force induction, water-soluble polymers with both hydrophilic and oleophilic segments can be self-assembled with polypropylene fiber membranes. Since polypropylene is an oleophilic polymer, the oleophilic segments of the water-soluble polymer assemble onto the fiber surface of the polypropylene fiber membrane. The hydrophilic segments, however, have weaker interactions with the polypropylene fibers and cannot assemble onto the fiber surface, thus remaining exposed. This process endows the polypropylene fibers with hydrophilic properties, and consequently, the polypropylene fiber membrane possesses both hydrophilic and oleophilic properties, with a rapid spreading time. Meanwhile, the fiber diameter in the polypropylene fiber membrane of the present invention is preferably less than 20 micrometers, preferably less than 10 micrometers, and more preferably 0.1-10 micrometers, which can generate strong capillary action. Water can be rapidly transferred along the fiber under the action of capillary force, thereby giving the polypropylene fiber membrane excellent spreading performance. The maximum size of the spreading area after the 2μL droplet is spread in the fiber membrane is not less than 7mm, the maximum size of the spreading area after the 5μL droplet is spread in the fiber membrane is not less than 8mm, the maximum size of the spreading area after the 8μL droplet is spread in the fiber membrane is not less than 12mm, and the maximum size of the spreading area after the 12μL droplet is spread in the fiber membrane is not less than 15mm.

[0035] In a preferred embodiment of the present invention, the content of the amphiphilic polymer in the solution is 0.05-4.5 wt%, preferably 0.1-4.5 wt%. Under the above-mentioned amphiphilic polymer concentration conditions and the action of external force, the contact utilizes intermolecular forces to cause the amphiphilic polymer to self-assemble on the surface of the polypropylene fiber membrane, thereby obtaining a polypropylene fiber membrane coated with the amphiphilic polymer.

[0036] As described above, the content of the amphiphilic polymer in the solution containing the amphiphilic polymer is 0.05-4.5 wt%, preferably 0.1-4.5 wt%, for example 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, and any two values ​​or any range of any two values, more preferably 0.3-3 wt%.

[0037] In a more preferred embodiment of the present invention, the contact is carried out in a solution containing an amphiphilic polymer, thereby resulting in a more uniform superspreading property of the obtained polypropylene fiber membrane.

[0038] According to the present invention, the contact between the fiber membrane and the amphiphilic polymer can be carried out over a wide temperature range, preferably not exceeding the melting temperature of polypropylene and the amphiphilic polymer, and more preferably not exceeding the glass transition temperature of the amphiphilic polymer.

[0039] In a preferred embodiment of the present invention, the preparation method further includes a step of drying the polypropylene fiber membrane matrix after it comes into contact with the amphiphilic polymer; preferably, the contact temperature and the drying temperature do not exceed the melting temperature of the fiber membrane matrix and the amphiphilic polymer, more preferably they do not exceed the glass transition temperature of the amphiphilic polymer.

[0040] According to the present invention, preferably, the contact is carried out under the action of external force; during the self-assembly of the amphiphilic polymer on the surface of polypropylene fiber, external force can be used to induce it to quickly achieve assembly, and the external force includes, but is not limited to, one or more of the following methods: ultrasound, rolling, filtration, lamination, molding, etc.

[0041] According to the present invention, the conditions for the application of external force are wide-ranging, such as the processing time, the number of processing times, and the process conditions of the processing method, without specific limitations.

[0042] Preferably, the external force is applied in a manner that includes one or more of the following: ultrasonication, rolling, filtration, lamination, and molding; more preferably,

[0043] The conditions for ultrasound include: the frequency of the ultrasound is not less than 5 kHz, preferably not less than 10 kHz, such as 10 kHz, 20 kHz, 30 kHz, 40 kHz, 45 kHz, 50 kHz, 55 kHz, and 60 kHz. The higher the ultrasonic power, the fewer the intervals and number of treatments.

[0044] According to the present invention, the ultrasonic processing equipment can be selected from conventional ultrasonic processing equipment, including but not limited to ultrasonic cleaning tables, cell disruptors, ultrasonic probes, industrial ultrasonic devices, etc. The present invention does not particularly limit the power of the specific ultrasonic processing equipment; preferably, the power is 50-750W, more preferably 50-500W, and even more preferably 150-350W.

[0045] According to the present invention, the ultrasonic treatment time in the preparation step can be selected within a wide range. The ultrasonic time is related to the solution concentration, fiber diameter, and areal density. According to the process conditions of the embodiments of the present invention, preferably, the ultrasonic time is not less than 1 minute, more preferably not less than 5 minutes, and more preferably 10-120 minutes, for example, it can be 10 minutes, 20 minutes, 30 minutes, 40 minutes, 60 minutes, 100 minutes, 120 minutes, etc.

[0046] In another preferred embodiment of the present invention, the filtration conditions can be selected over a wide range, and the processing time and number of processes can be reduced as the vacuum level increases. In a preferred embodiment of the present invention, the filtration conditions include: a vacuum level of not less than 5 Pa, preferably not less than 10 Pa, and / or a filtration time of not less than 1 second, preferably not less than 5 seconds. Preferably, the amphiphilic polymer solution remains wetted in the polypropylene fiber membrane matrix until filtration is stopped.

[0047] In another preferred embodiment of the present invention, the conditions for roller pressing include: pressure not less than 5 Pa, preferably not less than 10 Pa; and roller pressing times not less than 1 time.

[0048] In a more preferred embodiment of the present invention, the preparation method may include the following steps:

[0049] The polypropylene fiber membrane matrix is ​​brought into contact with a solution containing an amphiphilic polymer under external force; an aqueous solution of the amphiphilic polymer is then immersed in the polypropylene fiber membrane matrix; and the membrane is then dried.

[0050] As described above, in a preferred embodiment of the present invention, the amphiphilic polymer is selected from polyvinyl alcohol. That is, self-assembly is achieved under capillary action, with the lipophilic segments of the water-soluble amphiphilic polymer adhering to the surface of the polypropylene fiber, while the hydrophilic segments are exposed, thereby forming a fiber surface with a hydrophilic structure. In application, the capillary structure of the fiber membrane itself is well preserved, and with the added effect of the amphiphilic polymer, a hydrophilic / superspreading effect is achieved under capillary action.

[0051] The amphiphilic polymer on the superspreadable polypropylene fiber membrane of this invention differs from amphiphilic polymers cast or coated onto the surface of the fiber membrane. The amphiphilic polymer of this invention exhibits a more uniform hydrophilic distribution, and the superspreadable polypropylene fiber membrane of this invention does not have a significant layered structure. Furthermore, the amphiphilic polymer of this invention coats the surface of the fibers, rather than being cast or coated onto one side of the fiber membrane. This ensures excellent retention of capillary action between the fibers in this invention. Combined with the effect of the amphiphilic polymer, this allows water to achieve a hydrophilic / superspreading effect under capillary force during application.

[0052] According to the present invention, there are no particular limitations on the molecular weight of the amphiphilic polymer; for example, the number average molecular weight can be 30,000-300,000. Taking the embodiments described later as examples, polyvinyl alcohol with a degree of polymerization of 1700 can be selected.

[0053] According to the present invention, the polypropylene fiber membrane matrix can be selected from a wide range of materials, such as meltblown polypropylene nonwoven fabric, spunbond polypropylene nonwoven fabric, meltblown and spunbond polypropylene composite nonwoven fabric, spunlace polypropylene nonwoven fabric, etc. According to the present invention, meltblown polypropylene nonwoven fabric and meltblown and spunbond polypropylene composite nonwoven fabric are preferred.

[0054] According to the present invention, preferably, the areal density of the polypropylene fiber membrane matrix is ​​10-60 g / m³. 2 Preferably 20-50g / m 2 And / or, the fiber diameter is not greater than 20 micrometers, preferably less than 10 micrometers, and more preferably 0.1-10 micrometers. In this preferred embodiment, the fiber diameter of the fiber membrane generates capillary forces between the fibers, thereby improving the hydrophilicity of the polypropylene fibers through self-assembled amphiphilic polymers. Upon contact with water, water can spread out at an extremely rapid speed under the action of capillary forces.

[0055] The fiber diameter range of the polypropylene fiber membrane matrix described in this invention refers to the nominal fiber diameter range or statistically obtained value of commercially available polypropylene fiber membrane matrices in the art. Where the nominal fiber diameter range or statistically obtained value is within the scope of this invention, even if some (or a few) fibers in the overall polypropylene fiber membrane matrix have diameter ranges outside the scope of this invention, they are still within the protection scope of this invention. The fiber diameter detection method can employ conventional methods in the art, including but not limited to observing the fibers under a microscope, such as an electron microscope or an optical microscope, and measuring and statistically analyzing the fiber diameter.

[0056] The preparation method further includes an optional crosslinking step, which can be optionally performed according to the specific application, and preferably includes a crosslinking step.

[0057] In the crosslinking step, the polypropylene fiber membrane obtained by contacting the polypropylene fiber membrane matrix with the amphiphilic polymer is crosslinked in a solution containing a crosslinking agent.

[0058] The cross-linked amphiphilic polymers form a cross-linked structure, which increases the stability of the amphiphilic polymers in the fiber membrane and enhances the hydrophilic stability.

[0059] The aforementioned superspreading stability refers to the change in contact angle after the hydrophilic fiber membrane is completely immersed in deionized water and treated under ultrasonic cleaning conditions for 5 minutes, repeated 3 times. The smaller the change in contact angle, the better its hydrophilic stability.

[0060] According to the present invention, the crosslinking agent can be selected from a wide range. In a preferred embodiment of the present invention, the crosslinking agent is selected from at least one of polybasic acids and polybasic aldehydes, preferably at least one of glutaraldehyde and boric acid, and more preferably glutaraldehyde; and / or,

[0061] The crosslinking agent content in the solution is 0.005-0.8 wt%, preferably 0.01-0.5 wt%; and / or, the crosslinking temperature conditions include:

[0062] The crosslinking temperature does not exceed the glass transition temperature of the amphiphilic polymer, preferably 30-70°C; and / or the pH of the solution containing the crosslinking agent is 4-7; the crosslinking reaction time is 1 min-120 min, preferably 1 min-90 min, for example, it can be 1 min, 3 min, 5 min, 10 min, 20 min, 50 min, 70 min, 90 min, and any two values ​​or any range of any two values.

[0063] The present invention does not have any particular limitations on the raw materials used to adjust the pH; any conventional acid or base raw materials in the art can be used.

[0064] According to the present invention, the cross-linked fiber membrane can be cleaned to remove residual cross-linking agents and other substances. The present invention does not particularly limit the cleaning method, including but not limited to rinsing with water. To improve cleaning efficiency, ultrasonic cleaning is preferred. The ultrasonic conditions are not particularly limited here. For example, the ultrasonic frequency is 20-80 kHz. Preferably, the ultrasonic cleaning time is 1-30 minutes per cycle, more preferably 15-25 minutes per cycle, and the number of cleaning cycles is selected from 1-5 times, preferably 2-4 times.

[0065] According to the present invention, if the superspreadable polypropylene fiber membrane needs to be dried, the drying temperature shall not exceed the glass transition temperature of the amphiphilic polymer. When the processing temperature exceeds the glass transition temperature, the amphiphilic polymer undergoes molecular chain segment movement, which will destroy its self-assembled structure and affect the superspreading performance.

[0066] The above describes the super-spreadable polypropylene fiber membrane of the present invention and its preferred preparation method.

[0067] According to the present invention, preferably, the super-spreadable polypropylene fiber membrane has at least one of the following characteristics:

[0068] The super-spreadable polypropylene fiber membrane achieves a static water contact angle of 0 degrees within 0.005 seconds to 1 second; more preferably, the static water contact angle can reach 0 degrees within 0.005 seconds to 1 second. For example, it can be 0.005 seconds, 0.01 seconds, 0.05 seconds, 0.1 seconds, 0.5 seconds, 0.9 seconds, 1 second, or any two values ​​or any interval between any two values;

[0069] And / or, the maximum size of the spreading area after a 2 μL droplet is spread on the superspreadable polypropylene fiber membrane is not less than 7 mm, the maximum size of the spreading area after a 5 μL droplet is spread on the superspreadable polypropylene fiber membrane is not less than 8 mm, the maximum size of the spreading area after an 8 μL droplet is spread on the superspreadable polypropylene fiber membrane is not less than 12 mm, and the maximum size of the spreading area after a 12 μL droplet is spread on the superspreadable polypropylene fiber membrane is not less than 15 mm.

[0070] According to the present invention, preferably, the super-spreadable polypropylene fiber membrane has a high specific surface area, preferably, the specific surface area of ​​the super-spreadable polypropylene fiber membrane is greater than 0.3 m² / g, and more preferably greater than 0.7 m² / g.

[0071] The method for detecting the maximum size of the droplet spreading area on the fiber membrane can be performed using conventional detection methods in the art. These methods include, but are not limited to, the following: The fiber membrane sample is flatly attached to a glass slide, ensuring the sample remains horizontal during attachment. The slide is then fixed on the sample stage of a contact angle measuring instrument. The droplet volume is controlled by adjusting the instrument; the volume can be 2 μL, 5 μL, 8 μL, or 12 μL. A droplet is placed in the center of the sample. After the contact angle reaches 0 degrees, the glass slide is removed, and the size of the spreading area is measured. The spreading area is approximately circular; its diameter or diagonal can be taken as the maximum size.

[0072] According to the present invention, the time required for the static contact angle between the polypropylene fiber membrane and water to reach 0 degrees can be tested using conventional testing methods in the art. These methods include, but are not limited to, the following: The fiber membrane sample is flatly attached to a glass slide, ensuring the sample remains horizontal during attachment. The slide is then fixed on the sample stage of a contact angle measuring instrument. A water droplet with a volume of less than 2 μL is dropped into the center of the sample. The angle between the solid-liquid interface, through the interior of the droplet, and the vapor-liquid interface at the three-phase interface is measured; this is the static contact angle (referred to as the water contact angle). The time is calculated from the moment the droplet contacts the fiber membrane surface and is lifted off the surface, until the droplet is fully spread and the contact angle reaches 0 degrees. Controlling the volume to less than 2 μL eliminates the influence of gravity, better demonstrating the excellent hydrophilicity and superspreading properties of the polypropylene fiber membrane.

[0073] According to the present invention, the oleophilic fiber membrane can be of various types, as long as it has oleophilic properties and a certain oil flux, it can be used as an oleophilic fiber membrane. It can be made in-house or commercially available.

[0074] According to the present invention, preferably, the static contact angle between the oleophilic fiber membrane and the oil is 0°, and / or the oil flux is not less than 1.0 × 10⁻⁶. 5 L / m 2 •h; The static contact angle between the oleophilic fiber membrane and the oil used in the embodiments of the present invention can all reach 0°.

[0075] Preferably, the oleophilic fiber membrane is selected from at least one of polypropylene fiber membrane and modified polypropylene fiber membrane.

[0076] The superspreadable fiber membrane of this invention has hydrophilic and oleophilic properties, and can be used as both a water separation membrane and an oil separation membrane. As long as the superspreadable polypropylene fiber membrane is moistened with oil before use, it can be used as an oleophilic fiber membrane. More preferably, the oleophilic fiber membrane is the superspreadable polypropylene fiber membrane described in this invention.

[0077] According to the present invention, the water flux of the oil-water separator is not less than 6.0 × 10⁻⁶. 4 L / m2 •h, oil flux not less than 1.0×10 5 L / m 2 •h; preferably, the water flux is not less than 6.5×10 4 L / m 2 •h, oil flux not less than 1.1×10 5 L / m 2 •h; more preferably, the water flux is not less than 7.0×10 4 L / m 2 •h, oil flux not less than 1.2×10 5 L / m 2 The oil-water separation device of the present invention has a high oil-water throughput.

[0078] The water throughput refers to the maximum amount of water that can be separated per hour per square meter by the oil-water separator, and the oil throughput refers to the maximum amount of oil that can be separated per hour per square meter by the oil-water separator.

[0079] The formula for calculating water flux is shown in Equation 1:

[0080] F 水通量 = / V 分离水 AΔt

[0081] Where F 水通量 V is the water flux. 分离水 Let A be the volume of water separated, A be the surface area of ​​the water separation membrane, and Δt be the separation time.

[0082] The formula for calculating oil flux is shown in Equation 2:

[0083] F 油通量 = / V 油离水 AΔt

[0084] Where F 水通量 V is the water flux. 油离水 Let A be the volume of water separated, A be the surface area of ​​the oil separation membrane, and Δt be the separation time.

[0085] like Figure 1 As shown, the oil-water separation device includes a liquid inlet chamber, which is provided with a liquid inlet 1. One end of the liquid inlet chamber is provided with an ultra-spreadable polypropylene fiber membrane 2, and the other end is provided with an oleophilic fiber membrane 3.

[0086] The oil-water separation device further includes a water outlet 4 and an oil outlet 5. The water outlet 4 is connected to the liquid inlet chamber through the super-spreadable polypropylene fiber membrane 2, and the oil outlet 5 is connected to the liquid inlet chamber through the oleophilic fiber membrane. The super-spreadable polypropylene fiber membrane is a super-hydrophilic polypropylene fiber membrane without a layered structure.

[0087] According to the present invention, preferably, a first support layer is provided on one or both sides of the super-spreadable polypropylene fiber membrane; preferably, the water flux of the first support layer is not less than that of the super-spreadable polypropylene fiber membrane, so that it can both support the super-spreadable polypropylene fiber membrane and reduce the water flux.

[0088] According to the present invention, preferably, a second support layer is provided on one or both sides of the oleophilic fiber membrane, and preferably, the oil flux of the second support layer is not less than that of the oleophilic fiber membrane. This provides support for the oleophilic fiber membrane without reducing the oil flux.

[0089] In this invention, the ultra-spreadable polypropylene fiber membrane and the oleophilic fiber membrane are each connected to the cavity wall of the liquid inlet chamber via a sealing assembly. The sealing assembly can be any existing material or technology that provides a sealing function, such as a sealing gasket or sealant.

[0090] A second aspect of the present invention is to provide a method for oil-water separation using the oil-water separation apparatus described in the first aspect, comprising:

[0091] First, wet the super-spreadable polypropylene fiber membrane 2 with water, and preferably wet the oleophilic fiber membrane 3 with oil.

[0092] The oil-water mixture is then transported from the inlet 1 to the inlet chamber. The aqueous phase in the oil-water mixture passes through the super-spreadable polypropylene fiber membrane 2 and flows out from the outlet 4. The oil phase in the oil-water mixture passes through the oleophilic fiber membrane 3 and flows out from the oil outlet 5.

[0093] The separation device is driven by pressure difference or gravity, preferably gravity drive which consumes no energy. The inlet channel is the channel through which oily wastewater (oil-water mixture) enters; the separation channel includes a water channel and an oil channel.

[0094] According to the present invention, the oil-water separation process can be driven by negative pressure and / or gravity, and in the embodiments described below, it is driven by gravity.

[0095] According to the present invention, the driving pressure of the oil-water separation process is greater than 0.01 MPa (water level height 0.1 cm), that is, water above 0.1 cm in height can flow out.

[0096] According to the present invention, in the oil-water separation method, the super-spreadable polypropylene fiber membrane is wetted with clean water. The amount of water used is more than one times the weight of the polypropylene fiber membrane itself to ensure that the super-spreadable polypropylene fiber membrane can be completely wetted with water. Oily wastewater enters the device through the water inlet passage. The oily wastewater comes into contact with the water-wetted super-spreadable polypropylene fiber membrane and the oleophilic fiber membrane. The water in the oily wastewater enters the water passage through the super-spreadable polypropylene fiber membrane. The oil in the oily wastewater enters the oil passage through the oleophilic fiber membrane.

[0097] The oily wastewater can be any mixture of oily liquid and water, with any oil-to-water ratio and any density of oil, which can be lower or higher than that of water. According to the present invention, the oil in the oily wastewater is preferably a low-viscosity oil.

[0098] A third aspect of the present invention is to provide an application of the oil-water separation device described in the first aspect or the method described in the second aspect in the field of oil-water separation treatment.

[0099] The oil-water separation device of this invention achieves efficient separation of oil and water, broadening the application scope of using membrane materials for efficient oil-water separation. The oil-water separation device of this invention is simple, has high oil-water throughput, and possesses extremely high application value.

[0100] Compared with the prior art, the present invention has the following advantages:

[0101] The oil-water separation device of this invention can achieve highly efficient separation of oil and water, with a water throughput higher than most existing oil-water separation technologies. This invention utilizes a polypropylene fiber membrane with water superspreading properties. This polypropylene fiber membrane has fine fibers and a hydrophilic fiber surface. When the superspreading polypropylene fiber membrane is wetted with water, due to the surface tension at the oil-water interface, oil droplets will form near-spherical shapes in the heterogeneous phase. Meanwhile, gaps exist between the fibers inside the fiber membrane. When these gaps are filled with water, oil, due to surface tension, cannot enter the gaps, allowing only water to pass through, thus achieving oil-water separation. Simultaneously, the small fiber diameter inside the superspreading polypropylene fiber membrane can create capillary action. When the fibers are wetted with water, water can be rapidly transferred within the fiber membrane through capillary force, resulting in a high throughput. In other words, after the superspreading polypropylene fiber membrane is wetted with water, it can block oil from passing through, allowing only water to pass, and the water throughput is large. Similarly, when the oleophilic fiber membrane is wetted by oil, only oil can pass through. Thus, oil-water separation is achieved through the action of the super-spreadable polypropylene fiber membrane and the oleophilic fiber membrane.

[0102] Meanwhile, the superspreadable polypropylene fiber membrane used in this invention is an amphiphilic fiber membrane, which can also be used as an oleophilic fiber membrane, and also has a high oil flux. The reason why the polypropylene fiber membrane of this invention possesses the above properties is due to an unexpected discovery during the inventors' research: when the fiber diameter of the polypropylene fiber membrane is less than a certain size, capillary action occurs on the surface and inside of the fiber membrane. During contact or impregnation with the amphiphilic polymer aqueous solution, the solution comes into contact with the polypropylene fiber surface through capillary force or with the help of external force. When the content of the amphiphilic polymer in the solution is not higher than 5 wt%, the amphiphilic polymer molecular chains in the aqueous solution are uniformly dispersed. The oleophilic segments (segments without hydroxyl groups) exhibit good compatibility with the equally oleophilic polypropylene, and self-assemble upon contact with the polypropylene fiber membrane matrix. In this process, the amphiphilic polymer separates the hydrophilic and oleophilic segments; that is, the oleophilic segments coat the polypropylene fiber surface, and the hydrophilic segments are exposed on the polypropylene fiber surface after self-assembly, thus giving the polypropylene fiber membrane hydrophilic properties. By controlling process conditions (such as external force and the concentration of the amphiphilic polymer), thin-layer self-assembly of the amphiphilic polymer on the surface of polypropylene fibers can be achieved. Through the combined action of capillary force and self-assembly, the polypropylene fiber membrane contains polypropylene fibers coated with the amphiphilic polymer, giving the polypropylene fiber membrane superspreading properties. This process can occur better under external force, such as ultrasound, allowing the amphiphilic polymer solution to quickly penetrate between the fibers of the fiber membrane, promoting the contact between the oleophilic segments and the polypropylene fiber surface, thereby accelerating the speed and efficiency of self-assembly. Attached Figure Description

[0103] Figure 1 This is a schematic diagram of an oil-water separation device.

[0104] 1-Liquid inlet; 2-Super-spreadable polypropylene fiber membrane; 3-Oil-loving fiber membrane; 4-Water outlet; 5-Oil outlet. Detailed Implementation

[0105] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0106] The experimental data in the examples were measured using the following instruments and methods:

[0107] The water contact angle and spreading time (spreading time is the time required for the water contact angle to reach 0°) obtained in the example were measured using the German EASYDROP contact angle tester: The fiber membrane was cut into a sample of 1cm×1cm size, and then the sample was flatly attached to a glass slide. During the attachment process, care was taken to keep the sample flat in the horizontal direction. Then the glass slide was placed on the sample stage of the EASYDROP contact angle measuring instrument and fixed. The instrument was adjusted to control the volume of 2μL water droplet to the center of the sample. After 10 seconds, the angle between the solid-liquid interface, through the interior of the droplet, and the vapor-liquid interface at the three-phase interface was measured, which is the static contact angle (abbreviated as water contact angle).

[0108] Water spread area test method: Cut the fiber membrane into 3cm×3cm samples, place the samples flat on a flat glass surface, and then use a Masterflex 78018-10 peristaltic pump to draw different volumes of deionized water droplets onto the surface of the fiber membrane. After the water has spread completely, measure the maximum dimension at both ends of the spread area as the spread dimension.

[0109] Liquid content of hydrophilic polypropylene fiber membrane: Take a dried hydrophilic polypropylene fiber membrane and weigh it. Then rinse the sample with deionized water until there is no foam, and suspend it at 25°C and 30% humidity. After no water droplets fall for 1 minute, weigh it again. The difference between the two weighings divided by the mass after drying is the liquid content of the sample, expressed in multiples.

[0110] The mass content of amphiphilic polymer in the polypropylene fiber membrane obtained in the example: Weigh the unmodified polypropylene nonwoven fabric (m1), process it according to the method listed in the example, and then dry it to obtain the processed polypropylene fiber membrane. Weigh the membrane (m2). The mass content of amphiphilic polymer is (m2-m1) / m2×100%.

[0111] The content of amphiphilic polymer per unit surface area of ​​the polypropylene fiber membrane is determined as follows: First, the sample to be tested is coated with gold. Then, the coated sample is placed on an SEM stage, and a 5μm × 5μm area on the sample is scanned using SEM. Then, the mass fraction of oxygen in this area is determined using EDS energy dispersive spectroscopy, and recorded as w0 and w1 respectively. The oxygen content is calculated using the following formula: W = (w1 - w0) / (M O / M A )×M, where M O M is the relative atomic mass of oxygen. A M is the molecular weight of a single unit of the amphiphilic polymer, M is the areal density of the polypropylene nonwoven fabric, and W is the content of the amphiphilic polymer per unit area of ​​the polypropylene fiber membrane.

[0112] Test method for specific surface area of ​​super-spreadable polypropylene fiber membrane: Use mercury porosimeter to test, weigh a certain mass of sample, transfer it into a dilatometer, then seal and weigh it; put the weighed dilatometer into a low-pressure chamber, and then conduct a high-pressure test, and calculate the specific surface area result through software.

[0113] In the following examples, polyvinyl alcohol (PVA-1799) with a degree of polymerization of 1700 and a degree of alcoholysis of 99%, glutaraldehyde (analytical grade), and hydrochloric acid with a concentration of 36% were all purchased from Sinopharm.

[0114] Preparation of super-spreadable polypropylene fiber membranes

[0115] Preparation Example 1

[0116] Take polypropylene meltblown nonwoven fabric (purchased from Yanshan Petrochemical, specification 25g / m²) 2 Polypropylene (PP) fibers (0.5-8 μm in diameter) were immersed in a 0.3 wt% aqueous solution of polyvinyl alcohol (PVA-1799, glass transition temperature 72℃) at 25℃ and ultrasonically treated at 50 kHz for 30 minutes under a 250W ultrasonic probe. The treated PP meltblown fibers were then crosslinked in a 0.5 wt% glutaraldehyde crosslinking solution (pH 6) at 60℃ for 1 hour. After crosslinking, the PP meltblown fibers were cleaned three times in a 100W ultrasonic water bath at 50 kHz for 20 minutes each time, followed by drying (at 60℃ for 1 hour) to obtain an ultra-spreadable polypropylene fiber membrane.

[0117] The obtained polypropylene fiber membrane was tested for water contact angle, specific surface area, and spreading time. The specific test data are shown in Table 1.

[0118] Preparation Example 2

[0119] A three-layer composite fiber membrane consisting of polypropylene spunbond nonwoven fabric and polypropylene meltblown fabric (purchased from Yanshan Petrochemical, model SMS, specification 50g / m³) was prepared. 2 (The fiber diameter is 0.5-45 micrometers). Except for changing the ultrasonic treatment time when soaking in polyvinyl alcohol aqueous solution to 50 minutes, everything else is the same as in Example 1, and an ultra-spreadable polypropylene fiber membrane is obtained. The specific test data are shown in Table 1.

[0120] Preparation Example 3

[0121] The polypropylene meltblown nonwoven fabric from Preparation Example 1 was immersed in a 0.1 wt% polyvinyl alcohol (from Aladdin, PVA-1799) aqueous solution at 25°C and ultrasonically treated at a frequency of 50 kHz for 30 minutes under a 250 W ultrasonic probe. The treated polypropylene meltblown fabric was then crosslinked in a 0.5 wt% glutaraldehyde crosslinking solution (pH 6) in an 80°C oven for 1 hour. After crosslinking, the polypropylene meltblown fabric was cleaned three times in a 100 W ultrasonic water bath at a frequency of 50 kHz, each time for 20 minutes, and then dried (at 85°C for 1 hour). The glass transition temperature of PVA-1799 is 72°C. Specific test data are shown in Table 1, yielding a modified polypropylene fiber membrane.

[0122] Preparation Example 4

[0123] A 0.8 wt% aqueous solution was prepared using PVA 1750 (purchased from Shandong Jiaying Chemical Technology Co., Ltd.) and deionized water at 90℃. 500 ml of the PVA solution was weighed and mixed with 600 ml of the crosslinking solution to obtain a mixed solution. The crosslinking solution contained 45 ml of glutaraldehyde aqueous solution (50 wt%), as well as acetic acid aqueous solution (10 vol%), methanol aqueous solution (10 vol%), and sulfuric acid aqueous solution (10 vol%), with a volume ratio of 3:2:1. Polypropylene meltblown nonwoven fabric (Sinopec Yanshan Petrochemical, surface density 25 g / m²) was used. 2 The mixture was placed in a mixed solution and vibrated at 150 rpm for 60 minutes at 50°C in a shaking incubator. It was then placed in deionized water for 1 hour to remove residual crosslinking agent and PVA, and finally dried in a 50°C oven for 1 hour to obtain the modified polypropylene fiber membrane. Specific test results are shown in Table 1.

[0124] Preparation Example 5

[0125] The concentration of PVA aqueous solution was changed to 0.1 wt%, the crosslinking agent was changed to boric acid with a mass fraction of 0.5 wt%, and the crosslinking time was 90 minutes. All other operations were the same as in Preparation Example 1. Specific test data are shown in Table 1.

[0126] Example 1

[0127] The super-spreadable polypropylene fiber membrane prepared in Preparation Example 1 was wetted with water and used as the water separation membrane in the separation module (i.e., the oil-water separation device). Polypropylene meltblown nonwoven fabric (purchased from Yanshan Petrochemical, specification 25 g / m²) was used. 2 Fibers with a diameter of 0.5-8 micrometers are used as oil separation membranes.

[0128] A water-wetted, super-spreadable polypropylene fiber membrane and an oil-wetted polypropylene meltblown nonwoven fabric were fixed to the water outlet and oil outlet of the separation component using sealing silicone. 1000 ml of an oil-water mixture (a mixture of hexane and water, with the total volume of the mixture being 100%, water volume being 50%, and hexane mass being 50%) was poured into the water inlet channel, allowing the oil-water mixture to enter the liquid inlet chamber of the separation component. After the mixture came into contact with the water-wetted, super-spreadable polypropylene fiber membrane and the polypropylene meltblown nonwoven fabric, water passed through the water-wetted, super-spreadable polypropylene fiber membrane into the water passage, and oil passed through the oil separation membrane into the oil passage. The water passage and oil passage were connected to a weighable beaker, and the time was recorded. The water flux and oil flux were calculated, and the results are shown in Table 2.

[0129] Example 2

[0130] The super-spreadable polypropylene fiber membrane prepared in Preparation Example 1 was used as the water separation membrane in the separation assembly after being wetted with water, and the super-spreadable polypropylene fiber membrane in Preparation Example 1 was used as the oil separation membrane after being wetted with oil.

[0131] Water-wetted and oil-wetted superspreadable polypropylene fiber membranes were fixed in the separation unit. 1000 ml of an oil-water mixture (a mixture of n-hexane and water, with the total volume of the mixture being 100%, water volume being 50%, and n-hexane mass being 50%) was poured into the inlet water channel, allowing the oil-water mixture to enter the separation unit. After the mixture came into contact with the water-wetted and oil-wetted superspreadable polypropylene fiber membranes, water passed through the water-wetted membrane into the water passage, and oil passed through the oil-wetted membrane into the oil passage. The water and oil passages were connected to weighable beakers, and the time was recorded. The water flux and oil flux were calculated, and the results are shown in Table 2.

[0132] Example 3

[0133] The super-spreadable polypropylene fiber membrane prepared in Preparation Example 2 was used as the water separation membrane in the separation module after being wetted with water, and the super-spreadable polypropylene fiber membrane from Preparation Example 2 was used as the oil separation membrane after being wetted with oil. The water-wetted and oil-wetted super-spreadable polypropylene fiber membranes were fixed in the separation module.

[0134] 1000 ml of an oil-water mixture (crude oil and water mixture, taken from Shengli Oilfield, with the total volume of the mixture being 100%, water volume being 95%, and n-hexane mass being 5%) was poured into the inlet channel, allowing the oil-water mixture to enter the separation unit. After the mixture came into contact with the water-wetted and oil-wetted super-spreadable polypropylene fiber membranes, water passed through the water-wetted super-spreadable polypropylene fiber membrane into the water passage, and oil passed through the oil-wetted super-spreadable polypropylene fiber membrane into the oil passage. The water passage and oil passage were connected to a weighable beaker, and the time was recorded. The water flux and oil flux were calculated, and the results are shown in Table 2.

[0135] Example 4

[0136] The super-spreadable polypropylene fiber membrane of Preparation Example 5 was used instead of the super-spreadable fiber membrane in Example 1 as the water separation membrane, and the other conditions were the same as in Example 1.

[0137] Comparative Example 1

[0138] Polypropylene meltblown nonwoven fabric (purchased from Yanshan Petrochemical, specification 25g / m²) was used. 2 The fiber diameter is 0.5-8 micrometers) to replace the super-spreadable polypropylene fiber membrane in Example 1 as the water separation membrane, and the other conditions are the same, with no water flowing out of the water passage.

[0139] Comparative Example 2

[0140] The modified polypropylene fiber membrane from Preparation Example 3 was used as the water separation membrane instead of the super-spreadable polypropylene fiber membrane from Preparation Example 1 in Example 1. All other conditions were the same as in Example 1. The test results are shown in Table 2.

[0141] Comparative Example 3

[0142] The modified polypropylene fiber membrane from Preparation Example 4 was used as the water separation membrane instead of the superspreadable polypropylene fiber membrane from Preparation Example 1 in Example 2, with all other conditions remaining the same as in Example 2. Since the membrane in Preparation Example 4 could not spread, no water passed through the water passage for an extended period; the test results are shown in Table 2.

[0143] Table 1

[0144]

[0145] Table 2

[0146] Example 1 <![CDATA[7.57×10 4 ]]> <![CDATA[1.21×10 5 ]]> Example 2 <![CDATA[7.58×10 4 ]]> <![CDATA[1.34×10 5 ]]> Example 3 <![CDATA[6.28×10 4 ]]> <![CDATA[1.03×10 5 ]]> Example 4 <![CDATA[6.98×10 4 ]]> <![CDATA[1.15×10 5 ]]> Comparative Example 1 / <![CDATA[1.22×10 4 ]]> Comparative Example 2 / <![CDATA[1.21×10 4 ]]> Comparative Example 3 / <![CDATA[0.83×10 4 ]]>

[0147] As can be seen from the above embodiments, the oil-water separation device of the present invention achieves efficient separation of oil and water, broadening the application scope of using membrane materials to achieve efficient oil-water separation. The oil-water separation device of the present invention is simple, has high oil-water throughput, and has extremely high application value.

[0148] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

[0149] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0150] When this specification uses the prefixes "known to those skilled in the art," "prior art," or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those conventionally used in the art at the time the invention was proposed, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0151] The endpoints and any values ​​of the ranges disclosed in this invention document are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0152] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

[0153] Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas shall be regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider the combination to be obviously unreasonable.

Claims

1. An oil-water separation device, comprising an inlet chamber, wherein an inlet is provided on the inlet chamber, an ultra-spreadable polypropylene fiber membrane is provided at one end of the inlet chamber, and an oleophilic fiber membrane is provided at the other end; The oil-water separation device further includes a water outlet and an oil outlet. The water outlet is connected to the liquid inlet chamber through the ultra-spreadable polypropylene fiber membrane, and the oil outlet is connected to the liquid inlet chamber through the oleophilic fiber membrane. The super-spreadable polypropylene fiber membrane comprises a polypropylene fiber membrane matrix and an amphiphilic polymer. Based on the mass of the super-spreadable polypropylene fiber membrane as 100%, the content of the polypropylene fiber membrane matrix in the super-spreadable polypropylene fiber membrane is 93%-99.99%; the content of the amphiphilic polymer is 0.01%-7%. The amphiphilic polymer is selected from polyvinyl alcohol and / or cross-linked polymers formed by polyvinyl alcohol and a cross-linking agent; the cross-linking agent is selected from at least one of polybasic acids and polybasic aldehydes. The method for preparing the super-spreadable polypropylene fiber membrane includes contacting a polypropylene fiber membrane matrix with a solution containing an amphiphilic polymer under external force, wherein the external force is applied by one or more of the following methods: ultrasonication, rolling, filtration, lamination, and molding; the content of the amphiphilic polymer in the solution is not higher than 5 wt%. The preparation method further includes a drying step after the polypropylene fiber membrane matrix comes into contact with the amphiphilic polymer; The contact temperature and the drying temperature each do not exceed the glass transition temperature of the amphiphilic polymer.

2. The oil-water separation device according to claim 1, characterized in that: Based on the mass of the super-spreadable polypropylene fiber membrane as 100%, the content of the polypropylene fiber membrane matrix in the super-spreadable polypropylene fiber membrane is 95%-99.95%; the content of the amphiphilic polymer is 0.05%-5%; and / or, The super-spreadable polypropylene fiber membrane is a non-layered, superhydrophilic polypropylene fiber membrane; and / or The content of amphiphilic polymer per unit surface area of ​​the super-spreadable polypropylene fiber membrane is 0.005 g / m². 2 -3g / m 2 .

3. The oil-water separation device according to claim 1, characterized in that: The content of amphiphilic polymer per unit surface area of ​​the super-spreadable polypropylene fiber membrane is 0.005 g / m². 2 -2g / m 2 .

4. The oil-water separation device according to claim 1, characterized in that: The fiber diameter in the super-spreadable polypropylene fiber membrane is less than 20 micrometers; and / or, The crosslinking agent is glutaraldehyde and / or boric acid; and / or, The super-spreadable polypropylene fiber membrane contains polypropylene fibers coated with an amphiphilic polymer.

5. The oil-water separation device according to claim 1, characterized in that: The fiber diameter in the super-spreadable polypropylene fiber membrane is less than 10 micrometers; and / or, The super-spreadable polypropylene fiber membrane contains polypropylene fibers coated with an amphiphilic polymer, which is self-assembled onto the polypropylene fibers by capillary force.

6. The oil-water separation device according to claim 1, characterized in that: The fiber diameter in the super-spreadable polypropylene fiber membrane is 0.1-10 micrometers.

7. The oil-water separation device according to claim 1, characterized in that: The contact utilizes intermolecular forces to enable the amphiphilic polymer to self-assemble on the surface of the polypropylene fiber membrane, resulting in a polypropylene fiber membrane coated with the amphiphilic polymer.

8. The oil-water separation device according to claim 1, characterized in that: The content of amphiphilic polymers in the solution is 0.05-4.5 wt%.

9. The oil-water separation device according to claim 1, characterized in that: The amphiphilic polymer content in the solution is 0.1-4.5 wt%.

10. The oil-water separation device according to claim 1, characterized in that: When the amphiphilic polymer on the superspreadable polypropylene fiber membrane is a crosslinked polymer formed by polyvinyl alcohol and a crosslinking agent, the preparation method of the superspreadable polypropylene fiber membrane includes contacting the polypropylene fiber membrane matrix with a solution containing the amphiphilic polymer under the action of external force, and then subjecting the polypropylene fiber membrane obtained after contacting the polypropylene fiber membrane matrix with the amphiphilic polymer to a crosslinking reaction in a solution containing a crosslinking agent.

11. The oil-water separation device according to any one of claims 1-10, characterized in that: The super-spreadable polypropylene fiber membrane has at least one of the following characteristics: The aforementioned super-spreadable polypropylene fiber membrane achieves a static water contact angle of 0 degrees within no more than 1 second; and / or, The maximum size of the spreading area after a 2μL droplet is spread on the superspreadable polypropylene fiber membrane is not less than 7mm, the maximum size of the spreading area after a 5μL droplet is spread on the superspreadable polypropylene fiber membrane is not less than 8mm, the maximum size of the spreading area after an 8μL droplet is spread on the superspreadable polypropylene fiber membrane is not less than 12mm, and the maximum size of the spreading area after a 12μL droplet is spread on the superspreadable polypropylene fiber membrane is not less than 15mm.

12. The oil-water separation device according to any one of claims 1-10, characterized in that: The super-spreadable polypropylene fiber membrane achieves a static contact angle of 0 degrees with water within 0.005 seconds to 1 second.

13. The oil-water separation device according to any one of claims 1-10, characterized in that: The static contact angle between the oleophilic fiber membrane and the oil can be 0°, and / or the oil flux is not less than 1.0 × 10⁻⁶. 5 L / m 2 ·h; and / or, The water flux of the oil-water separator is not less than 6.0 × 10⁻⁶. 4 L / m 2 •h, oil flux not less than 1.0×10 5 L / m 2 ·h.

14. The oil-water separator according to any one of claims 1-10, characterized in that: The static contact angle between the oleophilic fiber membrane and the oil can be 0°, and / or the oil flux is not less than 1.0 × 10⁻⁶. 5 L / m 2 •h; the oleophilic fiber membrane is selected from at least one of polypropylene fiber membranes and modified polypropylene fiber membranes; and / or, The water flux of the oil-water separator is not less than 6.5 × 10⁻⁶. 4 L / m 2 •h, oil flux not less than 1.1×10 5 L / m 2 ·h.

15. The oil-water separation device according to any one of claims 1-10, characterized in that: The water flux of the oil-water separator is not less than 7.0 × 10⁻⁶. 4 L / m 2 •h, oil flux not less than 1.2×10 5 L / m 2 ·h.

16. The oil-water separation device according to any one of claims 1-10, characterized in that: The super-spreadable polypropylene fiber membrane has a first support layer on one or both sides; and / or, A second support layer is provided on one or both sides of the oleophilic fiber membrane; and / or, The super-spreadable polypropylene fiber membrane and the oleophilic fiber membrane are each connected to the cavity wall of the liquid inlet chamber via a sealing assembly.

17. The oil-water separation device according to any one of claims 1-10, characterized in that: A first support layer is provided on one or both sides of the ultra-spreadable polypropylene fiber membrane; the water flux of the first support layer is not less than that of the ultra-spreadable polypropylene fiber membrane; and / or, A second support layer is provided on one or both sides of the oleophilic fiber membrane, and the oil flux of the second support layer is not less than that of the oleophilic fiber membrane.

18. A method for oil-water separation using the oil-water separation apparatus according to any one of claims 1-17, comprising: First, wet the super-spreadable polypropylene fiber membrane with water; The oil-water mixture is then transported from the inlet to the inlet chamber. The aqueous phase in the oil-water mixture passes through the super-spreadable polypropylene fiber membrane and flows out from the outlet. The oil phase in the oil-water mixture passes through the oleophilic fiber membrane and flows out from the oil outlet.

19. The oil-water separation method according to claim 18, characterized in that: The oil-water separation process is driven by negative pressure and / or gravity.

20. The application of an oil-water separation device according to any one of claims 1-17 or the method according to claim 18 or 19 in the field of oil-water separation treatment.

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