CN106943891B - Pollution-resistant composite membrane, preparation method thereof and oil-water emulsion separation method - Google Patents
Pollution-resistant composite membrane, preparation method thereof and oil-water emulsion separation method Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0081—After-treatment of organic or inorganic membranes
- B01D67/0088—Physical treatment with compounds, e.g. swelling, coating or impregnation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/12—Composite membranes; Ultra-thin membranes
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
Abstract
A pollution-resistant composite membrane, a preparation method thereof and an oil-water emulsion separation method. The invention discloses a pollution-resistant composite membrane with corresponding charge performance and capable of respectively aiming at different charged oil-water emulsions, a preparation method thereof and an oil-water emulsion separation method aiming at different charge performance, wherein the pollution-resistant composite membrane comprises a base membrane and an effective separation layer coated on the inner surface of the base membrane, the effective separation layer is a sulfonated high-molecular coating for screening and charge repulsion of negatively charged oil-water emulsions or an aminated high-molecular coating for screening and charge repulsion of positively charged oil-water emulsions, and further the composite membrane can have the charge performance of negative electricity or positive electricity after being treated and adsorbed by a surfactant solution containing anions or cations. The composite membrane disclosed by the invention can remove emulsified oil in different charge states and has high pollution resistance, so that the emulsified oil in a water body is effectively intercepted, the effluent quality is improved, and the treatment cost is low.
Description
Technical Field
The invention belongs to the field of water treatment, and particularly relates to a pollution-resistant composite membrane material for removing oil with different electric charges in wastewater, and a preparation method and application of the material.
Background
Pollution of oily wastewater can cause destructive damage to an ecosystem and potential harm to human health. With the development of industry, the oil recovery amount is larger and larger, but due to the development lag of various technologies, incomplete management and the like, a large amount of oil enters a water body to cause pollution. The pollution of oily wastewater is mainly manifested by affecting drinking water resources and groundwater resources, harming aquatic resources, harming human health, polluting the atmosphere, affecting crop production, destroying natural landscapes, and even possibly causing safety problems due to combustion of coalesced oil products. In view of the pollution of oily wastewater, the highest allowable discharge concentration of oily wastewater in China is 10 mg/L.
The main component in the oily wastewater is emulsified oil, and the removal of the emulsified oil is the most critical. The emulsified oil is an extremely fine oil drop with the particle size of 0.1-20 microns, and is dispersed in a water body in a stable form due to the existence of the surfactant. The most common treatment methods at present comprise physical, chemical, biological, membrane separation and integrated processes in various ways.
The membrane material for oil-water separation in the common membrane technology separation method is a porous membrane (microfiltration and ultrafiltration), which can remove emulsified oil, but has low removal rate for other substances. But the surface of the membrane material is easy to adhere emulsified oil to form membrane pollution, so that the quality of effluent is seriously reduced, the recoverability of the membrane performance is low, the stability of long-term operation is difficult to solve, the application cost of the microfiltration ultrafiltration membrane is increased, and the treatment efficiency is reduced. And is also not beneficial to the application of long-term stable operation in areas with serious oil-water pollution. Compared with microfiltration ultrafiltration, a Nanofiltration (NF) membrane material is also used for treating oil-water emulsion, the nanofiltration membrane has the advantages of small porosity, smooth surface, pollution resistance and the like, and the nanofiltration membrane also has the separation effect on multivalent ions, can partially remove organic matters and high-valence salts while realizing oil-water separation, has relatively low energy consumption, and is a membrane material with better separation effect compared with a porous membrane material.
Among various methods, the coating method is to directly coat the oil-containing charged polymer dilute solution on the surface of a base film, and then compound an ultrathin layer with the function of pollution resistance on the surface of the treated base film, wherein the thinnest ultrathin layer can reach several nanometers, so that transmembrane pressure difference and operating pressure are greatly reduced; the flat surface also improves the contamination resistance of the filter so that the flux does not decay or decays slightly.
The oily wastewater exists in a stable manner by using an anionic surfactant and a cationic surfactant, so that the coating composite membranes with different charge performances can realize effective interception of oil drops (mainly emulsified oil) and obvious pollution resistance due to the effects of charge repulsion, sieving, smooth surface and the like. However, the research and application of the composite membrane for oil-water emulsion separation with different charge properties have not been provided, and correspondingly, the preparation method and application technology of the composite membrane have not been provided with a corresponding pollution-resistant membrane separation material for removing oil-water emulsions with different charge properties from oil-containing wastewater.
Disclosure of Invention
In view of the problems of the prior art, the present invention is to provide a contamination-resistant composite membrane with corresponding charge performance for different charged oil-water emulsions, a preparation method thereof, and a method for separating oil-water emulsions with different charge performance. The composite membrane disclosed by the invention can remove emulsified oil in different charge states and has high pollution resistance, so that the emulsified oil in a water body is effectively intercepted, the effluent quality is improved, and the treatment cost is low.
The invention discloses a pollution-resistant composite membrane, which comprises a base membrane and an effective separation layer coated on the inner surface of the base membrane; the effective separation layer is a sulfonated high-molecular coating used for screening and charge repulsion of negatively charged oil-water emulsion or an aminated high-molecular coating used for screening and charge repulsion of positively charged oil-water emulsion.
Furthermore, the composite membrane has negative or positive charge performance after being treated and adsorbed by a surfactant solution containing anions or cations.
Furthermore, the effective separation layer thickness of the sulfonated or aminated polymer coating composite membrane is 0.01-20 μm. Preferably, the thickness of the effective separation layer is 1-20 μm.
Further, the sulfonated polymer is one or more of sulfonated polyether ether ketone, sulfonated polystyrene, sulfonated polyaniline or sulfonated polysulfone, and the aminated polymer is one or more of sulfonated polyether ether ketone grafted with amino, aminated polyether ether ketone, amino polystyrene, aminated modified polyaniline or aminated polysulfone.
Further, the material of the base film is a high molecular polymer which can perform adsorption with a surfactant. Preferably, the material of the base film may be selected from polyethersulfone, polysulfone, polyacrylonitrile, polyvinyl chloride, polyethylene or polyvinylidene fluoride; the solvent is one or more of methanol, ethanol, acetone, N, N-dimethylformamide, N, N-dimethylacetamide, hexane and ethyl acetate.
Further, the base membrane may be a hollow fiber membrane, a tubular membrane or a flat sheet membrane.
The invention also discloses a method for preparing the pollution-resistant composite membrane by a polymer coating method, which comprises the following steps of dissolving sulfonated or aminated polymer in a solvent to prepare a coating solution, and then coating the coating solution on the inner surface of the base membrane to obtain the composite membrane.
Further, after the obtained composite membrane is immersed in a surfactant solution containing anions or cations for treatment and adsorption, the composite membrane has negative or positive charge performance after adsorbing the surfactant.
Further, the sulfonated macromolecules are one or more of sulfonated polyether ether ketone, sulfonated polystyrene, sulfonated polyaniline or sulfonated polysulfone, and the aminated macromolecules are one or more of sulfonated polyether ether ketone grafted with amino groups, aminated polyether ether ketone, amino polystyrene, aminated modified polyaniline or aminated polysulfone; the solvent is one or more of methanol, ethanol, acetone, N, N-dimethylformamide, N, N-dimethylacetamide, hexane and ethyl acetate; the mass percentage concentration of the sulfonated or aminated high molecule in the coating solution is 0.01-10%. Preferably, the mass percentage concentration of the sulfonated or aminated polymer in the coating solution is 0.5-10%.
Further, the coating time is 1-30 s.
Further, the surfactant is one or more of sodium polyalkyl sulfonate, sodium polyalkyl benzene sulfonate and a polyalkyl quaternary ammonium compound.
The invention also discloses an oil-water emulsion separation method aiming at different charge performances based on the composite membrane, which adopts the pollution-resistant composite membrane treated by the surfactant solution and adsorbed to treat the water body; or any one of the pollution-resistant composite membranes is used for treating the water body containing the cationic surfactant, wherein the composite membrane with negative charges is used for treating the water body containing the anionic surfactant after being treated and adsorbed by the solution containing the anionic surfactant, and the composite membrane with positive charges is used for treating the water body containing the cationic surfactant after being treated and adsorbed by the solution containing the cationic surfactant.
Further, the surfactant is one or more of sodium polyalkyl sulfonate, sodium polyalkyl benzene sulfonate and a polyalkyl quaternary ammonium compound. The solvent of the surfactant solution is mainly an aqueous solution, facing the water treatment system. General surfactants can be adsorbed.
Compared with the traditional treatment mode that the membrane permeation flux is continuously reduced and the effluent quality is reduced in the treatment process, the invention has the following beneficial effects:
(1) the pollution-resistant composite membrane disclosed by the invention adopts the hollow fiber composite nanofiltration membrane manufactured by the sulfonated or aminated high-molecular coating as an effective separation layer of the inner surface of the base membrane, can remove emulsified oil in different charge states, has high pollution resistance, and improves the flux of permeating water to a certain extent.
(2) The method for adsorbing the surfactant on the composite membrane can improve the flux of the material, can increase the charge of the membrane material after adsorption, and has a certain effect on improving the anti-pollution performance.
(3) The pollution-resistant composite membrane is simple in manufacturing process, can be prepared by adopting the existing high-molecular coating method, and has lower overall cost than reverse osmosis microfiltration, ultrafiltration or nanofiltration membranes.
(4) The pollution-resistant composite membrane disclosed by the invention can be applied to oil removal in oily wastewater, and in the application process, compared with the current commercial nanofiltration membrane, the charged coating polymer adopted in the invention has higher hydrophilicity and low operation pressure. The traditional composite membrane, such as microfiltration, ultrafiltration, nanofiltration and the like, is used for draining water by pumping water into a composite membrane component at an operating pressure of 3-10 bar for one-stage or multi-stage permeation, but the pollution-resistant composite membrane disclosed by the invention has no special requirement on the operating pressure.
(5) The penetrating fluid treated by the pollution-resistant composite membrane can reach the first-level discharge standard of Integrated wastewater discharge Standard (GB8978-1996) in China.
Drawings
Fig. 1 is a schematic structural diagram of a primary nanofiltration device of the invention.
In the figure, 1: raw material pool, 1-1: permeate, 2: primary filtration device, 3: pressure pump, 4: nanofiltration component, 5: regulating valve, 6: and (4) draining the water valve.
Fig. 2 is a schematic structural diagram of the secondary nanofiltration device of the invention.
In the figure, 1: raw material pool, 1-1: a second-stage nanofiltration liquid pool (first-stage penetrating liquid) and 1-2: a second-stage nanofiltration penetrating fluid, 2: primary filtration device, 3: pressure pump, 4: a first-stage nanofiltration component, 4-1: and a secondary nanofiltration component.
Detailed Description
The following description of the embodiments of the present invention is provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
The embodiment discloses a pollution-resistant composite membrane, which is prepared by adopting a high-molecular coating method and comprises a base membrane and an effective separation layer. The base membrane can be an ultrafiltration membrane base membrane and an ultrafiltration membrane base membrane of a hollow fiber membrane, a tubular membrane or a flat membrane. The inner surface of the base film is coated with an effective separation layer which is a sulfonated high-molecular coating or an aminated high-molecular coating. The effective separation layer has a thickness of 0.01 to 20 μm, preferably 1 to 20 μm.
The sulfonated polymer coating film material has a screening effect and a charge repulsion effect on the negatively charged oil-water emulsion, and the aminated polymer coating film material has a screening effect and a charge repulsion effect on the positively charged oil-water emulsion, so that the removal of the oil-water emulsions with different charge properties and the improvement of the anti-pollution performance are realized, and the sulfonated polymer coating film material has higher water yield and can resist the pollution of different charged emulsified oils under the condition of lower pressure of a commercial nanofiltration membrane.
Furthermore, the water permeation flux of the composite membrane material can be improved under the condition of adding the surfactant, and the oily wastewater can be efficiently treated. The obtained composite membrane can be immersed in a surfactant solution containing anions or cations for treatment and adsorption, so that the composite membrane has a negative or positive charge performance.
The embodiment also discloses a preparation method of the pollution-resistant composite membrane, which takes a hollow fiber sulfonated or aminated high-molecular coating composite nanofiltration membrane as an example and is prepared by the following steps: dissolving sulfonated or aminated polymer in solvent to prepare coating solution; then coating the coating solution on the inner surface of the nanofiltration base membrane to obtain a composite membrane; and carrying out heat treatment on the obtained composite membrane for 5-10 hours at the temperature of 50-70 ℃, and drying to obtain the sulfonated or aminated polymer coating composite nanofiltration membrane.
Wherein, the mass percentage concentration of the sulfonated or aminated polymer in the coating solution is 0.01-10%, preferably 0.5-10%. The sulfonated polymer is selected from sulfonated polyether ether ketone, sulfonated polystyrene, sulfonated polyaniline and sulfonated polysulfone; or the aminated polymer is selected from one or more of sulfonated polyether ether ketone grafted with amino, aminated polyether ether ketone, amino polystyrene, aminated modified polyaniline or aminated polysulfone. The solvent of the coating solution is selected from one or more of methanol, ethanol, acetone, tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide, hexane and ethyl acetate.
In the embodiment, the effective separation layer thickness of the hollow fiber sulfonated or aminated high-molecular coating composite nanofiltration membrane is 0.01-20 mu m, and preferably 1-20 mu m. The thickness thereof can be controlled by the coating solution concentration, the coating time and the number of coating times.
When the surface of the nanofiltration base membrane is coated, the coating solution is immersed in the inner cavity of the membrane for a single time or is circularly coated in the inner cavity of the membrane for multiple times. Especially, when the rejection rate of salt or soluble organic matters is not high, the coating can be carried out for multiple times so as to improve the rejection rate of dissolved matters. The retention rate of the material after multiple coating is increased from 70 percent to 90 percent
The coating time of the coating solution on the nanofiltration base membrane is 1-30 s. The coating time has certain influence on the thickness, the water permeation flux and the retention rate. Generally, the longer the coating time, the thicker the thickness, the lower the water flux and the higher the rejection, and therefore the coating time also needs to be controlled as desired, but to some extent this amount does not vary much.
The material of the basement membrane is a high molecular polymer which can generate adsorption with a surfactant. The base membrane may be a hollow fiber membrane, a tubular membrane, or a flat sheet membrane. In the embodiment, the material of the hollow fiber ultrafiltration basal membrane is selected from one or more of polyethersulfone, polysulfone, polyacrylonitrile, polyvinyl chloride, polyethylene or polyvinylidene fluoride.
The surfactant is selected from sodium polyalkyl sulfonate, sodium polyalkyl benzene sulfonate and quaternary ammonium polyalkyl compound.
The sulfonated polymer or aminated polymer coating is adopted in the invention, so that the composite membrane has the charge performance of negative electricity or positive electricity, and the pollution resistance of the composite membrane to oil-water emulsion treatment is improved. The sulfonated polymer or the aminated polymer has a certain adsorption effect on the surfactant, so that pollution resistance is achieved, and the treatment flux is improved. It is worth noting that the main purpose of the surfactant adsorption is to improve the flux of the material, but the adsorption will increase the charge capacity of the membrane material, and has a certain effect on improving the anti-pollution performance.
The embodiment also discloses an oil-water emulsion separation method aiming at different charge performances, namely the application of the pollution-resistant composite membrane disclosed by the invention in the field of oily wastewater treatment. The pollution-resistant composite membrane is suitable for treating oily wastewater with positively or negatively charged emulsified oil in a water body, and is applied to removing the emulsified oil in the water body.
And pumping the oily wastewater into a composite nanofiltration membrane component containing a hollow fiber sulfonated polymer coating or an aminated polymer coating through a pressure pump under the operation pressure of 3-10 bar to perform one-stage or multi-stage water permeation. When the method is applied specifically, the first-stage permeation effluent treatment is adopted when the oil content concentration in the water body is lower than 10,000ppm, and the second-stage or more-stage permeation effluent treatment can be adopted when the oil content concentration in the water body is higher than 10,000 ppm.
The composite membrane can effectively retain emulsified oil in wastewater, and the oil content in the treated water body is 1-10, 000 mg/L. Under the condition that the operating pressure for removing oil from wastewater is only 3-10 bar, the retention rate of oil is more than 95%, and the amount of water permeated is large and is from 10L/m2H.bar can be increased by more than several times, and compared with the traditional microfiltration ultrafiltration membrane, the microfiltration ultrafiltration membrane has no special requirement on the operation pressure, can obtain higher permeation water flux under lower operation pressure, and simultaneously obtains extremely high oil retention rate and certain salt retention rate.
The composite membrane provided by the invention removes charged oil in wastewater by a one-step method, increases the anti-pollution performance, and improves the permeation water flux to a certain extent, so that the composite membrane is a simple and efficient oil-water separation material. If the positive and load electric oil in the wastewater needs to be removed simultaneously, the treatment can be carried out by two composite membranes with charged properties in sequence, for example, the two-step treatment can be carried out by adopting the device shown in the attached figure 2.
The composite membrane has simple preparation process, the treated penetrating fluid can reach the industrial wastewater discharge standard, and compared with a microfiltration ultrafiltration membrane, the composite membrane has good pollution resistance, and when the oil-water emulsion with stable surfactant is treated, the penetrating water flux is high and can be improved to a certain extent. The composite membrane is used for treating the oily wastewater, so that the water environment is improved, the cost can be effectively saved, high-valence salt, suspended substances and the like in the oily wastewater can be further removed, the treatment efficiency is high, the operation cost is low, and the composite membrane is convenient for various occasions, particularly for areas with large discharge amount of the oily wastewater and strict discharge requirements.
In order to more clearly illustrate the technical scheme of the invention, the composite film oil removing process of the invention is further described with reference to the accompanying drawings and specific examples:
in the first-stage nanofiltration device shown in fig. 1, oily wastewater in a raw material-containing pool 1 is simply filtered by a primary filtering device 2, and is pressurized by a pressure pump 3 and then enters a nanofiltration component 4 of a composite membrane to form produced water and concentrated drainage water, wherein the concentrated drainage water can flow back or be directly discharged, and the degree of scarcity of water resources depends.
The secondary nanofiltration device shown in fig. 2 allows the primary nanofiltration permeate to be further processed by the secondary nanofiltration device in a manner similar to the primary nanofiltration device and is not redundant here.
Example 1
Dissolving sulfonated polyether ether ketone in methanol solution to prepare solution with sulfonated high molecular concentration of 0.01%. The composite membrane is coated on a PVDF flat base membrane (the inner diameter and the outer diameter are respectively 0.9mm and 1.4mm) by adopting a single coating, the composite membrane with an effective coating (namely an effective separation layer) is obtained by treating the membrane for 6 hours at the temperature of 65 ℃, the effective coating thickness of a sulfonated polyether-ether-ketone composite nanofiltration membrane is 0.01 mu m, and the nanofiltration membrane is assembled into a hollow fiber membrane component for deoiling by utilizing the process shown in the attached figure 1.
The raw material liquid is oily wastewater, and sodium dodecyl sulfate is added to obtain stable emulsified oil. The synthetic emulsified oil used in the experiment and used in the following examples is the emulsified oil which is the main component of the waste water itself in the actual use process. During the operation, the pressure pump and the valve were adjusted to a pressure of 3 bar. The oil content in the permeating water can not be detected, and the permeating water meets the first-level discharge standard of Integrated wastewater discharge Standard (GB8978 + 1996). The permeation flux of water is not attenuated and rises to a certain extent in the running process of the device.The lowest water yield of the membrane module in the device is 34.5LMH, namely 11.5L/m2·h·bar。
Example 2
Dissolving sulfonated polyether sulfone in a methanol solution to prepare a coating solution with the high molecular concentration of 5.0%, coating the coating solution on a PES (polyether sulfone) flat base membrane (the MWCO of the base membrane is 100000Da, and the internal and external diameter ratio is 0.9/1.3mm), carrying out post-treatment on the membrane for 6 hours in a 65-DEG environment to obtain a composite membrane, wherein the effective coating thickness of the sulfonated polyether ether ketone composite nanofiltration membrane is 1 mu m, and assembling the nanofiltration membrane into a composite membrane assembly to carry out oil removal by using the process shown in the attached figure 1.
The raw material liquid is oily wastewater, and the stable emulsified oil is obtained by adding sodium hexadecyl sulfonate. During the operation, the pressure pump and the valve were adjusted to 6 bar. The oil content in the permeating water can not be detected, and the permeating water meets the first-class discharge standard of Integrated wastewater discharge Standard (GB 8978-1996). The permeation flux of water is not attenuated and rises to a certain extent in the running process of the device. The minimum water output of the membrane module in the apparatus was 69 LMH.
Example 3
Dissolving sulfonated polyether ether ketone in a methanol solution to prepare a coating solution with the high molecular concentration of 10%, coating the coating solution on a polypropylene cyanide tubular base membrane (the inner diameter and the outer diameter are 0.7/1.1mm) by adopting a circulating coating, blowing the coating solution by hot air at the temperature of about 60 ℃ for 6 hours to obtain a composite membrane, wherein the effective coating thickness of the sulfonated polyether ether ketone composite nanofiltration membrane is 20 mu m, and assembling the nanofiltration membrane into a composite membrane assembly to remove oil by the process shown in the attached figure 1.
The raw material liquid is oily wastewater, and tetradecyl sodium sulfonate is added to obtain stable emulsified oil. During the operation, the pressure pump and the valve were adjusted to a pressure of 8 bar. The oil content in the permeating water can not be detected, and the permeating water meets the first-class discharge standard of Integrated wastewater discharge Standard (GB 8978-1996). The permeation flux of water is not attenuated and rises to a certain extent in the running process of the device. The minimum water yield of the membrane module in the apparatus was 80.5 LMH.
Example 4
Dissolving amino polystyrene in a methanol solution to prepare a coating solution with the high molecular concentration of 1.5%, coating the coating solution on a polyacrylonitrile hollow fiber ultrafiltration base membrane (the inner diameter and the outer diameter are 0.7/1.1mm) by adopting a circulating coating, blowing the coating solution by hot air at about 60 ℃ for 6 hours to obtain a composite membrane, wherein the effective coating thickness of the amino polystyrene composite nanofiltration membrane is 5-6 mu m, and assembling the nanofiltration membrane into a composite membrane assembly to remove oil by utilizing the process shown in the attached figure 1.
The raw material liquid is oily wastewater, and tetradecane dimethyl benzyl ammonium chloride is added to obtain stable emulsified oil. During the operation, the pressure pump and the valve were adjusted to a pressure of 8 bar. The oil content in the permeating water is 3mg/L, which meets the first grade discharge standard of Integrated wastewater discharge Standard (GB8978 + 1996). The permeation flux of water is not attenuated during the operation of the device. The minimum water yield of the membrane module in the apparatus was 80.5 LMH.
The embodiment has the advantages that the hollow fiber membrane is used as the base membrane, the hollow fiber composite nanofiltration membrane is manufactured by utilizing the sulfonated or aminated high molecular coating, and the hollow fiber composite nanofiltration membrane is applied to oil removal in oily wastewater. The nanofiltration membrane is simple in manufacturing process, the treated penetrating fluid can reach the first-level discharge standard of the Integrated wastewater discharge Standard (GB8978 & 1996) in China, and the nanofiltration membrane has excellent pollution resistance in the treatment process and can improve the penetrating water flux to a certain extent. Compared with the current commercial nanofiltration membrane, the operation pressure is low, the water flux is high, and the cost can be effectively saved while the sewage discharge is improved by separating the oil-water emulsion.
While the invention has been described with respect to a preferred embodiment, it is not intended to be limited to the embodiment, but rather to the embodiment in any form or material, it is to be understood that various modifications and additions may be made therein by those skilled in the art without departing from the scope of the invention as defined in the appended claims. Those skilled in the art can make various changes, modifications and equivalent arrangements, which are equivalent to the embodiments of the present invention, without departing from the spirit and scope of the present invention, and which may be made by utilizing the techniques disclosed above; meanwhile, any changes, modifications and variations of the above-described embodiments, which are equivalent to those of the technical spirit of the present invention, are also within the scope of the technical solution of the present invention.
Claims (6)
1. An oil-water emulsion separation method aiming at different charge performances is characterized in that: treating the oily wastewater water body added with the cationic surfactant or the anionic surfactant by adopting a pollution-resistant composite membrane; the pollution-resistant composite film comprises a base film and an effective separation layer coated on the inner surface of the base film; the effective separation layer is a sulfonated high-molecular coating used for screening and charge repulsion of negatively charged oil-water emulsion in the water body or an aminated high-molecular coating used for screening and charge repulsion of positively charged oil-water emulsion in the water body; the processing method specifically comprises the following steps:
treating and adsorbing the composite membrane with the sulfonated high-molecular coating as an effective separation layer by a solution containing an anionic surfactant and carrying out negative charge, and then treating a water body containing the anionic surfactant;
treating and adsorbing the composite membrane with the effective separation layer of the aminated high-molecular coating by a solution containing a cationic surfactant and carrying out positive charge, and then treating the water body containing the cationic surfactant.
2. The method for separating an oil-water emulsion according to claim 1, wherein: the effective separation layer thickness of the sulfonated or aminated polymer coating composite membrane is 0.01-20 mu m.
3. The method for separating an oil-water emulsion according to claim 1, wherein: the effective separation layer thickness of the sulfonated or aminated polymer coating composite membrane is 1-20 mu m.
4. The method for separating an oil-water emulsion according to claim 1, wherein: the sulfonated polymer is one or more of sulfonated polyether ether ketone, sulfonated polystyrene, sulfonated polyaniline or sulfonated polysulfone, and the aminated polymer is one or more of sulfonated polyether ether ketone grafted with amino, aminated polyether ether ketone, amino polystyrene, aminated modified polyaniline or aminated polysulfone.
5. The method for separating an oil-water emulsion according to claim 1, wherein: the material of the basement membrane is a high molecular polymer which can generate adsorption with a surfactant.
6. The method for separating an oil-water emulsion according to any one of claims 1 to 5, wherein: the composite membrane is prepared by a high-molecular coating method; wherein: the solute in the coating solution for preparing the effective separation layer is sulfonated or aminated macromolecule with the mass percent concentration of 0.01-10%; the solvent in the coating solution for preparing the effective separation layer is one or more of methanol, ethanol, acetone, N, N-dimethylformamide, N, N-dimethylacetamide, hexane and ethyl acetate.
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