WO2023185303A1 - 一种纳滤复合膜及其制备方法 - Google Patents

一种纳滤复合膜及其制备方法 Download PDF

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WO2023185303A1
WO2023185303A1 PCT/CN2023/076667 CN2023076667W WO2023185303A1 WO 2023185303 A1 WO2023185303 A1 WO 2023185303A1 CN 2023076667 W CN2023076667 W CN 2023076667W WO 2023185303 A1 WO2023185303 A1 WO 2023185303A1
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graphene oxide
porous substrate
composite membrane
nanofiltration composite
preparing
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PCT/CN2023/076667
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English (en)
French (fr)
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吴桐
王琪
李旭
刘练波
郜时旺
程阿超
何忠
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中国华能集团清洁能源技术研究院有限公司
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Publication of WO2023185303A1 publication Critical patent/WO2023185303A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • 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
    • 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
    • B01D67/0039—Inorganic membrane manufacture
    • 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
    • B01D67/0079—Manufacture of membranes comprising organic and inorganic components
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02—Inorganic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02—Inorganic material
    • B01D71/021—Carbon
    • 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

Definitions

  • the present application relates to the field of membrane separation technology, and specifically to a nanofiltration composite membrane and a preparation method thereof.
  • Membrane separation is an emerging separation technology that has been widely used in industrial and urban waste liquid treatment, organic pollutant removal, heavy metal ion removal, ultrapure water preparation, and gas separation.
  • the membrane separation process has the advantages of low energy consumption, high selectivity, no phase change, simple and flexible equipment, and no secondary pollution. It is very suitable for treating waste liquid generated in the process of synthesizing low-carbon olefins from CO2 .
  • the graphene oxide membrane can be regarded as a capillary network with two-dimensional nanochannels. By regulating the interlayer spacing between the graphene oxide nanosheets, the screening of molecules or ions of different sizes can be achieved.
  • the surface of graphene oxide contains a large number of hydrophilic oxygen-containing functional groups. The oxygen-containing functional groups easily adsorb water molecules and cause a swelling effect, causing the interlayer spacing between graphene oxide nanosheets to rapidly increase, thereby reducing the separation of the graphene oxide film. effectiveness and structural stability. For this reason, hydrazine hydrate or hydriodic acid is usually used to reduce graphene oxide to improve the separation effect and structural stability of the graphene oxide membrane.
  • the technical problem to be solved by this application is to overcome the defect that existing graphene oxide membranes cannot achieve sieving of molecules or ions of different sizes, thereby providing a nanofiltration composite membrane and a preparation method thereof.
  • the present application provides a method for preparing a nanofiltration composite membrane, which includes: preparing a graphene oxide dispersion; adding tannic acid to the graphene oxide dispersion to perform a reduction reaction, so that the graphene oxide dispersion Graphene oxide is at least partially reduced; the graphene oxide dispersion is suction filtered, and the reduced graphene oxide is deposited on the first porous substrate to obtain a graphene oxide layer; the graphene oxide layer is Drying is performed; and a second porous substrate is provided on the side of the graphene oxide layer facing away from the first porous substrate.
  • the mass ratio of tannic acid to graphene oxide is 0.03-5.
  • the mass ratio of tannic acid to graphene oxide is 0.1-2.
  • the temperature of the reduction reaction is 50°C-80°C, and the reduction time is 8h-15h.
  • the interlayer spacing of the graphene oxide layer is
  • the interlayer spacing of the graphene oxide layer is
  • the pore diameters of the first porous substrate and the second porous substrate are both 0.1 ⁇ m-1 ⁇ m; the materials of the first porous substrate and the second porous substrate are both Includes cellulose acetate, polyethylene terephthalate, nylon, porous alumina or polyvinylidene fluoride.
  • a step of forming a first adhesive layer covering the first porous substrate is also included; During the suction filtration process, reduced graphene oxide is deposited on the surface of the first adhesive layer.
  • the first adhesive layer is a polydopamine layer; the step of forming the polydopamine layer includes: preparing a dopamine solution, the dopamine solution includes trishydroxymethylaminomethane-hydrochloric acid solution and dopamine hydrochloride, so The pH of the dopamine solution is 8-8.5; the first porous substrate is immersed in the dopamine solution to form a coating that coats the third porous substrate. A polydopamine layer on a porous substrate.
  • the time of the impregnation treatment is 1h-5h, and the temperature of the impregnation treatment is 20°C-30°C.
  • the step of preparing the dopamine solution includes: adding dopamine hydrochloride into the trishydroxymethylaminomethane-hydrochloric acid solution; wherein the concentration of the trishydroxymethylaminomethane-hydrochloric acid solution is 0.1mmol/L-5mmol/L. ; The concentration of dopamine hydrochloride in the dopamine solution is 0.1g/L-1g/L.
  • the method before arranging a second porous substrate on the side of the graphene oxide layer facing away from the first porous substrate, the method further includes forming a second bond covering the second porous substrate.
  • the step of layering after arranging the second porous substrate on the side of the graphene oxide layer facing away from the first porous substrate, one side surface of the graphene oxide layer is bonded to the second adhesive layer. Layer bonding.
  • the graphene oxide layer is dried at a temperature of 25°C-35°C and for a time of 24h-48h.
  • the concentration of graphene oxide in the prepared graphene oxide dispersion is 0.1g/L-2g/L; the dosage of the graphene oxide dispersion in the suction filtration step is 1mL-5mL; Before suction filtration of the graphene oxide dispersion, a step of diluting the graphene oxide dispersion 10 to 20 times is also included.
  • the steps for preparing the graphene oxide dispersion include: mixing concentrated sulfuric acid, potassium persulfate, phosphorus pentoxide and graphite powder evenly, and reacting at a temperature of 78°C-85°C for 3h-6h; after the reaction is completed, reduce the temperature. to the temperature range of 25°C-35°C and sequentially dilute, filter and wash, wash until neutral and then dry to obtain graphite pre-oxide;
  • the mass ratio of potassium persulfate, phosphorus pentoxide and graphite powder is (5-15): (5-15): (3-6), and 5g -15g potassium persulfate is mixed with 30mL-100mL concentrated sulfuric acid; in the step of preparing graphite oxide, the mass ratio of graphite pre-oxide, potassium permanganate and sodium nitrate is (2-6): (10-38) (2-6), and 2g-6g graphite preoxide is mixed with 100mL ⁇ 300mL concentrated sulfuric acid, and the corresponding dilution water consumption of 3g-6g graphite preoxide is 100mL-300mL.
  • the mesh number of the graphite powder is 100 mesh to 300 mesh.
  • the drying temperature is 40°C-70°C and the time is 12h- 24h.
  • the mass fraction of hydrogen peroxide is 30wt%-35wt%.
  • the centrifugation speed is 2000rpm-5000rpm, and the centrifugation time is 5min-20min.
  • This application also provides a nanofiltration composite membrane, which is prepared by using the above preparation method of the nanofiltration composite membrane.
  • This application also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 olefin production waste liquid.
  • using the nanofiltration composite membrane to treat CO 2 olefin production waste liquid includes the following steps: fixing the nanofiltration composite membrane on a porous substrate of a separation device; CO 2 olefin production waste liquid enters the separation device, and the waste liquid is Membrane separation occurs when the liquid flows through the nanofiltration composite membrane, and purified water is obtained.
  • the pressure within the separation device is 0.1MPa-10MPa.
  • the preparation method of the nanofiltration composite membrane provided in this application uses tannic acid to reduce graphene oxide. Since tannic acid has weak reducibility, the content of the graphene oxide surface can be controlled by controlling the amount of tannic acid added. The degree of reduction of oxygen functional groups can be used to control the interlayer spacing of the graphene oxide layer, so that the graphene oxide layer can be used for screening molecules or ions of different sizes, and the separation ability of the nanofiltration composite membrane can be controlled. .
  • a small amount of tannic acid can partially reduce the oxygen-containing functional groups on the surface of graphene oxide, and as the amount of tannic acid added increases, more and more oxygen-containing functional groups on the surface of graphene oxide are reduced and removed.
  • the interlayer spacing of the graphene oxide layer gradually shrinks; when the amount of tannic acid added increases to a certain extent, all the oxygen-containing functional groups on the surface of graphene oxide are reduced, and at this time, the interlayer spacing of the graphene oxide layer is the smallest; when the graphene oxide layer is When the oxygen-containing functional groups on the surface of graphene are partially reduced, the interlayer spacing of the graphene oxide layer is moderate, taking into account excellent separation effect and permeability.
  • the graphene oxide layer is located between the first porous substrate and the second porous substrate, which improves the structural stability of the graphene oxide layer without affecting the separation function of the graphene oxide layer.
  • tannic acid is green and environmentally friendly and will not cause harm to the environment.
  • the mass ratio of tannic acid to graphene oxide is 0.1-2, realizing the graphene oxide surface Partial reduction of oxygen-containing functional groups.
  • the interlayer spacing of graphene oxide is moderate, which can have both good separation effect and permeability.
  • a first adhesive layer is formed on the surface of the first porous substrate, and the reduced graphene oxide is deposited on the surface of the first adhesive layer. That is, the graphene oxide layer is fixed on the first adhesive layer through the first adhesive layer.
  • the porous substrate surface improves the structural stability of the nanofiltration composite membrane.
  • the second porous substrate is A second adhesive layer is formed on the surface of the material, so that one side surface of the graphene oxide layer is bonded to the second adhesive layer, which is beneficial to improving the structural stability of the nanofiltration composite membrane.
  • the nanofiltration composite membrane provided in this application uses tannic acid to reduce graphene oxide.
  • the degree of reduction of oxygen-containing functional groups on the surface of graphene oxide can be controlled, thereby achieving reduction of graphene oxide.
  • Controlling the interlayer spacing of the membrane enables the nanofiltration composite membrane to be used for screening molecules or ions of different sizes.
  • the graphene oxide layer is located between the first porous substrate and the second porous substrate, which improves the structural stability of the graphene oxide layer without affecting the separation function of the graphene oxide layer.
  • the application of the nanofiltration composite membrane provided by this application in the treatment of CO 2 olefin production waste liquid.
  • the water molecules in the waste liquid produced by CO 2 hydrogenation to synthesize low-carbon olefins can penetrate the graphene oxide layer, and the waste liquid Long-chain C 5 + hydrocarbons, acetic acid and catalyst particles in the liquid cannot penetrate the graphene oxide layer, thereby achieving efficient separation of waste liquid.
  • the water after membrane separation treatment through the nanofiltration composite membrane has a low salt content and can be used as circulating water in the carbon dioxide to olefin production process.
  • Figure 1 is a schematic structural diagram of the nanofiltration composite membrane provided by the embodiment of the present application.
  • Figure 2 is a scanning electron microscope image of the nanofiltration composite membrane prepared in Example 1;
  • Figure 3 is the Raman spectrum of the graphene oxide layer prepared in Example 1, Example 3, Example 5 and Comparative Example 1;
  • this embodiment provides a nanofiltration composite membrane, which includes a stacked first porous substrate 2, a first adhesive layer 4, a graphene oxide layer 1, a second adhesive layer 5 and Second porous substrate 3.
  • Its preparation method includes the following steps:
  • Pretreatment of the first porous substrate and the second porous substrate prepare 500 mL of tris-hydroxymethylaminomethane-hydrochloric acid solution (abbreviated as Tris-hydrochloric acid buffer) with a concentration of 1 mmol/L, and adjust the Tris -The pH of the hydrochloric acid buffer is 8.5; add 0.5g dopamine hydrochloride to the Tris-hydrochloric acid buffer, stir and dissolve to obtain a dopamine solution, the concentration of dopamine hydrochloride in the dopamine solution is 1g/L; then add the first porous substrate and The second porous substrate is soaked in a dopamine solution at 30°C for 1 hour, so that the first porous substrate and the second porous substrate are evenly coated with polydopamine.
  • the first porous substrate and the second porous substrate The materials are all cellulose acetate, with a pore size of 0.5 ⁇ m;
  • a second porous substrate is provided on the side of the graphene oxide layer facing away from the first porous substrate. After the nanofiltration composite membrane provided in this embodiment is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This embodiment also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 olefin production waste liquid.
  • using the nanofiltration composite membrane to treat CO 2 olefin production waste liquid includes the following steps: fixing the nanofiltration composite membrane on the stainless steel porous substrate of the stainless steel separation device through a gasket.
  • the condensed carbon dioxide olefin production waste liquid is passed into the separation device, and the pressure in the separation device is controlled to 0.2MPa.
  • the pressure in the separation device is controlled to 0.2MPa.
  • purified water is obtained.
  • the purified water can be returned to the boiler and stripper for recycling.
  • This embodiment provides a nanofiltration composite membrane.
  • the difference between the preparation method of the nanofiltration composite membrane provided in Example 1 is that in the reduction step of graphene oxide, 3 mg of tannin is added to 15 mL of graphene oxide dispersion. acid; the material of the first porous substrate is polyethylene terephthalate. After the nanofiltration composite membrane provided in this embodiment is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This embodiment also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 to olefin waste liquid, which is the same as the steps for treating CO 2 to olefin waste liquid provided in Example 1.
  • This embodiment provides a nanofiltration composite membrane.
  • the difference between the preparation method of the nanofiltration composite membrane provided in Example 1 is that in the reduction step of graphene oxide, 3 mg of tannin is added to 9 mL of graphene oxide dispersion. acid; the material of the first porous substrate is polyethylene terephthalate. After the nanofiltration composite membrane provided in this embodiment is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This embodiment also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 to olefin waste liquid, which is the same as the steps for treating CO 2 to olefin waste liquid provided in Example 1.
  • This embodiment provides a nanofiltration composite membrane.
  • the difference between the preparation method of the nanofiltration composite membrane provided in Example 1 is that in the reduction step of graphene oxide, 3 mg of tannin is added to 6 mL of graphene oxide dispersion. acid; the material of the first porous substrate is polyethylene terephthalate. After the nanofiltration composite membrane provided in this embodiment is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This embodiment also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 to olefin waste liquid, which is the same as the steps for treating CO 2 to olefin waste liquid provided in Example 1.
  • This embodiment provides a nanofiltration composite membrane.
  • the difference between the preparation method of the nanofiltration composite membrane provided in Example 1 is that in the reduction step of graphene oxide, 3 mg of tannin is added to 3 mL of graphene oxide dispersion. acid; the material of the first porous substrate is polyethylene terephthalate. After the nanofiltration composite membrane provided in this embodiment is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This embodiment also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 to olefin waste liquid, which is the same as the steps for treating CO 2 to olefin waste liquid provided in Example 1.
  • This embodiment provides a nanofiltration composite membrane.
  • the difference between the preparation method of the nanofiltration composite membrane provided in Example 1 is that in the reduction step of graphene oxide, 6 mg of tannin is added to 3 mL of graphene oxide dispersion. Acid, react in a water bath at 70°C for 15 hours; the material of the first porous substrate is polyethylene terephthalate. After the nanofiltration composite membrane provided in this embodiment is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This embodiment also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 to olefin waste liquid, which is the same as the steps for treating CO 2 to olefin waste liquid provided in Example 1.
  • This embodiment provides a nanofiltration composite membrane.
  • the difference between the preparation method of the nanofiltration composite membrane provided in Example 1 is that in the reduction step of graphene oxide, 9 mg of tannin is added to 3 mL of graphene oxide dispersion. Acid, react in a water bath at 70°C for 15 hours; the material of the first porous substrate is polyethylene terephthalate.
  • This embodiment provides the After the filter composite membrane is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This embodiment also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 to olefin waste liquid, which is the same as the steps for treating CO 2 to olefin waste liquid provided in Example 1.
  • This embodiment provides a nanofiltration composite membrane.
  • the difference between the preparation method of the nanofiltration composite membrane provided in Example 1 is that in the reduction step of graphene oxide, 15 mg of tannin is added to 3 mL of graphene oxide dispersion. Acid, react in a water bath at 70°C for 15 hours; the material of the first porous substrate is polyethylene terephthalate. After the nanofiltration composite membrane provided in this embodiment is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This embodiment also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 to olefin waste liquid, which is the same as the steps for treating CO 2 to olefin waste liquid provided in Example 1.
  • This embodiment provides a nanofiltration composite membrane.
  • the difference between the preparation method of the nanofiltration composite membrane provided in Example 1 is that in the reduction step of graphene oxide, 1 mg of tannin is added to 30 mL of graphene oxide dispersion. Acid, react in a water bath at 70°C for 15 hours; the material of the first porous substrate is polyethylene terephthalate. After the nanofiltration composite membrane provided in this embodiment is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This embodiment also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 to olefin waste liquid, which is the same as the steps for treating CO 2 to olefin waste liquid provided in Example 1.
  • This embodiment provides a nanofiltration composite membrane, which is different from the preparation method of the nanofiltration composite membrane provided in Example 1 in that the materials of the first porous substrate and the second porous substrate are both polyvinylidene fluoride. , the first porous substrate and the second porous substrate are not pre-treated, that is, the surface of the first porous substrate is not covered with the first adhesive layer, and the surface of the second porous substrate is not coated with the second adhesive layer. layering. After the nanofiltration composite membrane provided in this embodiment is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This embodiment also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 to olefin waste liquid, which is the same as the steps for treating CO 2 to olefin waste liquid provided in Example 1.
  • This embodiment provides a nanofiltration composite membrane, and its preparation method includes the following steps:
  • Pretreatment of the first porous substrate and the second porous substrate prepare 500 mL of tris-hydroxymethylaminomethane-hydrochloric acid solution (abbreviated as Tris-hydrochloric acid buffer) with a concentration of 5 mmol/L, and adjust the Tris -The pH of the hydrochloric acid buffer is 8; add 0.5g dopamine hydrochloride to the Tris-hydrochloric acid buffer, stir and dissolve to obtain a dopamine solution; then put the first porous substrate and the second porous substrate into the dopamine solution 25 Soak at °C for 2.5 hours, so that the first porous substrate and the second porous substrate are evenly coated with polydopamine.
  • the materials of the first porous substrate and the second porous substrate are both nylon, and the pore diameter is 0.1 ⁇ m;
  • a second porous substrate is provided on the side of the graphene oxide layer facing away from the first porous substrate. After the nanofiltration composite membrane provided in this embodiment is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This embodiment also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 to olefin waste liquid.
  • the difference between it and the step of treating CO 2 to olefin waste liquid provided in Example 1 is that: during the membrane separation process, the separation device The pressure is 0.1MPa.
  • the results show that the nanofiltration composite membrane has an interception rate of 98% for C 5 + in the CO 2 olefin production waste liquid, and the water flux reaches 38L m -2 h -1 bar -1 , reducing the chemical needs of the CO 2 olefin production waste liquid.
  • the oxygen COD is reduced to less than 100mg/L.
  • This embodiment provides a nanofiltration composite membrane, and its preparation method includes the following steps:
  • Pretreatment of the first porous substrate and the second porous substrate prepare 500 mL of tris-hydroxymethylaminomethane-hydrochloric acid solution (abbreviated as Tris-hydrochloric acid buffer) with a concentration of 0.1 mmol/L, and adjust The pH of Tris-HCl buffer is 8.5; add 0.05g dopamine hydrochloride to Tris-HCl buffer, stir and dissolve to obtain a dopamine solution; then put the first porous substrate and the second porous substrate into the dopamine solution Soak at 20°C for 5 hours to make the first porous substrate and the second porous substrate evenly coated with polydopamine.
  • the material of the first porous substrate and the second porous substrate is porous alumina, with a pore diameter of 1 ⁇ m. ;
  • a second porous substrate is provided on the side of the graphene oxide layer facing away from the first porous substrate. After the nanofiltration composite membrane provided in this embodiment is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This embodiment also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 to olefin waste liquid.
  • the difference between it and the step of treating CO 2 to olefin waste liquid provided in Example 1 is that: during the membrane separation process, the separation device The pressure is 0.1MPa. Knot The results show that the nanofiltration composite membrane has an interception rate of 99.9% for C 5 + in the CO 2 olefin production waste liquid, and the water flux reaches 22L m -2 h - 1 bar -1 , reducing the chemical needs of the CO 2 olefin production waste liquid.
  • the oxygen COD is reduced to less than 100mg/L.
  • This comparative example provides a nanofiltration composite membrane.
  • the difference from the preparation method of the nanofiltration composite membrane provided in Example 1 is that graphene oxide does not undergo reduction treatment. After the nanofiltration composite membrane provided in this comparative example is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This comparative example also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 to olefin waste liquid, which is the same as the steps for treating CO 2 to olefin waste liquid provided in Example 1.
  • This comparative example provides a nanofiltration composite membrane.
  • the difference between the preparation method of the nanofiltration composite membrane provided in Example 1 is that hydrazine hydrate is used to reduce graphene oxide. Specifically, 30 mL of graphene oxide dispersion is taken and the pH is adjusted. When the value reaches 9, add 1 mL of 85% hydrazine hydrate to the dispersion, stir and react in a 95°C water bath for 1 hour. The product was filtered, washed with absolute ethanol several times, washed with a large amount of deionized water, and dried at 25°C for 48 hours. After the nanofiltration composite membrane provided in this comparative example is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This comparative example also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 to olefin waste liquid, which is the same as the steps for treating CO 2 to olefin waste liquid provided in Example 1.
  • This comparative example provides a nanofiltration composite membrane.
  • the difference between the preparation method of the nanofiltration composite membrane provided in Example 1 is that hydriodic acid is used to reduce graphene oxide. Specifically, 30 mL of graphene oxide dispersion is added. 3 mL hydriodic acid, stir and react in a 100°C water bath for 1 hour. Wash several times with absolute ethanol, then wash with a large amount of deionized water, and dry at 25°C for 48 hours. After the nanofiltration composite membrane provided in this comparative example is soaked in water, the interlayer spacing of the graphene oxide layer is
  • This comparative example also provides the application of the above-mentioned nanofiltration composite membrane in treating CO 2 to olefin waste liquid, which is the same as the steps for treating CO 2 to olefin waste liquid provided in Example 1.
  • the purified water prepared in Examples 1-12 and Comparative Examples 1-3 was subjected to UV analysis, chemical oxygen demand (COD), inductively coupled plasma (ICP) and other tests. The test results are shown in Table 1 and Table 2.
  • tannic acid can achieve partial reduction of graphene oxide.
  • the addition of tannic acid When the amount increases to a certain extent, all the oxygen-containing functional groups on the surface of graphene oxide are reduced, and the interlayer spacing of partially reduced graphene oxide is greater than that of fully reduced graphene oxide, and a small amount of hydrazine hydrate and hydriodic acid can suffice. All oxygen-containing functional groups on the surface of graphene oxide are reduced. It can be seen that tannic acid can achieve controllable reduction of graphene oxide, and graphene oxide with different interlayer spacing is suitable for screening molecules or ions of different sizes.
  • Example 10 is graphene oxide without an adhesive layer, and its separation effect is the same as that of Example 1, indicating that the adhesive layer will not affect the separation performance.

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Abstract

一种纳滤复合膜及其制备方法。制备方法包括：配制氧化石墨烯分散液；向氧化石墨烯分散液中加入单宁酸以进行还原反应，使氧化石墨烯分散液中的氧化石墨烯实现至少部分还原；对氧化石墨烯分散液进行抽滤，使还原后的氧化石墨烯沉积在第一多孔基材上，得到氧化石墨烯层；对氧化石墨烯层进行干燥；在氧化石墨烯层背离第一多孔基材的一侧设置第二多孔基材。通过控制单宁酸的添加量实现对氧化石墨烯层的层间距的控制，以使氧化石墨烯层能够用于不同尺寸的分子或离子的筛分。

Description

一种纳滤复合膜及其制备方法
相关申请的交叉引用
本申请要求在2022年3月28日提交中国专利局、申请号为202210315681.5、发明名称为“一种纳滤复合膜及其制备方法”的中国专利申请的优先权，其全部内容通过引用的方式并入本文中。
技术领域
本申请涉及膜分离技术领域，具体涉及一种纳滤复合膜及其制备方法。
背景技术
过度开采和使用化石能源所带来的能源危机和环境问题，已经成为人类亟待解决的难题之一。为此，各国科学家呼吁从源头上降低CO2的排放量或者实现CO2的资源化利用。实现CO2的资源化利用，即将其转化为具有高附加值的化学品，如，通过CO2加氢合成低碳烯烃，不仅实现了CO2的直接固化，还生产乙烯、丙烯和丁二烯等重要的化工原料。CO2加氢合成低碳烯烃的过程中，会产生大量含有盐、油及催化剂颗粒的废液。膜分离法是一种新兴发展的分离技术，目前已经被广泛地用于工业和城市废液处理、有机污染物去除、重金属离子去除、超纯水制备以及气体分离等领域。膜分离工艺具有能耗低、选择性高、无相变、设备简便灵活、不产生二次污染等优点，非常适合应用于处理CO2合成低碳烯烃过程产生的废液。
氧化石墨烯膜可视为具有二维纳米通道的毛细网络，通过调控氧化石墨烯纳米片层之间的层间距，可以实现对不同尺寸的分子或离子的筛分。氧化石墨烯表面含有大量亲水性的含氧官能团，含氧官能团易吸附水分子而发生溶胀效应，导致氧化石墨烯纳米片层之间的层间距迅速增大，从而降低氧化石墨烯膜的分离效果和结构稳定性。为此，通常采用水合肼或氢碘酸对氧化石墨烯进行还原，以提高氧化石墨烯膜的分离效果和结构稳定性。
然而，由于水合肼或氢碘酸的还原能力过大，使用很少的水合肼或氢碘酸就能够使氧 化石墨烯表面的含氧官能团全部还原，这使还原后的氧化石墨烯层间距为一固定值，其所能筛分的分子或离子的尺寸也为一固定值，无法实现对不同尺寸的分子或离子的筛分。
发明内容
因此，本申请要解决的技术问题在于克服现有氧化石墨烯膜无法实现对不同尺寸的分子或离子的筛分的缺陷，从而提供一种纳滤复合膜及其制备方法。
本申请提供一种纳滤复合膜的制备方法，包括：配制氧化石墨烯分散液；向所述氧化石墨烯分散液中加入单宁酸以进行还原反应，使所述氧化石墨烯分散液中的氧化石墨烯实现至少部分还原；对所述氧化石墨烯分散液进行抽滤，使还原后的氧化石墨烯沉积在第一多孔基材上，得到氧化石墨烯层；对所述氧化石墨烯层进行干燥；在所述氧化石墨烯层背离所述第一多孔基材的一侧设置第二多孔基材。
可选的，向所述氧化石墨烯分散液中加入单宁酸后，单宁酸与氧化石墨烯的质量比为0.03-5。
可选的，向所述氧化石墨烯分散液中加入单宁酸后，单宁酸与氧化石墨烯的质量比为0.1-2。
可选的，所述还原反应的温度为50℃-80℃，还原的时间为8h-15h。
可选的，所述氧化石墨烯层的层间距为
可选的，所述氧化石墨烯层的层间距为
可选的，所述第一多孔基材和所述第二多孔基材的孔径均为0.1μm-1μm；所述第一多孔基材和所述第二多孔基材的材料均包括乙酸纤维素、聚对苯二甲酸乙二醇酯、尼龙、多孔氧化铝或聚偏氟乙烯。
可选的，在对所述氧化石墨烯分散液进行抽滤之前，还包括形成包覆所述第一多孔基材的第一粘结层的步骤；在对所述氧化石墨烯分散液进行抽滤的过程中，还原的氧化石墨烯沉积在所述第一粘结层表面。
可选的，所述第一粘结层为聚多巴胺层；形成所述聚多巴胺层的步骤包括：配制多巴胺溶液，所述多巴胺溶液中包括三羟甲基氨基甲烷-盐酸溶液和盐酸多巴胺，所述多巴胺溶液的PH为8-8.5；所述第一多孔基材在所述多巴胺溶液中进行浸渍处理，形成包覆所述第 一多孔基材的聚多巴胺层。
可选的，所述浸渍处理的时间为1h-5h，所述浸渍处理的温度为20℃-30℃。
可选的，配制所述多巴胺溶液的步骤包括：将盐酸多巴胺加入三羟甲基氨基甲烷-盐酸溶液中；其中，三羟甲基氨基甲烷-盐酸溶液的浓度为0.1mmol/L-5mmol/L；所述多巴胺溶液中盐酸多巴胺的浓度为0.1g/L-1g/L。
可选的，在所述氧化石墨烯层背离所述第一多孔基材的一侧设置第二多孔基材之前，还包括形成包覆所述第二多孔基材的第二粘结层的步骤；在所述氧化石墨烯层背离所述第一多孔基材的一侧设置所述第二多孔基材之后，所述氧化石墨烯层的一侧表面与所述第二粘结层粘结。
可选的，对所述氧化石墨烯层进行干燥的温度为25℃-35℃，时间为24h-48h。
可选的，配制的所述氧化石墨烯分散液中氧化石墨烯的浓度为0.1g/L-2g/L；所述抽滤步骤中所述氧化石墨烯分散液的用量为1mL-5mL；在对所述氧化石墨烯分散液进行抽滤之前，还包括将所述氧化石墨烯分散液稀释10倍-20倍的步骤。
可选的，配制氧化石墨烯分散液的步骤包括：将浓硫酸、过硫酸钾、五氧化二磷和石墨粉混合均匀，在78℃-85℃的温度下反应3h-6h；反应结束后降至25℃-35℃的温度范围内并依次进行稀释、抽滤和洗涤，洗涤至中性后进行干燥，得到石墨预氧化物；
将浓硫酸、石墨预氧化物和高锰酸钾在5℃-20℃的温度范围内混合均匀，随后加入硝酸钠，在30℃-35℃的温度下反应1h-3h；随后加入水稀释，并在30℃-35℃的温度下继续反应1h-3h；随后加入双氧水终止反应，得到石墨氧化物；对石墨氧化物依次进行酸洗和水洗，待洗涤至中性后将石墨氧化物超声分散到水中，随后离心去除未反应的石墨片层，得到氧化石墨烯分散液。
可选的，在制备石墨预氧化物的步骤中，过硫酸钾、五氧化二磷和石墨粉的质量之比为(5-15)：(5-15)：(3-6)，且5g-15g过硫酸钾与30mL-100mL浓硫酸混合；在制备石墨氧化物的步骤中，石墨预氧化物、高锰酸钾和硝酸钠的质量之比为(2-6)：(10-38)：(2-6)，且2g-6g石墨预氧化物与100mL～300mL浓硫酸混合，3g-6g石墨预氧化物对应的稀释用水量为100mL-300mL。
可选的，在制备石墨预氧化物的步骤中，所述石墨粉的目数为100目-300目。
可选的，在制备石墨预氧化物的步骤中，所述干燥的温度为40℃-70℃，时间为12h- 24h。
可选的，在制备石墨氧化物的步骤中，所述双氧水的质量分数为30wt％-35wt％。
可选的，采用浓度为5vol％-20vol％的稀盐酸溶液对石墨氧化物进行酸洗。
可选的，所述离心的转速为2000rpm-5000rpm，时间为5min-20min。
本申请还提供一种纳滤复合膜，采用上述纳滤复合膜的制备方法制得。
本申请还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用。
可选的，采用所述纳滤复合膜处理CO2制烯烃废液包括以下步骤：将所述纳滤复合膜固定在分离装置的多孔衬底上；CO2制烯烃废液进入分离装置，废液流经所述纳滤复合膜时发生膜分离，得到净化水。
可选的，所述膜分离过程中，分离装置内的压力为0.1MPa-10MPa。
本申请技术方案，具有如下优点：
1.本申请提供的纳滤复合膜的制备方法，采用单宁酸对氧化石墨烯进行还原，由于单宁酸的还原性弱，通过控制单宁酸的添加量能够控制氧化石墨烯表面的含氧官能团的还原程度，从而实现对氧化石墨烯层的层间距的控制，以使氧化石墨烯层能够用于不同尺寸的分子或离子的筛分，实现了对纳滤复合膜的分离能力的控制。
具体的，少量的单宁酸能够实现氧化石墨烯表面的含氧官能团的部分还原，且随着单宁酸添加量的增大，氧化石墨烯表面越来越多的含氧官能团被还原去除，从而使氧化石墨烯层的层间距逐渐缩小；单宁酸的添加量增大至一定程度时，氧化石墨烯表面的含氧官能团全部还原，此时氧化石墨烯层的层间距最小；当氧化石墨烯表面的含氧官能团被部分还原时，氧化石墨烯层的层间距适中，兼顾优良的分离效果和渗透性能。
同时，氧化石墨烯层位于第一多孔基材和第二多孔基材之间，在不影响氧化石墨烯层的分离功能的基础上，提高了氧化石墨烯层的结构稳定性。此外，单宁酸绿色环保，不会对环境造成危害。
2.本申请提供的纳滤复合膜的制备方法，向所述氧化石墨烯分散液中加入单宁酸后，单宁酸与氧化石墨烯的质量比为0.1-2，实现了氧化石墨烯表面的含氧官能团的部分还原，此时氧化石墨烯的层间距适中，能够兼具良好的分离效果和渗透性能。
3.本申请提供的纳滤复合膜的制备方法，在对所述氧化石墨烯分散液进行抽滤之前，在 所述第一多孔基材表面形成第一粘结层，使还原后的氧化石墨烯沉积在所述第一粘结层表面，即，氧化石墨烯层通过第一粘结层固定在第一多孔基材表面，提高了纳滤复合膜的结构稳定性。
4.本申请提供的纳滤复合膜的制备方法，在所述氧化石墨烯层背离所述第一多孔基材的一侧设置第二多孔基材之前，在所述第二多孔基材表面形成第二粘结层，使所述氧化石墨烯层的一侧表面与所述第二粘结层粘结，有利于提高纳滤复合膜的结构稳定性。
5.本申请提供的纳滤复合膜，采用单宁酸对氧化石墨烯进行还原，通过控制单宁酸的添加量能够控制氧化石墨烯表面的含氧官能团的还原程度，从而实现对氧化石墨烯膜的层间距的控制，进而使纳滤复合膜能够用于不同尺寸的分子或离子的筛分。同时，氧化石墨烯层位于第一多孔基材和第二多孔基材之间，在不影响氧化石墨烯层的分离功能的基础上，提高了氧化石墨烯层的结构稳定性。
6.本申请提供的纳滤复合膜在处理CO2制烯烃废液中的应用，CO2加氢合成低碳烯烃产生的废液中的水分子能够透过所述氧化石墨烯层，而废液中的长链C5 +烃类、乙酸和催化剂颗粒等不能够透过所述氧化石墨烯层，从而实现了废液的高效分离。通过所述纳滤复合膜进行膜分离处理后的水含盐量低，可以作为循环水应用于二氧化碳制烯烃工艺流程中。
附图说明
为了更清楚地说明本申请具体实施方式或现有技术中的技术方案，下面将对具体实施方式或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本申请的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本申请实施例的提供的纳滤复合膜的结构示意图；
图2为实施例1制备得到的纳滤复合膜的扫描电镜图；
图3为实施例1、实施例3、实施例5和对比例1制备得到的氧化石墨烯层的拉曼图谱；
附图标记说明：
1-氧化石墨烯层；2-第一多孔基材；3-第二多孔基材；4-第一粘结层；5-第二粘结层。
具体实施方式
下面将结合附图对本申请的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
在本申请的描述中，需要说明的是，术语“上”、“下”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。此外，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性。
实施例1
如图1所示，本实施例提供一种纳滤复合膜，其包括层叠设置的第一多孔基材2、第一粘结层4、氧化石墨烯层1、第二粘结层5和第二多孔基材3。其制备方法包括以下步骤：
(1)配制氧化石墨烯分散液：
将50mL浓硫酸、8.0g过硫酸钾、8.0g五氧化二磷依次加入圆底烧瓶中，剧烈搅拌以得到澄清溶液；随后，水浴加热至80℃后加入4.0g的200目石墨粉并80℃反应5h；反应结束后冷却至25℃-35℃的范围，加入200mL水缓慢稀释；随后，对反应物进行抽滤和洗涤，洗涤至中性后在60℃干燥12h，得到石墨预氧化物；
将140mL浓硫酸加入到圆底烧瓶中，在搅拌条件下加入3.0g石墨预氧化物；随后少量多次加入18.0g高锰酸钾，搅拌进行反应，严格控制温度在5℃-20℃的温度范围内；随后加入3.0g硝酸钠，在35℃条件下水浴反应2h；随后加入300mL水稀释，在35℃的水浴中继续反应2h；随后加入10mL质量分数为35wt％的双氧水，待棕色反应液突变为亮黄色，获得石墨氧化物；
将石墨氧化物中加入10vol％稀盐酸中充分搅拌，再用水洗涤至中性；将石墨氧化物超声分散到300mL水中，然后在4000rpm条件下离心10min去除未反应的石墨片层，获得浓度为1g/L稳定分散的氧化石墨烯分散液。
(2)氧化石墨烯的还原：向30mL氧化石墨烯分散液中加入3mg单宁酸，再用200mL水稀释，在70℃条件下水浴反应10h。
(3)第一多孔基材和第二多孔基材的预处理：配制500mL浓度为1mmol/L的三羟甲基氨基甲烷-盐酸溶液(简写为Tris-盐酸缓冲液)，并调节Tris-盐酸缓冲液的pH为8.5；向Tris-盐酸缓冲液中加入0.5g盐酸多巴胺，并搅拌溶解得到多巴胺溶液，多巴胺溶液中盐酸多巴胺的浓度为1g/L；然后将第一多孔基材和第二多孔基材放入多巴胺溶液中30℃浸泡1h，使第一多孔基材和第二多孔基材均匀包覆有聚多巴胺，第一多孔基材和第二多孔基材的材料均为乙酸纤维素，孔径为0.5μm；
(4)氧化石墨烯层的制备：将3mL还原的氧化石墨烯分散液用水稀释10倍，随后采用真空抽滤法使还原的氧化石墨烯沉积在第一多孔基材上，25℃干燥48h；图2表示为还原的氧化石墨烯膜扫描电镜图谱。
(5)纳滤复合膜的组装：在所述氧化石墨烯层背离所述第一多孔基材的一侧设置第二多孔基材。本实施例提供的纳滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本实施例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用。
具体的，采用所述纳滤复合膜处理CO2制烯烃废液包括以下步骤：通过垫圈将纳滤复合膜固定在不锈钢分离装置的不诱钢多孔衬底上。将冷凝的二氧化碳制烯烃废液通入分离装置，并控制分离装置内的压力为0.2MPa，废液流经所述纳滤复合膜时发生膜分离，得到净化水。净化水可以返回锅炉、汽提塔，进行循环利用。
实施例2
本实施例提供一种纳滤复合膜，其与实施例1提供的纳滤复合膜的制备方法的区别在于：在氧化石墨烯的还原步骤中，向15mL氧化石墨烯分散液中加入3mg单宁酸；第一多孔基材的材料为聚对苯二甲酸乙二醇酯。本实施例提供的纳滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本实施例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用，其与实施例1提供的处理CO2制烯烃废液的步骤相同。
实施例3
本实施例提供一种纳滤复合膜，其与实施例1提供的纳滤复合膜的制备方法的区别在于：在氧化石墨烯的还原步骤中，向9mL氧化石墨烯分散液中加入3mg单宁酸；第一多孔基材的材料为聚对苯二甲酸乙二醇酯。本实施例提供的纳滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本实施例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用，其与实施例1提供的处理CO2制烯烃废液的步骤相同。
实施例4
本实施例提供一种纳滤复合膜，其与实施例1提供的纳滤复合膜的制备方法的区别在于：在氧化石墨烯的还原步骤中，向6mL氧化石墨烯分散液中加入3mg单宁酸；第一多孔基材的材料为聚对苯二甲酸乙二醇酯。本实施例提供的纳滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本实施例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用，其与实施例1提供的处理CO2制烯烃废液的步骤相同。
实施例5
本实施例提供一种纳滤复合膜，其与实施例1提供的纳滤复合膜的制备方法的区别在于：在氧化石墨烯的还原步骤中，向3mL氧化石墨烯分散液中加入3mg单宁酸；第一多孔基材的材料为聚对苯二甲酸乙二醇酯。本实施例提供的纳滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本实施例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用，其与实施例1提供的处理CO2制烯烃废液的步骤相同。
实施例6
本实施例提供一种纳滤复合膜，其与实施例1提供的纳滤复合膜的制备方法的区别在于：在氧化石墨烯的还原步骤中，向3mL氧化石墨烯分散液中加入6mg单宁酸，在70℃条件下水浴反应15h；第一多孔基材的材料为聚对苯二甲酸乙二醇酯。本实施例提供的纳滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本实施例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用，其与实施例1提供的处理CO2制烯烃废液的步骤相同。
实施例7
本实施例提供一种纳滤复合膜，其与实施例1提供的纳滤复合膜的制备方法的区别在于：在氧化石墨烯的还原步骤中，向3mL氧化石墨烯分散液中加入9mg单宁酸，在70℃条件下水浴反应15h；第一多孔基材的材料为聚对苯二甲酸乙二醇酯。本实施例提供的纳 滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本实施例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用，其与实施例1提供的处理CO2制烯烃废液的步骤相同。
实施例8
本实施例提供一种纳滤复合膜，其与实施例1提供的纳滤复合膜的制备方法的区别在于：在氧化石墨烯的还原步骤中，向3mL氧化石墨烯分散液中加入15mg单宁酸，在70℃条件下水浴反应15h；第一多孔基材的材料为聚对苯二甲酸乙二醇酯。本实施例提供的纳滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本实施例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用，其与实施例1提供的处理CO2制烯烃废液的步骤相同。
实施例9
本实施例提供一种纳滤复合膜，其与实施例1提供的纳滤复合膜的制备方法的区别在于：在氧化石墨烯的还原步骤中，向30mL氧化石墨烯分散液中加入1mg单宁酸，在70℃条件下水浴反应15h；第一多孔基材的材料为聚对苯二甲酸乙二醇酯。本实施例提供的纳滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本实施例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用，其与实施例1提供的处理CO2制烯烃废液的步骤相同。
实施例10
本实施例提供一种纳滤复合膜，其与实施例1提供的纳滤复合膜的制备方法的区别在于：第一多孔基材和第二多孔基材的材料均为聚偏氟乙烯，第一多孔基材和第二多孔基材不进行预处理，即，第一多孔基材表面不包覆第一粘结层，第二多孔基材表面不包覆第二粘结层。本实施例提供的纳滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本实施例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用，其与实施例1提供的处理CO2制烯烃废液的步骤相同。
实施例11
本实施例提供一种纳滤复合膜，其制备方法包括以下步骤：
(1)配制氧化石墨烯分散液：
将100mL浓硫酸、15.0g过硫酸钾、15.0g五氧化二磷依次加入圆底烧瓶中，剧烈搅拌以得到澄清溶液；随后，水浴加热至85℃后加入6.0g的100目石墨粉并85℃反应6h；反应结束后冷却至25℃-35℃的范围内，加入500mL水缓慢稀释；随后，对反应物进行抽滤和洗涤，洗涤至中性后在40℃干燥24h，得到石墨预氧化物；
将300mL浓硫酸加入到圆底烧瓶中，在搅拌条件下加入6.0g石墨预氧化物；随后少量多次加入38.0g高锰酸钾，搅拌进行反应，严格控制温度在5℃-20℃范围内；随后加入6.0g硝酸钠，在35℃条件下水浴反应1h；随后加入600mL水稀释，在35℃的水浴中继续反应1h；随后加入10mL质量分数为35wt％的双氧水，待棕色反应液突变为亮黄色，获得石墨氧化物；
将石墨氧化物中加入20vol％稀盐酸中充分搅拌，再用水洗涤至中性；将石墨氧化物超声分散到100mL水中，然后在5000rpm条件下离心5min去除未反应的石墨片层，获得浓度为2g/L稳定分散的氧化石墨烯分散液。
(2)氧化石墨烯的部分还原：向1mL氧化石墨烯分散液中加入5mg单宁酸，再用100mL水稀释，在80℃条件下水浴反应15h。
(3)第一多孔基材和第二多孔基材的预处理：配制500mL浓度为5mmol/L的三羟甲基氨基甲烷-盐酸溶液(简写为Tris-盐酸缓冲液)，并调节Tris-盐酸缓冲液的pH为8；向Tris-盐酸缓冲液中加入0.5g盐酸多巴胺，并搅拌溶解得到多巴胺溶液；然后将第一多孔基材和第二多孔基材放入多巴胺溶液中25℃浸泡2.5h，使第一多孔基材和第二多孔基材均匀包覆有聚多巴胺，第一多孔基材和第二多孔基材的材料均为尼龙，孔径为0.1μm；
(4)氧化石墨烯层的制备：将5mL部分还原的氧化石墨烯分散液用水稀释15倍，随后采用真空抽滤法使部分还原的氧化石墨烯沉积在第一多孔基材上，30℃干燥36h；
(5)纳滤复合膜的组装：在所述氧化石墨烯层背离所述第一多孔基材的一侧设置第二多孔基材。本实施例提供的纳滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本实施例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用，其与实施例1提供的处理CO2制烯烃废液的步骤的区别在于：膜分离过程中分离装置内的压力为0.1MPa。结果表明，纳滤复合膜对CO2制烯烃废液中C5 +的拦截率达到98％，水通量达到38L m-2h-1bar-1，将CO2制烯烃废液的化学需氧量COD降低至100mg/L以下。
实施例12
本实施例提供一种纳滤复合膜，其制备方法包括以下步骤：
(1)配制氧化石墨烯分散液：
将30mL浓硫酸、5.0g过硫酸钾、5.0g五氧化二磷依次加入圆底烧瓶中，剧烈搅拌以得到澄清溶液；随后，水浴加热至75℃后加入3.0g的300目石墨粉并78℃反应3h；反应结束后冷却至25℃-35℃的范围内，加入100mL水缓慢稀释；随后，对反应物进行抽滤和洗涤，洗涤至中性后在70℃干燥12h，得到石墨预氧化物；
将100mL浓硫酸加入到圆底烧瓶中，在搅拌条件下加入2.0g石墨预氧化物；随后少量多次加入10.0g高锰酸钾，搅拌进行反应，严格控制温度在5℃-20℃范围内；随后加入2.0g硝酸钠，在30℃条件下水浴反应3h；随后加入200mL水稀释，在30℃的水浴中继续反应3h；随后加入10mL质量分数为30wt％的双氧水，待棕色反应液突变为亮黄色，获得石墨氧化物；
将石墨氧化物中加入5vol％稀盐酸中充分搅拌，再用水洗涤至中性；将石墨氧化物超声分散到300mL水中，然后在2000rpm条件下离心20min去除未反应的石墨片层，获得浓度为0.1g/L稳定分散的氧化石墨烯分散液。
(2)氧化石墨烯的部分还原：向10mL氧化石墨烯分散液中加入1mg单宁酸，再用200mL水稀释，在50℃条件下水浴反应8h。
(3)第一多孔基材和第二多孔基材的预处理：配制500mL浓度为0.1mmol/L的三羟甲基氨基甲烷-盐酸溶液(简写为Tris-盐酸缓冲液)，并调节Tris-盐酸缓冲液的pH为8.5；向Tris-盐酸缓冲液中加入0.05g盐酸多巴胺，并搅拌溶解得到多巴胺溶液；然后将第一多孔基材和第二多孔基材放入多巴胺溶液中20℃浸泡5h，使第一多孔基材和第二多孔基材均匀包覆有聚多巴胺，第一多孔基材和第二多孔基材的材料均为多孔氧化铝，孔径为1μm；
(4)氧化石墨烯层的制备：将10mL部分还原的氧化石墨烯分散液用水稀释10倍，随后采用真空抽滤法使部分还原的氧化石墨烯沉积在第一多孔基材上，35℃干燥24h；
(5)纳滤复合膜的组装：在所述氧化石墨烯层背离所述第一多孔基材的一侧设置第二多孔基材。本实施例提供的纳滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本实施例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用，其与实施例1提供的处理CO2制烯烃废液的步骤的区别在于：膜分离过程中分离装置内的压力为0.1MPa。结 果表明，纳滤复合膜对CO2制烯烃废液中C5 +的拦截率达到99.9％，水通量达到22L m-2h- 1bar-1，将CO2制烯烃废液的化学需氧量COD降低至100mg/L以下。
对比例1
本对比例提供一种纳滤复合膜，其与实施例1提供的纳滤复合膜的制备方法的区别在于：氧化石墨烯不经过还原处理。本对比例提供的纳滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本对比例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用，其与实施例1提供的处理CO2制烯烃废液的步骤相同。
对比例2
本对比例提供一种纳滤复合膜，其与实施例1提供的纳滤复合膜的制备方法的区别在于：采用水合肼还原氧化石墨烯，具体的，取30mL氧化石墨烯分散液，调节pH值到9，向分散液中加入1mL 85％水合肼，95℃水浴中搅拌反应1h。将产物过滤，用无水乙醇洗涤数次，再用大量去离子水洗涤，25℃干燥48h。本对比例提供的纳滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本对比例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用，其与实施例1提供的处理CO2制烯烃废液的步骤相同。
对比例3
本对比例提供一种纳滤复合膜，其与实施例1提供的纳滤复合膜的制备方法的区别在于：采用氢碘酸还原氧化石墨烯，具体的，向30mL氧化石墨烯分散液中加入3mL氢碘酸，100℃水浴中搅拌反应1h。用无水乙醇洗涤数次，再用大量去离子水洗涤，25℃干燥48h。本对比例提供的纳滤复合膜在水中浸泡后，氧化石墨烯层的层间距为
本对比例还提供上述纳滤复合膜在处理CO2制烯烃废液中的应用，其与实施例1提供的处理CO2制烯烃废液的步骤相同。
试验例1
对实施例1、实施例3、实施例5和对比例1制备得到的氧化石墨烯层进行拉曼光谱分析，结果如图3所示。由图3可知，随着向所述氧化石墨烯分散液中的单宁酸添加量的增加，拉曼图谱中D峰和G峰的峰强比(ID/IG)逐步减小，说明氧化石墨烯的还原程度在逐 步增大。
试验例2
对实施例1-12和对比例1-3制得的净化水进行紫外分析、化学需氧量(COD)、电感耦合等离子体(ICP)等测试。测试结果如表1和表2所示。
表1
表2
实施例7-8以及对比例2-3中的氧化石墨烯被全部还原，实施例1-6以及实施例9-12中的氧化石墨烯被部分还原。
由表1和表2可知，少量的单宁酸能够实现的氧化石墨烯的部分还原，单宁酸的添加 量增大至一定程度时，氧化石墨烯表面的含氧官能团全部还原，部分还原的氧化石墨烯的层间距大于全部还原的氧化石墨烯的层间距，而少量的水合肼和氢碘酸即可使氧化石墨烯表面的含氧官能团全部还原。由此可见，单宁酸能够实现对氧化石墨烯的可控还原，且具有不同层间距的氧化石墨烯适用于不同尺寸的分子或离子的筛分。
由实施例1-8可知，随着氧化石墨烯的还原程度的增大，氧化石墨烯层的层间距逐渐减小，纳滤复合膜对CO2制烯烃废液的分离效果逐渐增大，而渗透性能逐步降低；当氧化石墨烯被全部还原后，继续增大单宁酸的添加量，纳滤复合膜的分离效果和渗透性能不发生变化。部分还原的氧化石墨烯能够兼具良好的分离效果和渗透性能，其中，实施例5提供的纳滤复合膜兼具最优的分离效果和渗透性能。
实施例10为不包覆粘结层的氧化石墨烯，其分离效果与实施例1相同，说明粘结层不会对分离性能产生影响。
显然，上述实施例仅仅是为清楚地说明所作的举例，而并非对实施方式的限定。对于所属领域的普通技术人员来说，在上述说明的基础上还可以做出其它不同形式的变化或变动。这里无需也无法对所有的实施方式予以穷举。而由此所引伸出的显而易见的变化或变动仍处于本发明创造的保护范围之中。

Claims (10)

  1. 一种纳滤复合膜的制备方法，其特征在于，包括：
    配制氧化石墨烯分散液；
    向所述氧化石墨烯分散液中加入单宁酸以进行还原反应，使所述氧化石墨烯分散液中的氧化石墨烯实现至少部分还原；
    对所述氧化石墨烯分散液进行抽滤，使还原后的氧化石墨烯沉积在第一多孔基材上，得到氧化石墨烯层；
    对所述氧化石墨烯层进行干燥；
    在所述氧化石墨烯层背离所述第一多孔基材的一侧设置第二多孔基材。
  2. 根据权利要求1所述的纳滤复合膜的制备方法，其特征在于，向所述氧化石墨烯分散液中加入单宁酸后，单宁酸与氧化石墨烯的质量比为0.03-5；
    优选的，向所述氧化石墨烯分散液中加入单宁酸后，单宁酸与氧化石墨烯的质量比为0.1-2。
  3. 根据权利要求1所述的纳滤复合膜的制备方法，其特征在于，所述氧化石墨烯层的层间距为
    优选的，所述氧化石墨烯层的层间距为
  4. 根据权利要求1所述的纳滤复合膜的制备方法，其特征在于，所述第一多孔基材和所述第二多孔基材的孔径均为0.1μm-1μm；
    所述第一多孔基材和所述第二多孔基材的材料均包括乙酸纤维素、聚对苯二甲酸乙二醇酯、尼龙、多孔氧化铝或聚偏氟乙烯。
  5. 根据权利要求1所述的纳滤复合膜的制备方法，其特征在于，在对所述氧化石墨烯分散液进行抽滤之前，还包括形成包覆所述第一多孔基材的第一粘结层的步骤；在对所述氧 化石墨烯分散液进行抽滤的过程中，还原的氧化石墨烯沉积在所述第一粘结层表面。
  6. 根据权利要求5所述的纳滤复合膜的制备方法，其特征在于，所述第一粘结层为聚多巴胺层；
    形成所述聚多巴胺层的步骤包括：配制多巴胺溶液，所述多巴胺溶液中包括三羟甲基氨基甲烷-盐酸溶液和盐酸多巴胺，所述多巴胺溶液的PH为8-8.5；所述第一多孔基材在所述多巴胺溶液中进行浸渍处理，形成包覆所述第一多孔基材的聚多巴胺层；
    优选的，所述浸渍处理的时间为1h-5h，所述浸渍处理的温度为20℃-30℃。
  7. 根据权利要求6所述的纳滤复合膜的制备方法，其特征在于，配制所述多巴胺溶液的步骤包括：将盐酸多巴胺加入三羟甲基氨基甲烷-盐酸溶液中；其中，三羟甲基氨基甲烷-盐酸溶液的浓度为0.1mmol/L-5mmol/L；所述多巴胺溶液中盐酸多巴胺的浓度为0.1g/L-1g/L。
  8. 根据权利要求1所述的纳滤复合膜的制备方法，其特征在于，在所述氧化石墨烯层背离所述第一多孔基材的一侧设置第二多孔基材之前，还包括形成包覆所述第二多孔基材的第二粘结层的步骤；在所述氧化石墨烯层背离所述第一多孔基材的一侧设置所述第二多孔基材之后，所述氧化石墨烯层的一侧表面与所述第二粘结层粘结。
  9. 一种纳滤复合膜，其特征在于，采用权利要求1至8任一项所述的纳滤复合膜的制备方法制得。
  10. 一种如权利要求9所述的纳滤复合膜在处理CO2制烯烃废液中的应用。
PCT/CN2023/076667 2022-03-28 2023-02-17 一种纳滤复合膜及其制备方法 WO2023185303A1 (zh)

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