阅读说明：本技术 一种两亲性氧化石墨烯改性超薄复合纳滤膜及其制备方法与应用 (Amphipathic graphene oxide modified ultrathin composite nanofiltration membrane as well as preparation method and application thereof ) 是由 张国亮 李洋 于 2019-08-29 设计创作，主要内容包括：本发明公开了一种两亲性氧化石墨烯改性超薄复合纳滤膜及其制备方法与应用。所述的制备方法为：将两亲性的氧化石墨烯分散于水溶液中得到两亲性的氧化石墨烯分散液,然后将所述的两亲性的氧化石墨烯分散液和哌嗪的水溶液混合得到水相,然后将油相均苯三甲酰氯的正己烷溶液加入到所述的水相中,界面处发生聚合反应,生成超薄膜；将超滤膜底膜放置在界面处与制得的超薄膜贴合,然后取出覆有超薄膜的超滤膜底膜进行干燥,得到两亲性氧化石墨烯改性超薄复合纳滤膜。本发明将两亲性的氧化石墨烯引入了界面聚合的过程中,利用水油两项的界面性质在界面聚合反应的同时将两亲性氧化石墨烯包裹在内,制备了具有较强亲水性的膜,显著提高了纳滤膜的通量。(The invention discloses an amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane as well as a preparation method and application thereof. The preparation method comprises the following steps: dispersing amphiphilic graphene oxide in an aqueous solution to obtain an amphiphilic graphene oxide dispersion solution, mixing the amphiphilic graphene oxide dispersion solution and an aqueous solution of piperazine to obtain a water phase, adding an n-hexane solution of oil-phase trimesoyl chloride into the water phase, and carrying out polymerization reaction at an interface to generate a ultrathin membrane; and placing the ultrafiltration membrane base membrane at the interface to be attached to the prepared ultrathin membrane, and then taking out the ultrafiltration membrane base membrane coated with the ultrathin membrane for drying to obtain the amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane. According to the invention, amphiphilic graphene oxide is introduced into the interfacial polymerization process, and the amphiphilic graphene oxide is wrapped in the interfacial polymerization reaction by using the interfacial properties of water and oil, so that a membrane with stronger hydrophilicity is prepared, and the flux of the nanofiltration membrane is obviously improved.)

1. an ultra-thin composite nanofiltration membrane of amphipathic nature oxidation graphite alkene modification which characterized in that: the amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane is prepared by the following method:

(1) Dispersing amphiphilic graphene oxide in an aqueous solution to obtain an amphiphilic graphene oxide dispersion solution with the concentration of 0.01-0.8 g/L, mixing the amphiphilic graphene oxide dispersion solution with an aqueous solution of piperazine with the mass fraction of 0.1% -3% to obtain an aqueous phase, adding an n-hexane solution of trimesoyl chloride with the mass fraction of 0.01% -1% of an oil phase into the aqueous phase, and carrying out polymerization reaction at the interface of the oil phase and the aqueous phase to generate an ultrathin membrane; the mass ratio of the amphiphilic graphene oxide to the piperazine is 0.1-20: 1;

(2) And (3) placing an ultrafiltration membrane bottom membrane at the interface close to the oil phase side to be completely attached to the ultrathin membrane prepared in the step (1), taking out the ultrafiltration membrane bottom membrane coated with the ultrathin membrane, and drying in an oven to obtain the amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane.

2. The amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane of claim 1, wherein: in the step (1), the synthesis method of the amphiphilic graphene oxide comprises the following steps: uniformly mixing white cassava starch and deionized water to obtain a starch solution with the concentration of 0.16g/mL, slowly adding 1mg/mL graphene oxide dispersion liquid into the starch solution, stirring for 8 hours at room temperature to obtain an anhydrous ethanol solution of starch microspheres, mixing the starch microspheres with the anhydrous ethanol solution after washing with the deionized water and ethanol, wherein the addition amount of the anhydrous ethanol is 5mL/mg based on the mass of the white cassava starch, then adding an anhydrous ethanol solution of alkylamine with the concentration of 6mg/mL into the anhydrous ethanol solution of the starch microspheres, the volume ratio of the anhydrous ethanol of the alkylamine to the anhydrous ethanol solution of the starch microspheres is 1:4, stirring and reacting for 12 hours at room temperature, washing the obtained microspheres with the anhydrous ethanol, and then dispersing in the anhydrous ethanol again, and carrying out ultrasonic treatment for 10-30 min, then heating for 10-30 min at 50-80 ℃ for 3 times alternately to obtain two phases, and filtering and drying the upper phase to obtain the amphiphilic graphene oxide.

3. The amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane of claim 1, wherein: in the step (2), the drying temperature is 60-90 ℃.

4. The amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane of claim 1, wherein: the preparation method of the ultrafiltration membrane basement membrane comprises the following steps: dissolving a base membrane material in a polar organic solvent to obtain a casting membrane solution with the mass fraction of 8-20%, stirring the obtained casting membrane solution for 12 hours, standing for more than 4 hours, pouring the casting membrane solution on a glass plate, scraping the glass plate by using a scraper, standing in the air for about 15s, then soaking in a water bath to complete phase inversion, and soaking in water for 12 hours to obtain the ultrafiltration membrane base membrane.

5. The amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane of claim 4, wherein: the basement membrane material comprises polyvinylidene fluoride, polypropylene, polyacrylonitrile, polyethylene, polyvinyl chloride, polysulfone, polyether sulfone or polyimide and the like.

6. The amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane of claim 4, wherein: the polar organic solvent is N, N-dimethylformamide, N-methylpyrrolidone or dimethylacetamide.

7. The amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane as claimed in claim 1, applied to seawater desalination.

Technical Field

The invention relates to an amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane as well as a preparation method and application thereof, belonging to the technical field of functional membrane preparation and separation application.

Background

In 1972, Cadotte firstly applies an interfacial polymerization method to prepare a high-performance reverse osmosis composite membrane NS100, the salt rejection rate and the water flux of the membrane are greatly improved compared with those of the membrane prepared by the L-S method, and 90 percent of the current reverse osmosis/nanofiltration membranes worldwide are produced by the interfacial polymerization method.

In recent years, the research heat of interfacial polymerization is still not reduced, the Zhang teacher team of Zhejiang university deeply analyzes the formation process of the interfacial polymerization nanofiltration membrane, and different inhibitors are used for regulating and controlling the membrane surface obtained by interfacial polymerization to construct a Tuling structure. Many groups improve the performance of interfacial polymeric films by means of surface modification, particle doping, and the like. However, the low flux of the interfacial polymerization membrane in practical application now leads to insufficient efficiency of water treatment.

Disclosure of Invention

In order to solve the problems in the prior art, the invention aims to prepare an amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane to realize high-efficiency water treatment, and the amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane is applied to seawater desalination.

The technical scheme of the invention is as follows:

Firstly, graphene oxide sheets with amphiphilic performance are prepared, the graphene oxide sheets are doped into a water phase to carry out interfacial polymerization, then the ultrathin layer is transferred to the surface of a self-made ultrafiltration membrane to prepare a polyamide layer in an interfacial polymerization mode, and the polyamide layer is immersed in water to be stored after heat treatment to obtain the modified interfacial polymerization membrane.

An amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane is prepared by the following steps:

(1) Dispersing amphiphilic graphene oxide into an aqueous solution to obtain an amphiphilic graphene oxide (AJN) dispersion liquid with the concentration of 0.01-0.8 g/L, mixing the amphiphilic graphene oxide (AJN) dispersion liquid with an aqueous solution of piperazine with the mass fraction of 0.1% -3% to obtain an aqueous phase, adding an n-hexane solution of trimesoyl chloride with the mass fraction of 0.01% -1% of an oil phase into the aqueous phase, and carrying out polymerization reaction at the interface of the oil phase and the aqueous phase to generate an ultrathin membrane; the mass ratio of the amphiphilic graphene oxide to the piperazine is 0.1-20: 1;

(2) And (2) placing an ultrafiltration membrane bottom membrane at the interface close to the oil phase side to be completely attached to the ultrathin membrane prepared in the step (1), taking out the ultrafiltration membrane bottom membrane coated with the ultrathin membrane, drying the ultrafiltration membrane bottom membrane in an oven to obtain the amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane, and then placing the composite nanofiltration membrane in water for storage.

Further, in the step (1), the synthesis method of the amphiphilic graphene oxide comprises the steps of uniformly mixing white tapioca starch and deionized water to obtain a starch solution with the concentration of 0.16g/mL, slowly adding 1mg/mL of graphene oxide dispersion liquid into the starch solution, stirring at room temperature for 8 hours to obtain an anhydrous ethanol solution of starch microspheres, washing the starch microspheres with deionized water and ethanol, mixing with the anhydrous ethanol solution to obtain the anhydrous ethanol solution of starch microspheres, wherein the addition amount of the anhydrous ethanol is 5mL/mg based on the mass of the white tapioca starch, then adding an anhydrous ethanol solution of alkylamine with the concentration of 6mg/mL into the anhydrous ethanol solution of starch microspheres, and the volume ratio of the anhydrous ethanol of the alkylamine to the anhydrous ethanol solution of the starch microspheres is 1: 4; and (2) mildly stirring for 12h at room temperature, washing the obtained microspheres with absolute ethyl alcohol, dispersing the microspheres in the absolute ethyl alcohol again, performing ultrasonic treatment for 10-30 min, heating for 10-30 min at 50-80 ℃ for 3 times alternately to obtain two phases, and filtering and drying the upper phase to obtain AJN.

Further, the preparation method of the graphene oxide comprises the following steps of preparing graphite oxide by a modified Hummers method, adding flake graphite and sodium nitrate into 98% concentrated sulfuric acid in an ice bath, continuously stirring and slowly adding potassium permanganate, stirring for 1-6 h in an ice bath, then reacting for 0.5-8 h at a constant temperature of 35 ℃, slowly adding deionized water, reacting for 20-200 min at a constant temperature of 98 ℃, cooling, slowly adding 30% hydrogen peroxide, centrifuging to obtain a product, washing for a plurality of times by using dilute hydrochloric acid, and drying to obtain graphite oxide; the mass ratio of the crystalline flake graphite to the sodium nitrate to the potassium permanganate is 1: 0.25-2.5: 1-5; the adding amount of the deionized water is 40-120 ml/g based on the mass of the crystalline flake graphite.

Further, in the step (2), the drying temperature is 60-90 ℃.

Further, the preparation method of the ultrafiltration membrane basement membrane comprises the following steps: dissolving a base membrane material in a polar organic solvent to obtain a casting membrane solution with the mass fraction of 8-20%, stirring the obtained casting membrane solution for 12h, standing for more than 4h, pouring the casting membrane solution on a glass plate, scraping the glass plate with a scraper of 200 mu m, standing in the air for about 15s, then immersing in a water bath to complete phase inversion, immersing in water for more than 12h to obtain an ultrafiltration membrane base membrane, and cutting into the required size for later use.

Still further, the base membrane material comprises polyvinylidene fluoride, polypropylene, polyacrylonitrile, polyethylene, polyvinyl chloride, polysulfone, polyethersulfone or polyimide, and the like.

Still further, the polar organic solvent may be N, N-dimethylformamide, N-methylpyrrolidone, dimethylacetamide, or the like.

The amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane is applied to seawater desalination.

compared with the prior art, the invention has the advantages that: in the process of introducing amphiphilic graphene oxide into interfacial polymerization, amphiphilic graphene oxide is wrapped in the interfacial polymerization reaction by using the interfacial properties of water and oil, so that a membrane with high hydrophilicity is prepared, and the flux of the nanofiltration membrane is remarkably improved.

The invention is further illustrated by the following examples.

Drawings

Fig. 1 is an SEM image of the surface of an amphiphilic graphene oxide modified ultrathin composite nanofiltration membrane.

Detailed Description

The present invention will be described in detail below with reference to specific examples, but the present invention is not limited to the following examples, and various modifications and implementations are included within the technical scope of the present invention without departing from the content and scope of the present invention.

Materials and reagents required in the preparation of the composite membrane:

Polysulfone (PSF) shanghai eosino photochemical plant, polyvinylidene fluoride (PVDF) shanghai eosino photochemical plant, Polyethersulfone (PES) shanghai eosino photochemical plant, polypropylene (PP) shanghai eosino photochemical plant, Polyacrylonitrile (PAN) shanghai eosino photochemical plant, polyvinyl chloride (PVC) shanghai eosino photochemical plant, anhydrous methanol alatin reagent (shanghai) limited, high-purity crystalline flake graphite, potassium permanganate, 30% hydrogen peroxide (H2O2) alatin reagent (shanghai) limited, potassium permanganate (KMnO4), sodium sulfate (Na2SO4), magnesium sulfate (MgSO4), magnesium chloride (MgCl2), sodium nitrate (NaNO3), sodium chloride (NaCl), N-Dimethylformamide (DMF), N-methylpyrrolidone (NMP), Dimethylacetamide (DMAC) national medicine group chemical reagent limited.

Example 1

Preparing a polysulfone ultrafiltration membrane: preparing 12% of casting solution by mass, wherein the raw material and the polar solvent are polysulfone and NMP respectively. Scraping into ultrafiltration membrane by phase inversion method, and cutting into desired size.

Preparation of amphiphilic graphene oxide (AJN): 40g of white tapioca starch was mixed with 250mL of deionized water and stirred continuously. 100mg of GO is uniformly dispersed in 100mL of DI water, sonicated for a period of time, then the GO dispersion is slowly added to the starch mixture in water and stirred at room temperature for 8 hours, after washing with DI water and ethanol, the starch microspheres are mixed with 200mL of absolute ethanol solution, then 300mg of alkylamine dissolved in 50mL of absolute ethanol is added and stirring is carried out at room temperature for 12 hours. After washing with absolute ethyl alcohol, dispersing the starch microspheres in the absolute ethyl alcohol again, and alternately performing ultrasonic treatment and heating for 15min, and then heating for 15min at 55 ℃ for 3 times. The fluid system is divided into two phases, with AJN dispersed in the upper phase. Filtration and drying gave about 70mg of AJN.

preparation of the film: preparing 20mL of piperazine water solution with the mass fraction of 2%, and adding 3mL of AJN water solution with the mass fraction of 0.1g/L, wherein the solution is called A; preparing 0.1 mass percent of trimesoyl chloride normal hexane solution called B; and pouring the solution B above the solution A, and carrying out polymerization reaction at an interface to generate the ultrathin film. Then transferring the hydrophilic surface of the mixture to a self-made ultrafiltration bottom membrane, drying the mixture in an oven for 10min, and transferring the mixture to an aqueous phase for storage.

And (3) performance testing: the performance of the membrane is tested on a cross flow device, and the water flux of the membrane is 15.6L/(m) under 0.6MPa and 25L/h²H.bar) with a sodium sulfate rejection of 95.8%.

Example 2

Preparing a polysulfone ultrafiltration membrane: preparing 12% of casting solution by mass, wherein the raw material and the polar solvent are polysulfone and NMP respectively. Scraping into ultrafiltration membrane by phase inversion method, and cutting into desired size.

preparation of amphiphilic graphene oxide (AJN): 40g of white tapioca starch was mixed with 250mL of deionized water and stirred continuously. 100mg of GO was uniformly dispersed in 100mL DI water, sonicated for a period of time, and then the GO dispersion was slowly added to the starch mixture in water and stirred at room temperature for 8 hours. After washing with DI water and ethanol, the starch microspheres were mixed with 200mL of absolute ethanol solution, and then 300mg of alkylamine dissolved in 50mL of absolute ethanol was added. The reaction was allowed to proceed at room temperature with gentle stirring for 12 h. After washing with ethanol, dispersing the starch microspheres in absolute ethanol again, and alternately performing ultrasonic treatment and heating for 15min, and then heating for 15min at 55 ℃ for 3 times. The fluid system is divided into two phases, with AJN dispersed in the upper phase. Filtration and drying gave about 70mg of AJN.

Preparation of the film: preparing 20mL of piperazine water solution with the mass fraction of 2%, and adding 6mL of AJN water solution with the mass fraction of 0.1g/L, wherein the solution is called A; preparing 0.1 mass percent of trimesoyl chloride normal hexane solution called B; and pouring the solution B above the solution A, and carrying out polymerization reaction at an interface to generate the ultrathin film. Then transferring the hydrophilic surface of the mixture to a self-made ultrafiltration bottom membrane, drying the mixture in an oven for 10min, and transferring the mixture to an aqueous phase for storage.

And (3) performance testing: the performance of the membrane is tested on a cross flow device, and the water flux of the membrane is 14.2L/(m) under 0.6MPa and 25L/h²H.bar), sulfuric acidthe sodium rejection was 96.0%.

Comparative example 1

Preparing a polysulfone ultrafiltration membrane: preparing 12% of casting solution by mass, wherein the raw material and the polar solvent are polysulfone and NMP respectively. Scraping into ultrafiltration membrane by phase inversion method, and cutting into desired size.

Preparation of amphiphilic graphene oxide (AJN): 40g of white tapioca starch was mixed with 250mL of deionized water and stirred continuously. 100mg of GO was uniformly dispersed in 100mL DI water, sonicated for a period of time, and then the GO dispersion was slowly added to the starch mixture in water and stirred at room temperature for 8 hours. After washing with DI water and ethanol, the starch microspheres were mixed with 200mL of absolute ethanol solution, and then 300mg of alkylamine dissolved in 50mL of absolute ethanol was added. The reaction was allowed to proceed at room temperature with gentle stirring for 12 h. After washing with ethanol, dispersing the starch microspheres in absolute ethanol again, and alternately performing ultrasonic treatment and heating for 15min, and then heating for 15min at 55 ℃ for 3 times. The fluid system is divided into two phases, with AJN dispersed in the upper phase. Filtration and drying gave about 70mg of AJN.

Preparation of the film: preparing 20mL of piperazine water solution with the mass fraction of 2%, wherein the solution is called A; preparing 0.1 mass percent of trimesoyl chloride normal hexane solution called B; and pouring the solution B above the solution A, and carrying out polymerization reaction at an interface to generate the ultrathin film. Then transferring the hydrophilic surface of the mixture to a self-made ultrafiltration bottom membrane, drying the mixture in an oven for 10min, and transferring the mixture to an aqueous phase for storage.

And (3) performance testing: the performance of the membrane is tested on a cross flow device, and the water flux of the membrane is 10.2L/(m) under 0.6MPa and 25L/h²H.bar) with a sodium sulfate rejection of 95.3%.