阅读说明：本技术 一种基于两性离子功能化氧化石墨烯的分离膜及其制备方法 (Separation membrane based on zwitterion functionalized graphene oxide and preparation method thereof ) 是由 金万勤 赵静 梁凤 于 2019-08-28 设计创作，主要内容包括：本发明涉及一种基于两性离子功能化氧化石墨烯的分离膜及其制备方法,将两性离子修饰后的氧化石墨烯与聚合物在支撑体表面交替旋涂,层层自组装得到致密无缺陷的分离膜。该分离膜利用两性离子修饰后的氧化石墨烯的层状结构和对水的亲和力,使得水分子快速传输,同时利用其与聚合物的协同作用构建稳定的膜结构,最终在醇水分离体系中展现出良好的水选择性分离。本发明方法工艺简单经济,实现了高通量、高分离选择性,并保证了膜结构的稳定性,提高了膜的分离效率,同时其具有普适性,有良好的应用前景。(The invention relates to a separation membrane based on zwitterion functionalized graphene oxide and a preparation method thereof. The separation membrane utilizes the layered structure of the graphene oxide modified by zwitterions and the affinity to water, so that water molecules are rapidly transmitted, and meanwhile, a stable membrane structure is constructed by utilizing the synergistic effect of the graphene oxide and a polymer, and finally, good water selective separation is shown in an alcohol-water separation system. The method disclosed by the invention is simple and economic in process, realizes high flux and high separation selectivity, ensures the stability of the membrane structure, improves the separation efficiency of the membrane, and has universality and good application prospect.)

1. A separation membrane based on zwitterion functionalized graphene oxide is characterized in that: the graphene oxide membrane is composed of a separation layer and a support layer, wherein the membrane layer formed by alternately spin-coating a polymer solution and a functionalized graphene oxide solution is used as the separation layer, and the polymer ultrafiltration membrane is used as the support layer.

2. A method for preparing the separation membrane of claim 1, comprising the following steps:

(1) zwitterionic functionalized graphene oxide: respectively dispersing graphene oxide nanosheets, amine compounds and ester compounds in the same organic solvent, adding the amine compound solution into the graphene oxide solution, reacting for 1-2h at 40-60 ℃, then adding the ester compound solution, and reacting for 3-5h at 40-60 ℃; centrifuging to prepare a precipitate, washing by an alcohol solvent, and drying in vacuum to obtain a zwitterion functionalized graphene oxide nanosheet;

(2) Preparing a membrane preparation liquid: uniformly dispersing the prepared zwitterion functionalized graphene oxide nanosheets in a solvent to prepare a graphene oxide membrane preparation solution with the concentration of 0.1-0.4mg/ml for later use; uniformly dispersing the polymer in a solvent to prepare a polymer solution with the concentration of 0.2-0.6mg/ml for later use;

(3) Preparation of the film: placing a support body in a spin coater, alternately spin-coating the polymer solution prepared in the step (2) and the graphene oxide membrane-making solution on the polymer ultrafiltration membrane support body, after a layer of polymer solution is spin-coated, spin-coating and washing with deionized water once, then spin-coating a layer of graphene oxide membrane-making solution, and spin-coating and washing with deionized water once;

(4) and (4) circularly operating the step (3) to the required number of layers, and finally placing the prepared membrane in a vacuum drying oven for drying.

3. The method according to claim 2, wherein the polymeric ultrafiltration membrane support is made of at least one of polyacrylonitrile, polycarbonate or polyvinylidene fluoride.

4. The method according to claim 2, wherein the organic solvent in the step (1) is one of 1-methyl-2-pyrrolidone, N-2-methylformamide, acetone, or dimethylsulfoxide; the alcohol solvent is one of methanol or ethanol.

5. The method according to claim 2, wherein the amine compound in the step (1) is one of ethanolamine or ethylenediamine; the ester compound is one of propane sultone or butane lactone.

6. The preparation method according to claim 2, characterized in that the concentration of the graphene oxide nanosheet solution in step (1) is 0.2-0.5mg/ml, and the concentrations of the amine compound and the ester compound are both 1-5 mg/ml; the mass of the amine compound is 2-6 times that of the graphene oxide; the mass of the ester compound is 1-2 times of that of the compound A.

7. The method according to claim 2, wherein the rotation speed of the centrifugation in step (1) is 8000-12000rpm, and the time of the centrifugation is 10-30 min; the drying temperature is 25-50 ℃.

8. the method according to claim 2, wherein the solvent in step (2) is one of water, an aqueous ethanol solution or an aqueous methanol solution; the polymer is one of polydiallyldimethylammonium, polyethyleneimine or polyallylamine hydrochloride.

9. The production method according to claim 2, characterized in that the spin-coating conditions described in step (3): the rotation speed is 1000-2000rpm, and the time is 30-60 s.

10. the method according to claim 1, wherein the required number of layers in the step (4) is 5 to 20; the drying temperature is 25-50 ℃.

Technical Field

The invention relates to a separation membrane based on zwitterion functionalized graphene oxide and a preparation method thereof, and the prepared membrane can be used for selective rapid permeation of water in an alcohol-water system.

Background

Material separation (purification, recovery and recycling) is a crucial component in various chemical industries, which accounts for a large part of the energy consumption, operation and capital costs in industrial production. Therefore, the development of a novel efficient and energy-saving separation process is a main direction for realizing energy conservation and emission reduction in the chemical industry, and has important significance for sustainable development of the chemical industry. Compared with the traditional separation technologies such as rectification, evaporation, drying and the like, the membrane separation technology is an energy-saving and environment-friendly separation technology and has the characteristics of high separation efficiency and low carbon emission.

Graphene oxide is a representative two-dimensional membrane material, has the thickness of a monoatomic layer, is easy to chemically modify, is easy to assemble to form a regular and adjustable nano mass transfer channel, and shows great prospect in the development of high-performance membrane materials. However, in aqueous environments, the swelling phenomenon of graphene oxide membranes and the restrictive relationship between membrane permeation flux and selectivity remain key challenges for achieving high efficiency separation processes. To address this problem, researchers have developed various regulatory approaches such as partial reduction, covalent crosslinking, and external pressure regulation. However, most of these studies have focused on modulating the physical size of the mass transfer channels between graphene oxide membrane layers, which typically results in increased separation factors and stability, but with a concomitant decrease in flux, also results in lower separation efficiency. Therefore, there is an urgent need to develop an efficient method while achieving high flux, separation selectivity and membrane structure stability.

Disclosure of Invention

The invention aims to provide a separation membrane based on zwitterion functionalized graphene oxide, and the invention also aims to provide a preparation method of the separation membrane. The composite membrane prepared by the method shows good permeation flux, separation selectivity and stability in the separation of an alcohol-water system. The preparation method is simple and easy to implement, and is green and environment-friendly.

The technical scheme of the invention is as follows: a separation membrane based on zwitterion functionalized graphene oxide is characterized in that: the graphene oxide membrane is composed of a separation layer and a support layer, wherein the membrane layer formed by alternately spin-coating a polymer solution and a functionalized graphene oxide solution is used as the separation layer, and the polymer ultrafiltration membrane is used as the support layer.

Preferably, the thickness of the separation layer is 15-55 nm.

The invention also provides a method for preparing the separation membrane, which comprises the following steps:

(1) Zwitterionic functionalized graphene oxide: respectively dispersing graphene oxide nanosheets, amine compounds and ester compounds in the same organic solvent, adding the amine compound solution into the graphene oxide solution, reacting for 1-2h at 40-60 ℃, then adding the ester compound solution, and reacting for 3-5h at 40-60 ℃; centrifuging to prepare a precipitate, washing by an alcohol solvent, and drying in vacuum to obtain a zwitterion functionalized graphene oxide nanosheet;

(2) Preparing a membrane preparation liquid: uniformly dispersing the prepared zwitterion functionalized graphene oxide nanosheets in a solvent to prepare a graphene oxide membrane preparation solution with the concentration of 0.1-0.4mg/ml for later use; uniformly dispersing the polymer in a solvent to prepare a polymer solution with the concentration of 0.2-0.6mg/ml for later use;

(3) Preparation of the film: placing a support body in a spin coater, alternately spin-coating the polymer solution prepared in the step (2) and the graphene oxide membrane-making solution on the polymer ultrafiltration membrane support body, after a layer of polymer solution is spin-coated, spin-coating and washing with deionized water once, then spin-coating a layer of graphene oxide membrane-making solution, and spin-coating and washing with deionized water once;

(4) And (4) circularly operating the step (3) to the required number of layers, and finally placing the prepared membrane in a vacuum drying oven for drying.

Preferably, the material of the polymer ultrafiltration membrane support is at least one of polyacrylonitrile, polycarbonate or polyvinylidene fluoride.

Preferably, the organic solvent is one of 1-methyl-2-pyrrolidone, N-N-2-methylformamide, acetone or dimethyl sulfoxide; the alcohol solvent is one of methanol or ethanol.

Preferably, the amine compound in the step (1) is one of ethanolamine or ethylenediamine; the ester compound is one of propane sultone or butane lactone.

Preferably, the concentration of the graphene oxide nanosheet solution in the step (1) is 0.2-0.5mg/ml, and the concentrations of the amine compound and the ester compound are both 1-5 mg/ml; the mass of the amine compound is 2-6 times that of the graphene oxide; the mass of the ester compound is 1-2 times of that of the compound A.

Preferably, the rotation speed of the centrifugation in the step (1) is 8000-12000rpm, and the centrifugation time is 10-30 min; the drying temperature is 25-50 ℃.

Preferably, the solvent in the step (2) is one of water, ethanol water solution or methanol water solution; the polymer is one of polydiallyldimethylammonium, polyethyleneimine or polyallylamine hydrochloride.

The spin coating conditions described in step (3) are preferred: the rotation speed is 1000-2000rpm, and the time is 30-60 s.

Preferably, the required number of layers in the step (4) is 5-20; the drying temperature is 25-50 ℃.

The separation membrane obtained by the vegetation of the invention has excellent separation performance on ethanol/water systems, when the temperature is 70 ℃, and the water content on the raw material side is 10%, the flux of the membrane is 2277-3995 g/m ² h, and the separation factor is 42-1958.

Has the advantages that:

According to the method disclosed by the invention, zwitterion modification is carried out on graphene oxide, the affinity of graphene oxide to water molecules is enhanced, the construction of a rapid water transmission channel is promoted under the synergistic effect of graphene oxide and polymers, high flux, high separation selectivity and high membrane structure stability are obtained, and the efficiency of a membrane separation process is improved. The thickness and the structure of the membrane are controlled by adjusting the relevant preparation conditions of the membrane, and the separation performance of the membrane is effectively regulated and controlled to adapt to different separation requirements. The method has simple and economic process and wide application range.

Drawings

FIG. 1 is a scanning electron micrograph of a cross section of the film obtained in example 5.

Detailed Description

Comparative example 1

(1) And dispersing the graphene oxide nanosheets in a deionized water solution with the concentration of 0.2mg/ml, and dispersing polyethyleneimine in the deionized water solution with the concentration of 0.2 mg/ml.

(2) And (3) alternately spin-coating 5 layers of the solution in the step (1) on a polyacrylonitrile support body at 2000rpm for 60 s.

(3) The prepared membrane is dried in vacuum at 25 ℃ to obtain a separation membrane, the thickness of the separation layer is 15nm, the separation performance of the membrane prepared in the example on an ethanol/water system is measured, when the temperature is 70 ℃ and the water content on the raw material side is 10%, the flux of the membrane is 6800g/m ² h, and the separation factor is 16.