阅读说明：本技术 一种具有水和离子选择性传输性能的离子液体修饰氧化石墨烯膜及其制备方法 (Ionic liquid modified graphene oxide membrane with water and ion selective transmission performance and preparation method thereof ) 是由 张梦辰 赵鹏祥 于 2020-06-04 设计创作，主要内容包括：本发明公开了一种具有水和离子选择性传输性能的离子液体修饰氧化石墨烯膜的制备方法,本发明利用离子液体以非共价方式修饰氧化石墨烯纳米片,精密调控氧化石墨烯膜二维纳米通道的物理结构和化学环境,在压力驱动下有序组装形成离子液体修饰氧化石墨烯膜,该膜的结构稳定,能促进水分子和单价离子快速传输,并能有效截留多价离子,在单价和多价盐溶液体系中展现出高渗透性和高选择性,可用于水净化和离子分离等相关领域。(The invention discloses a preparation method of an ionic liquid modified graphene oxide membrane with water and ion selective transmission performance, which is characterized in that an ionic liquid is utilized to modify a graphene oxide nanosheet in a non-covalent manner, the physical structure and the chemical environment of a two-dimensional nanochannel of the graphene oxide membrane are precisely regulated and controlled, the graphene oxide membrane is orderly assembled under the drive of pressure to form the ionic liquid modified graphene oxide membrane, the membrane has a stable structure, can promote the rapid transmission of water molecules and monovalent ions, can effectively intercept multivalent ions, shows high permeability and high selectivity in a monovalent and multivalent salt solution system, and can be used for the related fields of water purification, ion separation and the like.)

1. A preparation method of an ionic liquid modified graphene oxide membrane with water and ion selective transmission performance is characterized by comprising the following steps:

(1) preparing a graphene oxide dispersion liquid: uniformly dispersing graphene oxide in a solvent to obtain a graphene oxide dispersion liquid;

(2) modifying graphene oxide by using ionic liquid: dissolving the ionic liquid into the graphene oxide dispersion liquid, and uniformly dispersing to obtain an ionic liquid modified graphene oxide membrane-making liquid;

(3) preparing an ionic liquid modified graphene oxide membrane: and assembling the ionic liquid modified graphene oxide membrane-forming solution on a porous support body through pressure driving to form a membrane layer, and drying the membrane layer to obtain the ionic liquid modified graphene oxide membrane.

2. The method for preparing the ionic liquid modified graphene oxide membrane according to claim 1, wherein in the step (1), the solvent is water, an aqueous ethanol solution or an aqueous methanol solution.

3. The method for preparing the ionic liquid modified graphene oxide film according to claim 1, wherein in the step (1), the concentration of the graphene oxide dispersion liquid is 0.005-0.1 mg/mL.

4. The method for preparing the ionic liquid modified graphene oxide membrane according to claim 1, wherein in the step (2), the ionic liquid is a sulfonic acid imidazole ionic liquid and/or a sulfonic acid pyridine ionic liquid.

5. The method for preparing the ionic liquid modified graphene oxide membrane according to claim 1, wherein in the step (2), the addition amount of the ionic liquid is 1-20 mg/mL.

6. The method for preparing the ionic liquid modified graphene oxide membrane according to claim 1, wherein in the step (3), the porous support is made of polyacrylonitrile, polycarbonate, nylon, mixed cellulose ester, zirconium oxide, aluminum oxide, zinc oxide, silicon oxide, or titanium oxide.

7. The method for preparing the ionic liquid modified graphene oxide membrane according to claim 1, wherein in the step (3), the porous support is of a single-tube type, a multi-channel tube type, a hollow fiber type, a sheet type or a flat plate type.

8. The method for preparing the ionic liquid modified graphene oxide membrane according to claim 1, wherein in the step (3), the average pore diameter of the porous support is 10-1000 nm.

9. The method for preparing the ionic liquid modified graphene oxide membrane according to claim 1, wherein in the step (3), the pressure driving method is filtration or vacuum suction, wherein the filtration pressure is 0.1-0.6 MPa.

10. The ionic liquid modified graphene oxide membrane is characterized by being prepared by the preparation method of the ionic liquid modified graphene oxide membrane according to any one of claims 1 to 9.

Technical Field

The invention belongs to the technical field of new materials, and particularly relates to an ionic liquid modified graphene oxide membrane with water and ion selective transmission performance and a preparation method thereof.

Background

The selective transmission of water and ions plays a key role in the processes of chemical separation, clean production, energy utilization and the like. Inspiration is acquired from biological nanochannels of natural cell membranes, and the construction of the bionic nanochannels with water and ion selective transmission performance based on novel membrane materials has important significance.

The two-dimensional material represented by graphene oxide has unique atomic-scale thickness, micron-scale side size and adjustable physicochemical properties, can be stacked to form a regular interlayer two-dimensional nano-channel through ordered assembly, is used for molecular and ion transmission, and has wide application prospects in various fields such as environment, resources, energy and the like. However, graphene oxide membranes still face a number of challenges in the selective transport of water and ions. The two-dimensional nanochannel of the graphene oxide membrane is easy to swell in a water environment and lose ion sieving performance. Although the graphene oxide membrane channel can be prevented from swelling by using methods such as physical limitation, chemical reduction or covalent crosslinking, the excessively narrow size of the channel between graphene oxide layers can also bring about large permeation resistance, so that transmembrane transmission of water and ions is hindered, and the membrane separation efficiency is reduced.

Therefore, an effective method needs to be developed, which precisely controls the physical structure and chemical environment of the graphene oxide film two-dimensional nanochannel, and promotes the rapid transmission of water molecules and monovalent ions while trapping multivalent ions, so as to realize the efficient selective transmission of water and ions.

Disclosure of Invention

In order to solve the defects and shortcomings in the prior art, the invention aims to provide an ionic liquid modified graphene oxide membrane with water and ion selective transmission performance and a preparation method thereof. The graphene oxide nanosheets are modified by ionic liquid in a non-covalent manner, and the graphene oxide nanosheets are orderly assembled under the driving of pressure to form the graphene oxide membrane modified by the ionic liquid, the membrane is stable in structure, shows high permeability and high selectivity in a monovalent salt solution system and a multivalent salt solution system, and can be used in the related fields of water purification, ion separation and the like.

In order to realize the purpose, the technical scheme adopted by the invention is as follows:

a preparation method of an ionic liquid modified graphene oxide membrane with water and ion selective transmission performance comprises the following steps:

(1) preparing a graphene oxide dispersion liquid: uniformly dispersing graphene oxide in a solvent to obtain a graphene oxide dispersion liquid;

(2) modifying graphene oxide by using ionic liquid: dissolving the ionic liquid into the graphene oxide dispersion liquid, and uniformly dispersing to obtain an ionic liquid modified graphene oxide membrane-making liquid;

(3) preparing an ionic liquid modified graphene oxide membrane: and assembling the ionic liquid modified graphene oxide membrane-forming solution on a porous support body through pressure driving to form a membrane layer, and drying the membrane layer to obtain the ionic liquid modified graphene oxide membrane.

Preferably, in the step (1), the graphene oxide is monodisperse graphene oxide nanosheets. The monodisperse graphene oxide nanosheet has a very high surface-to-volume ratio, and can be orderly stacked under the assistance of a solvent to form a regular two-dimensional layered membrane structure.

Preferably, in step (1), the solvent is water, an aqueous ethanol solution or an aqueous methanol solution. The graphene oxide nanosheet is good in dispersibility in an aqueous solvent, is not easy to cause a local agglomeration phenomenon, and is beneficial to assembly and preparation of a graphene oxide film.

Preferably, in the step (1), the concentration of the graphene oxide dispersion liquid is 0.005-0.1 mg/mL. Too low concentration of the graphene oxide dispersion liquid can result in lower film preparation efficiency, and too high concentration can affect the dispersibility of the graphene oxide nanosheets in the solvent. When the concentration provided by the invention is used, the membrane preparation efficiency is high, and the dispersibility of the graphene oxide nanosheet in the solvent is good.

Preferably, in the step (1), the graphene oxide material is uniformly dispersed in the solvent by stirring and ultrasonic treatment. Preferably, the stirring time is 10-60 min, the ultrasonic power is 100-700W, and the ultrasonic time is 5-30 min. Proper stirring and ultrasonic processes are favorable for helping graphene oxide nanosheets to be uniformly dispersed in a solvent, and excessive ultrasonic power and ultrasonic time can cause the size of the nanosheets to be too small, so that the structure and performance of the graphene oxide film are affected.

Preferably, in step (2), the ionic liquid is a sulfonic acid imidazole ionic liquid and/or a sulfonic acid pyridine ionic liquid, such as: 1-sulfonic acid butyl-3-methylimidazole inner salt, N-sulfonic acid butyl pyridine p-toluene sulfonate, sulfonic acid propyl pyridine lactone and the like. Preferably, the addition amount of the ionic liquid is 1-20 mg/mL. The imidazole/pyridine group in the ionic liquid can form intermolecular force such as cation-pi effect with the graphene oxide base surface, and the like, and can control the ordered structure and the appropriate interlayer channel size of the graphene oxide membrane two-dimensional layered structure in a water environment. Sulfonic acid groups in the ionic liquid can form rich hydrogen bond action with water molecules, and the water molecules are promoted to enter and be rapidly transferred in channels among graphene oxide membrane layers.

Preferably, in the step (2), the ionic liquid is uniformly dispersed in the graphene oxide dispersion liquid by stirring and ultrasonic treatment. Preferably, the stirring time is 30-120 min, the ultrasonic treatment power is 100-700W, and the ultrasonic time is 5-30 min. Proper stirring and ultrasonic processes are beneficial to fully dissolving the ionic liquid, and the graphene oxide nanosheets and the ionic liquid are ensured to be fully contacted in the solvent, so that the ionic liquid is uniformly attached to the graphene oxide nanosheets through non-covalent action.

Preferably, in step (3), the material of the porous support is polyacrylonitrile, polycarbonate, nylon, mixed cellulose ester, zirconia, alumina, zinc oxide, silicon oxide or titanium oxide. The porous support can provide sufficient mechanical strength to the graphene oxide membrane.

Preferably, the structure type of the porous support is a single-tube type, a multi-channel tube type, a hollow fiber type, a sheet type or a flat plate type.

Preferably, the average pore diameter of the porous support is 10 to 1000 nm. The too small pore diameter of the porous support body can bring extra mass transfer resistance and influence the membrane separation efficiency. The pore diameter of the porous support is too large, so that the nano sheet falls into the pore channel of the support and cannot form a film. The porous support with the pore diameter provided by the invention has better use effect.

Preferably, in the step (3), the pressure-driven method is filtration or vacuum suction, wherein the pressure of the filtration is 0.1-0.6 MPa. Too low a filtration pressure results in lower membrane preparation efficiency and too high a pressure results in compression of the membrane channel structure. When the pressure provided by the invention is used, the membrane preparation effect is higher, and the membrane channel structure is not compressed.

Preferably, in the step (3), the drying temperature is 25-60 ℃, and the drying time is 12-36 h. Residual moisture in the membrane can be removed in the drying process, the membrane preparation efficiency can be reduced due to too low drying temperature, and the partial reduction or removal of oxygen groups in the graphene oxide membrane can be caused due to too high drying temperature, so that the membrane structure is damaged. The drying under the conditions provided by the invention has better effect.

Has the advantages that: the graphene oxide nanosheets are modified by ionic liquid in a non-covalent manner, cationic groups and anionic groups are uniformly introduced between the graphene oxide layers, and the physical structure and the chemical environment of the two-dimensional nanochannel of the graphene oxide film are precisely regulated and controlled. Cationic groups (imidazolyl and pyridyl) of the ionic liquid control the two-dimensional nanochannel structure of the graphene oxide film to be kept in a proper size through pi-pi action, cation-pi action and electrostatic interaction; the anionic group (sulfonic group) of the ionic liquid enhances the affinity of the graphene oxide membrane two-dimensional nano-channel for water molecules and hydrated ions based on hydrogen bonding. Under the synergistic effect of the two, the prepared ionic liquid modified graphene oxide film can promote the rapid transmission of water molecules and monovalent ions, obtain the selective transmission performance of water and ions, can effectively intercept multivalent ions, and has high permeability and high selectivity in monovalent and multivalent salt solution systems. The preparation method is simple and feasible, and the prepared ionic liquid modified graphene oxide membrane has a stable structure and has good application prospects in related fields of water purification, ion separation and the like.

Drawings

Fig. 1 is a cross-sectional scanning electron microscope photograph of the ionic liquid modified graphene oxide film prepared in example 1;

fig. 2 is a surface N element energy spectrum profile of the ionic liquid modified graphene oxide film prepared in example 2;

fig. 3 is a surface S element energy spectrum profile of the ionic liquid modified graphene oxide film prepared in example 2.

Detailed Description

To better illustrate the objects, aspects and advantages of the present invention, the present invention is further illustrated by the following examples. It is apparent that the following examples are only a part of the embodiments of the present invention, and not all of them. It should be understood that the embodiments of the present invention are only for illustrating the technical effects of the present invention, and are not intended to limit the scope of the present invention. Unless otherwise specified, the raw materials used in the examples are all commercially available.