CN-122006528-A - Separation membrane with liquid-like surface and preparation method and application thereof

Abstract

The invention belongs to the technical field of liquid-like surface modified separation membranes, and particularly relates to a separation membrane with a liquid-like surface, a preparation method and application thereof. The invention selects a omentum as a matrix material, adds excessive fluorine-containing alkyl silane into a reaction kettle to carry out high-temperature standing reaction, and washes off the fluorine-containing alkyl silane with weak surface grafting by ethanol to obtain the separation membrane with liquid-like surface. The separation membrane has low surface energy, dynamic characteristics of similar liquid, excellent dirt resistance and chemical stability of fluorine materials, good bonding capability and mechanical strength of silane materials, and can be used for separating immiscible liquid by grafting again after the damage function of a coating is reduced. The separation membrane has extremely low surface energy and extremely low adhesion to oil, can realize high-efficiency and continuous separation of various oil-water mixtures, and has high flux and separation efficiency and long service life.

Inventors

• PENG BO
• ZHAO YIMING
• WANG HAIZHU
• XUE PENG

Assignees

• 复旦大学

Dates

Publication Date

20260512

Application Date

20260309

Claims (6)

1. 1. The preparation method of the separation membrane with the liquid-like surface modification is characterized by comprising the following specific steps: Step 1, selecting a omentum as a matrix material, wherein the thickness is 0.03-0.05 mm, the size is 1-100 cm < 2 >, treating the surface of the matrix for 10-15 min by adopting ethanol, and cleaning the matrix material; Step 2, placing the dried matrix in a reaction kettle, adding excessive fluorine-containing alkyl silane into the reaction kettle, placing the mixture in an oven, and standing the mixture at 90-200 o ℃ for reaction overnight; and step 3, cooling the reacted matrix, and washing off the surface-grafting weak fluorine-containing alkyl silane by using ethanol to obtain a matrix with low surface energy and capable of being used for separating immiscible liquid, namely a separation membrane with a liquid-like surface.
2. 2. The method of preparing a separation membrane with liquid-like surface modification according to claim 1, wherein the fluorine-containing alkylsilane is a short chain fluorine-containing silane having the general formula R-Si (OR ') 3 , wherein R is a fluorine-containing alkyl group of C 4 –C 8 and OR' is a hydrolyzable group.
3. 3. The method for preparing a separation membrane with liquid-like surface modification according to claim 1, wherein the material of the mesh membrane is stainless steel, copper or nickel, or nylon, cotton cloth or filter paper.
4. 4. A liquid-like surface separation membrane obtained by the production process according to any one of claims 1 to 3.
5. 5. The use of a liquid-like surface separation membrane according to claim 4 for separating immiscible liquids by bringing the separation membrane directly into contact with the immiscible liquid to be separated and separating the immiscible liquid by gravity or buoyancy.
6. 6. The application of claim 5, wherein said liquid-like separation membrane is fixed or laid in a separation device in a horizontal or inclined state, and the immiscible liquid mixture to be separated is added above the separation membrane under normal temperature and pressure conditions, and the separation and the delamination of the immiscible liquid are realized by only gravity.

Description

Separation membrane with liquid-like surface and preparation method and application thereof Technical Field The invention belongs to the technical field of liquid-like surface modified separation membranes, and particularly relates to a separation membrane with a liquid-like surface, a preparation method and application thereof. Background In the industrial processes of petrochemical industry, fine chemical industry, solvent extraction and the like, efficient separation of oil-water and oil-oil immiscible liquid systems is a key unit operation. Separation membrane materials based on interface wettability modulation are receiving great attention for being able to achieve selective wetting and low interface adhesion. The prior art generally prepares super-hydrophobic/hydrophilic/oil interfaces by constructing micro-nano coarse structures and combining low surface energy materials, or introduces lubricating liquid into a porous substrate to form a sliding interface. However, the coarse structure is prone to failure under mechanical abrasion or liquid washout, the sliding interface is at risk of loss of lubricating phase, and part of the low surface energy polymer is prone to swelling or aging in an organic solvent, so that the interface stability is insufficient. The liquid-like interface has solid support and liquid dynamic characteristics by constructing a molecular layer with chain segment movement capability on the surface of the solid matrix, so that the liquid contact hysteresis and adhesion can be remarkably reduced, and the problem of free lubrication liquid loss can be avoided. If the molecular layer is stably grafted in a covalent way, the chemical and mechanical stability of the interface can be further improved. Although liquid-like interfaces have found application in the field of anti-adhesion, their use in liquid separation systems, particularly oil-oil separation systems, is still relatively limited. The oil-oil separation material is still relatively deficient for different organic phases compared to the more sophisticated oil-water separation technology. Because of the small difference in surface tension between different oil phases, the traditional separation strategy relying on super-hydrophobic or super-oleophobic structures is difficult to realize precise and selective separation. The prior art such as selective swelling polymer membrane, functional porous membrane and molecular sieve material generally has the problems of insufficient structural stability, complex preparation or difficult large-scale application in the organic solvent environment. In terms of low surface energy interface construction, perfluoro and polyfluoroalkyl materials (PFAS) have extremely low surface energy and excellent chemical resistance due to their stable C-F bonds, and are widely used to prepare superhydrophobic, superoleophobic and liquid-like interfaces. In particular, long chain fluorine-containing modifiers generally impart better durability and stability to the interface. However, long-chain PFAS (greater than 8-CF 2 segments) have a high degree of environmental persistence and bioaccumulation, and have been under increasingly stringent international regulations. In recent years, multiple countries in europe have proposed the implementation of systematic limits on a wide range of PFAS substances. Although short chain fluorochemicals are relatively relaxed in regulatory terms, their modified interfaces are generally less durable than long chain structures. Therefore, achieving a balance of interfacial stability and environmental friendliness while meeting the oil-water and oil-oil separation performance requirements remains a problem that needs to be addressed in the prior art. In order to solve the problems, the invention provides a preparation method of a liquid separation membrane and defines the application of the liquid separation membrane in oil-water and oil-oil immiscible solution separation. According to the technical scheme, short-chain fluorine-containing silane molecules are introduced into the surface of a stainless steel net film substrate and are stably grafted in a covalent bond mode, so that a functional interface with liquid-like dynamic characteristics is constructed, and good chemical stability and mechanical stability are realized while low surface energy is maintained. The interface can be recovered through re-silanization treatment after the separation performance is reduced, has renewable characteristics, and has practical significance in oil-water and oil-oil separation application. Disclosure of Invention The invention aims to overcome the defects of the existing liquid-like surface technology and provides a novel liquid-like separation membrane, and a preparation method and application thereof. The preparation method of the liquid-like separation membrane provided by the invention comprises the following specific steps: step 1, selecting a mesh film with a proper size as a matr