Preparation Method of Polyvinyl Alcohol/Graphite Phase Carbon Nitride Pervaporation Hybrid Membrane

Abstract

The invention discloses a preparation method of a polyvinyl alcohol / graphite-phase carbon nitride pervaporation hybrid membrane. The preparation method includes the steps that graphite-phase carbon nitride (g-C3N4) is adopted as two-dimensional nanometer framework filler, and functional groups (M-g-C3N4) are provided for g-C3N4 through ammonium hydroxide hydrothermal modification; M-g-C3N4 is uniformly dispersed in a polyvinyl alcohol (PVA) solution to form a membrane casting solution through ultrasonic blending, and standing is carried out for defoaming; the defoamed membrane casting solution is spread on a smooth and clean ultrafiltration bottom membrane; the organic / inorganic hybrid membrane is formed through the drying, heating and crosslinking aftertreatment processes. According to the method, a PVA dense separation layer is filled with M-g-C3N4, so that the mechanical strength, heat stability and chemical stability of the membrane are improved, the Trade-off effect of selectivity and permeability of the PVA pervaporation membrane is avoided, and efficient large-scale application of the PVA pervaporation membrane in the organic solvent dehydration field is promoted. In a 90wt.% ethyl alcohol-water evaluation system, the total flux of the membrane with the mass content of M-g-C3N4 being 5% reaches 2000 g / (m<2> h), and the number of separation factors reaches 300 or so.

Description

technical field [0001] The invention belongs to the technical field of membrane materials and separation, and in particular relates to a composite membrane that can be used for pervaporation separation and a preparation method thereof, and is mainly used in the technical field of pervaporation organic matter dehydration. Background technique [0002] The dehydration of organic matter by pervaporation is the most important application field of pervaporation technology. Pervaporation dehydration membrane materials generally use strong hydrophilic polymer materials with rigid chains and can form ion-dipole interactions or hydrogen bonds with water. Among them, polyvinyl alcohol (PVA) with a large number of side hydroxyl groups in the molecular chain is hydrophilic. A typical representative of water-based polymer pervaporation membrane materials, because of its high hydrophilicity, good heat and chemical resistance, resistance to organic pollution and good film-forming propertie...

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Problems solved by technology

The problem of filling these nano-inorganic materials into the organic network matrix is: the agglomeration of inorganic nanoparticles will make the structure of the membrane uneven and reduce the separation performance of the membrane; poor compatibility with polymers will form at the junction of the two components. Non-selective interfaces and pores reduce membrane selectivity

However, except for SA, for other hydrophilic polymer materials, such as PVA, CS, etc., there are few reports on the use of g-C3N4 as an inorganic filler; secondly, chemical modification of g-C3N4 makes it compatible with polymer There is no literature report on the research on the regulation of the microstructure of the organic / inorganic interface in the pervaporation separation layer through the formation of chemical bonds and the strong interaction of coordination bonds.

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