Polyamide hollow fiber nanofiltration composite membrane and preparation method thereof

Abstract

The invention provides a polyamide hollow fiber nanofiltration composite membrane and a preparation method thereof. The preparation method comprises the following steps: 1, activating a polyamide hollow fiber ultrafiltration membrane to form carboxylic acid groups and amino groups on the surface of the polyamide hollow fiber ultrafiltration membrane; 2, putting the activated polyamide hollow fiberultrafiltration membrane into a polyamine aqueous solution; 3, taking out the polyamide hollow fiber ultrafiltration membrane from the polyamine aqueous solution, and putting the polyamide hollow fiber ultrafiltration membrane into a polyacyl chloride organic solution, wherein an interfacial polymerization reaction is generated on the surface of the polyamide hollow fiber ultrafiltration membraneto form a separation layer; and 4, taking out the polyamide hollow fiber ultrafiltration membrane with the separation layer from the polyacyl chloride organic solution, and carrying out heat treatment on the polyamide hollow fiber ultrafiltration membrane to obtain the polyamide hollow fiber nanofiltration composite membrane. By utilizing the method, the structural defects of the membrane separation layer can be effectively reduced, the connection tightness between the base membrane and the separation layer is enhanced, and the use performance of the membrane is improved.

Description

technical field [0001] The invention relates to the technical field of preparation of separation membranes, in particular to a polyamide hollow fiber nanofiltration composite membrane and a preparation method thereof. Background technique [0002] Nanofiltration membrane is a kind of membrane material with special separation function. Its membrane pore size is between 1-10 nanometers. Divalent or multivalent ions and organic matter with a molecular weight between 200 and 1000 have a good removal rate. In view of the special separation scale of nanofiltration membrane, nanofiltration membrane can be used for water softening (calcium and magnesium ion interception) and detoxification (microorganism, heavy metal interception), purification and concentration of special chemical raw materials (such as dyes, drugs, biomass) and The field of oil-water separation. At the same time, because the nanofiltration membrane still has a high flux under a low pressure (0.2-1 MPa), it effec...

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Problems solved by technology

However, this type of composite roll element has structural limitations: 1) In addition to the diaphragm, the roll element is equipped with modules such as water collection pipes, spacers, and inter-membrane support nets, which occupy a large amount of space in the membrane and limit the capacity of the membrane. The filling density restricts the water production efficiency; 2) The pollutants in the narrow flow channel are not easy to be washed out, and fouling is easy to occur after long-term operation. treatment process, which increases the operating cost of the nanofiltration membrane process

[0005] At present, there are two main technical difficulties in the hollow fiber composite nanofiltration membrane: 1) the uneven distribution of reactive monomers on the curved base membrane, and the separation layer formed by polymerization is prone to defects, which affect the separation performance of the membrane; 2) the separation between the base membrane and the separation layer The compatibility of the materials is poor, and the two lack effective physical or chemical interactions at the interface, making the separation layer easy to separate from the base membrane under long-term operation or extreme water quality conditions. This phenomenon occurs in hollow fiber membranes with higher specific surface areas In actual operation (especially in the high-speed cleaning process), the membrane filaments are easy to shake and cause surface friction, which also increases the possibility of the separation layer falling off, which seriously affects the practicability of the membrane.

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