Polyamide composite membrane and preparation method thereof

Abstract

The invention provides a polyamide composite membrane and a preparation method thereof. The polyamide composite membrane comprises a supporting layer, a modified layer and a polyamide layer; the modified layer grows on the supporting layer; the polyamide layer grows on the modified layer; the polyamide layer is prepared from the following raw material components: polyamine, polyacyl chloride and hollow polydopamine microspheres; the diameter of the hollow polydopamine microspheres is 50 to 200 nm; and the modified layer is used for regulating and controlling the thickness and the crosslinking degree of the polyamide layer. The preparation method comprises the steps: step 1, preparing the supporting layer; step 2, growing the modified layer on the supporting layer to obtain a composite layer; and step 3, growing the polyamide layer on the modified layer of the composite layer to obtain the polyamide composite film. The polyamide composite membrane prepared by the method can effectively improve the water flux and improve the permeation efficiency of the polyamide composite film under the condition of keeping a high rejection rate.

Description

technical field [0001] The invention relates to the technical field of reverse osmosis membranes, in particular to a polyamide composite membrane and a preparation method thereof. Background technique [0002] Polyamide composite membrane has the advantages of high rejection rate, large water flux, good chemical stability, wide pH range (pH value 4-11) and low operating pressure requirements, and is widely used in drinking water purification, ultrapure water Preparation, brackish water desalination, seawater desalination and reclaimed water reuse. Water flux is one of the most important performance parameters of polyamide composite membranes. The higher the water flux, the lower the energy consumption of equipment using polyamide composite membranes when processing the same amount of liquid. Therefore, increasing the water flux is very important to reduce the energy consumption of equipment operation. [0003] At present, some technicians have proposed to add nanoparticles...

AI Technical Summary

Problems solved by technology

[0004] Although the above-mentioned nanoparticles can improve the permeation flux of the polyamide composite membrane, there is no chemical bond between the polymer and the nanoparticles in the polyamide composite membrane, and only rely on the intermolecular affinity, so that the nanoparticles cannot pass through the polyamide composite membrane. Stable existence, greatly reducing the service life of the polyamide composite membrane

In addition, when the nanoparticles are polymerized at the interface of the polyamide composite membrane, they are easy to agglomerate in the polymer matrix, resulting in the formation of non-selective voids in the prepared polyamide composite membrane, which leads to a decrease in the selectivity of the polyamide composite membrane, resulting in polyamide composite The problem of low membrane salt interception performance

[0005] In summary, there is an urgent need for a polyamide composite membrane and its preparation method to solve the problem that the nanoparticles in the prior art cannot exist stably in the polyamide composite membrane, and when the nanoparticles are polymerized at the interface of the polyamide composite membrane, they are easily separated. Problems with agglomeration in polymer matrices

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