A kind of preparation method of positive charge/negative charge janus nanofiltration membrane

Abstract

The invention discloses a preparation method of a positive / negative Janus nanofiltration membrane, which belongs to the field of preparation of nanofiltration membranes. The present invention is realized according to the following steps: 1. Use sodium polyacrylate / polyvinyl alcohol solution to form a film by uniform hanging coating on one side of the porous base film; 2. Use a crosslinking agent to carry out crosslinking; 3. Use dopamine and polyethyleneimine solution Coat the other side of the membrane, take it out, and clean it with distilled water; 4. Soak it in isopropanol. The membrane prepared by the invention can realize high-efficiency separation of high-valent / monovalent ions with the same chargeability, can be effectively used to remove metal ions and hardness in water, and provides a new idea for solving the problem of drinking water safety.

Description

technical field [0001] The invention relates to a method for preparing a membrane. Background technique [0002] As our country pays more and more attention to the safety of drinking water, our citizens have stricter and stricter requirements on drinking water. However, my country's fresh water resources are scarce, and the content of calcium and magnesium ions and heavy metal ions in water in most areas is high. Traditional treatment methods are difficult to unilaterally remove hardness and ensure that monovalent minerals in water do not lose. The nanofiltration process started in the mid-to-late 1980s and is a new pressure-driven physical separation process without phase change. The pore size of the nanofiltration membrane is larger than that of the ultrafiltration membrane but smaller than that of the reverse osmosis membrane. Therefore, when the nanofiltration membrane first came out, it was called a loose reverse osmosis membrane. The characteristic of nanofiltration ...

AI Technical Summary

Problems solved by technology

The characteristic of nanofiltration membrane is that it has a high rejection rate for divalent and multivalent ions, and its molecular weight cut-off is between 200-1000g·mol -1 , the rejection rate of monovalent ions is relatively low, and it is considered to be the best choice to solve this problem. However, the rejection rate of monovalent salts in commercial nanofiltration membranes is still about 50%, which inevitably leads to the loss of minerals.