Study on the application of nanofiltration membrane in the SO42− removal of sodium sulfate-type brine

For the application in alkali industries, the SO₄^2- removing of sodium sulfate type brine is the key step. Compared with other denitration methods, membrance method has no phase change and save power. In this paper, two type membranes (NF40-4040, NF90-4040) were used to treat the high concentration brine, the experiment results were as follows: the rejection rate of NF40-4040 membrane for sulfate was 3.4% and for chloride was 58.2% with the temperature of 40°C and the pressure of 1.6MPa; the rejection rate of NF90-4040 membrane for sulfate was 76.8% and for chloride was 27.6%, which was much higher; Ion rejection rate was related to the membrane type, ion concentration, pressure, temperature and other factors. The lower the ion concentration, and the higher the pressure, the higher rejection rate will be.