Preparation of high temperature resistant polyamide composite nanofiltration membranes by thermally assisted interfacial polymerization

The temperature of interfacial polymerization (IP) and feed temperature both have importance effects on the structure and properties of polyamide thin film composite nanofiltration (TFC NF) membranes. This experiment involved preparing TFC NF membranes using IP at 25, 60, 80, and 100 °C, and their performance was evaluated in the range of 25 to 90 °C. Results showed that the membrane prepared at an IP temperature of 100 °C maintained more than 99% retention of divalent salts. The high temperature allowed the reaction between piperazine (PIP) and 1,3,5-benzoyl chloride (TMC) to become more complete and the degree of crosslinking increased, resulting in a thicker and denser defect-free polyamide layer. With increasing the temperature of the feed solution, the increase of pores sizes caused by swelling made the permeance increase by 2 ∼ 3 times, but the rejection rate of salt (Na2SO4, MgSO4) by TFC NF membranes prepared at 80 and 100 °C remained unchanged (>99%). In addition, the TFC NF membrane obtained by high-temperature IP has excellent anti-fouling and long-term stability. By adopting high-temperature IP, the TFC NF membranes exhibited excellent anti-fouling and long-term stability, making them an economical and versatile method for treating water in high-temperature environments.