A Simple Process for Controlling the Separation Layer Structure of Nanofiltration Composite Membrane Assisted by Sericin

Nanofiltration plays an increasingly important role in liquid separation scenarios. Membrane preparation processes are important factors affecting the separation effect of nanofiltration. Protein molecules are often added to the preparation process of nanofiltration membranes to improve their precise separation performance. Sericin is a protein material with excellent water solubility, and it doesn't pose any additional harm to the environment. In this study, a sericin-assisted interfacial polymerization process for nanofiltration membrane was proposed to improve the membrane forming process. The sericin in aqueous solution improved the surface properties and pore structure of the separation layer. After careful verification, we believed that the nanofiltration membrane prepared using 1% piperazine, 0.1% 1,3,5-Benzenetricarbonyl trichloride, and 0.02% sericin had the best performance. It showed a rejection rate of Na 2 SO 4 99%, MgSO 4 98%, MgCl 2 95%, NaCl 27%, LiCl 20%. At 2 bar operating pressure, the permeate flux could be increased from 15 to 25 L m −2 h −1 . The Mg 2+ /Li + separation factor could reach 20, and the SO 4 2− /Cl − separation factor could reach 60. The nanofiltration membrane had excellent salt separation performance. It had a great application prospect in seawater desalination pretreatment, lithium extraction from salt lakes, and water softening.