Depositing sericin on partially degraded polyamide reverse osmosis membrane for restored salt rejection and simultaneously enhanced resistance to both fouling and chlorine

Abstract

This work reports the repairing of partially degraded polyamide TFC RO membrane for restored salt rejection and simultaneously enhanced resistance to both chlorine and fouling through adopting an in-situ, simple and upscalable approach of cross-flow filtration of sericin aqueous solution followed by flushing with de-ionized water. The attachment of sericin molecule on membrane surface was confirmed by XPS analysis and was found to be effective in recovering membrane reverse osmosis performance. The membrane with a degraded salt rejection higher than 94.0% exhibited a restored salt rejection the same as or a little higher than that of the new membrane (before chlorination). The deposition of sericin was also found to make membrane surface smoother and more hydrophilic and negatively charged under neutral condition, and thus endow the restored membrane with enhanced fouling resistance to bovine serum albumin compared with the new membrane. Furthermore, the chlorine exposure experiments demonstrated that the restored membrane with the coating of sericin exhibited better resistance to chlorine compared to the new membrane. The simplicity and good reproducibility of the restoration treatment procedure and the satisfactory performance stability of the restored membrane reveal that the in-situ restoration approach of present work is attractive for practical applications.