High-performance chlorinated polyvinyl chloride ultrafiltration membranes prepared by compound additives regulated non-solvent induced phase separation

Abstract

To enable wider deployment of ultrafiltration (UF) membrane technology, novel advanced membrane materials are still highly desired. Chlorinated polyvinyl chloride (CPVC) shares most of the outstanding features of polyvinyl chloride (PVC) and possesses improved thermal stability, indicating a promising material for UF membrane. To date, however, the separation performance of the current CPVC UF membranes is far below the requirements for application. In this study, propylene glycol and polyoxyethylene-20-sorbaitan monolaurate (Tween-20) were selected as compound additives to manipulate the structure and separation performance of CPVC membrane fabricated by the non-solvent induced phase separation process. The results demonstrated that the synergistic effect of compound additives led to instantaneous demixing to increase the ratio of polymer lean phase in the initial casting film, and the rapid precipitation fixed the phase separation structure immediately. Consequently, the prepared membranes possessed improved porosity and pore size uniformity. The obtained CPVC UF membranes exhibited a high pure water flux up to 955.2 L m-2 h-1·bar-1 with a BSA rejection above 95.0%, which is 11 times higher than CPVC membrane fabricated without additive and comparable to that of commercial UF membranes. In addition, thanks to the more uniform pore size distribution and smooth top surface, the obtained CPVC membranes also exhibited good antifouling performance. Moreover, the CPVC UF membrane showed good thermal stability and reuse performance, which would facilitate its post-functionalization and practical application.