Polyamide thin-film composite membrane on polyethylene porous membrane: Fabrication, characterization and application in water treatment

The ultrafiltration membranes fabricated by the non-solvent induced phase separation (NIPS) have been widely used as the supports of the polyamide thin film composite (PA TFC) membranes, although they are usually thick, low porosity, and poor chemical stability. Instead, thin polyethylene (PE) lithium battery microporous membrane with high surface porosity and connected pores is used as the support layer. PE membrane was pre-modified by the co-deposition of tannin and 3-aminopropyltriethoxysilane improving its hydrophilicity, and then a uniform and defect-free PA active layer was successfully fabricated by interfacial polymerization. The resultant membrane exhibited high filtration performances in the forward osmosis (FO) process (2 times higher water flux and 90% lower specific salt flux than the commercial HTI-TFC membrane), and efficient separation of NaCl and dyes in nanofiltration (NF) process, outstanding chemical stability and mechanical strength.