(201g) Novel Thin Film Composite Membranes Fabricated from Upcycled Waste PVC Pipe Support Layer for Water Treatment

Nanofiltration (NF) thin-film-composite (TFC) membranes are well-known energy-efficient membranes for water treatment. Generally, these membranes are fabricated on support layer made of commercially available materials such as polyethersulfone (PES). On the other hand, plastic pollution is one of the main environmental concerns. Therefore, it is beneficial to upcycle waste plastic to a high-added-value product such as a membrane. In this work, we demonstrate the successful fabrication of the thin film composite (TFC) membranes with the support layer made from upcycled waste PVC pipe. The ultrafiltration (UF) support membranes were fabricated from waste PVC pipe (22 wt.% polymer in a mixture of N,N-Dimethylformamide and Tetrahydrofuran 3:2 (v/v)) via nonsolvent induced phase separation (NIPS) and then a polyamide layer was synthesized on the upcycled PVC membrane using interfacial polymerization. The physicochemical properties of the upcycled PVC membrane were compared and benchmarked with membranes fabricated using research-grade research (RG) PVC and commercial PES support layer. The results indicated that upcycled PVC pipe TFC membrane exhibited similar hydrophilicity (water contact angle around 30°), slightly more negative surface charge, and higher water permeability at 100 psi (17.2 LMH/bar) compared to RG TFC (14.5 LMH/bar) and PES TFC membranes (12.7 LMH/bar). Salt rejection of waste PVC pipe TFC membrane was also comparable to RG TFC and PES TFC as it achieved 88.9 % rejection for MgSO₄, 77.8 % rejection for CaCl₂, and 46.9% rejection for NaCl. Since the upcycled waste PVC pipe TFC membranes showed similar physiochemical properties and performance to the commercial RG PVC and PES TFC membranes, this shows that upcycling waste PVC pipe to membranes for water treatment can solve two biggest global challenges of plastic pollution and water treatment/purification simultaneously.