Upcycling Poly(ethylene terephthalate) by Fabricating Membranes for Desalination

Waste plastic upcycling is attracting increasing attention as a green and sustainable route for membrane fabrication. However, the existing literature in this domain is limited only to few commercial applications. This work presents the performance of membranes synthesized from recycled poly(ethylene terephthalate) (PET) for water desalination. PET extracted from waste plastic bottles was used to produce asymmetric membranes via nonsolvent-induced phase separation. The membrane performance was optimized by fine-tuning the PET, cosolvent, and additive concentration and the coagulation bath temperature. Increasing the PET content in the casting solution led to a decline in permeance across all experiments. A higher % composition of the volatile cosolvent in the solution improved the membrane selectivity. The addition of poly(ethylene glycol) as a pore-forming agent enhanced the permeance, and a higher NaCl rejection was observed when the coagulation bath temperature was decreased from 25 to 0 °C. Subsequently, PET membranes were also used as a support to fabricate thin-film composite membranes via interfacial polymerization of trimesoyl chloride and piperazine. These membranes demonstrated a remarkable permeance of 73 ± 4 L m^-2 h^-1 bar^-1 with a 33 ± 2% NaCl rejection. The findings of this study offer promising prospects for developing high-performance membranes using commercial plastic waste.