Closed-Loop Recycling of End-of-Life Poly(Ether Sulfone) Membranes: Upcycling Waste into Bisphenol S via a...

The rapid growth of membrane-based water treatment has led to rising consumption of poly(ether sulfone) (PES) membranes and increasing concerns over their end-of-life disposal. Existing approaches, such as aggressive cleaning or solvent dissolution, can extend membrane lifespan but do not fundamentally resolve the environmental risks posed by discarded membranes. This study introduces a catalyst-free hydrolysis route that enables selective depolymerization of waste PES and recovery of a high-value product, bisphenol S (BPS). Under hydrothermal conditions of 250 °C for 10 h, BPS was detected at 8.8 mg/L, confirming a specific degradation pathway from PES to BPS. Increasing temperature intensified polymer chain mobility and promoted bond cleavage, while the presence of hydroxide ions further accelerated depolymerization. Further investigations demonstrated the efficacy of the hydrothermal treatment under optimized conditions. At 250 °C with 0.8 mol OH^-/g PES, nearly complete degradation was achieved within 6 h, yielding BPS at 94.1%. Techno-economic analysis and life-cycle assessment demonstrated the economic viability and environmental benefits of this process. Overall, this study provides a practical, sustainable pathway for upcycling end-of-life PES membranes and supports the transition toward resource recovery and circular economy practices.