Hydrophobic block copolymer ultrafiltration membranes for anti-scaling durable membrane distillation crystallization

Due to the inherent insensitivity to salt concentration, membrane distillation (MD) has emerged as a promising technology for high-salinity wastewater treatment. However, scaling remains a critical challenge hindering the widespread application of MD. This study proposes a solution through the development of triblock polystyrene-block-polydimethylsiloxane-block-polystyrene (SDS) membranes with precisely engineered pore structures that effectively address this limitation. The results demonstrate that controlled pore size reduction, which was achieved via selective swelling fabrication, significantly mitigates both surface scaling and intra-pore crystallization. The SDS membrane shows remarkable performance stability under diverse high-salinity conditions, including those high-salinity solutions containing common inorganic contaminants such as CaSO₄. Furthermore, when implemented in membrane distillation-crystallization (MDC), the SDS membrane maintains stable performance under a continuous operation for 168 h with saturated NaCl feed, successfully producing high-purity water while simultaneously recovering salt crystals. These results demonstrate that controlled pore size reduction represents an effective strategy to mitigate membrane scaling while maintaining performance stability, offering significant advantages for industrial implementation in zero liquid discharge systems treating high-salinity wastewater.