Resource utilization of sulfate-rich membrane concentrates via electrosynthesis of peroxydisulfate

Abstract

Developing an effective strategy for the high-value resource utilization of sulfate-rich membrane concentrates (SRMC) generated from wastewater reclamation remains a major challenge. This study demonstrates that the electrolysis of SRMC not only enables complete removal of organic pollutants but also permits the concurrent production of high-value peroxydisulfate (PDS). Using a fluorine-modified boron-doped diamond (BDD-F) electrode for PDS electrosynthesis, a 15 % higher Faraday efficiency was achieved compared to that of the pristine BDD electrode. The key intermediate for PDS formation was identified as HO•, and density functional theory calculations revealed that fluorine modification effectively suppresses the oxygen evolution reaction while promoting HO• generation. Approximately 230 mM of PDS was produced after 12 h of electrolysis, with the yield increasing linearly over time. When treating actual SRMC, complete organic mineralization was achieved within 5 h, accompanied by the production of ∼ 40 mM PDS. Notably, the PDS yield remained stable even after 15 cycles, indicating excellent electrode durability. The PDS derived from SRMC exhibited comparable performance in organic wastewater treatment to commercial one. These results confirm that electrolysis using a fluorine-modified BDD electrode represents a highly effective strategy for sulfate resource recovery from membrane concentrates.