Interfacial heterogeneous electro-Fenton membrane distillation for risk-controlled concentration of high-salinity coal-chemical wastewater

A heterogeneous electro-Fenton membrane distillation system is developed;. • Interfacial ·OH generation suppresses vapor-phase transfer of VOCs;. • High-salinity wastewater can be concentrated with controlled organic risk. High-salinity coal-chemical wastewater is challenging to manage because thermal concentration reduces wastewater volume but may simultaneously promote the carryover of volatile organics into the distillate and the enrichment of organics in the concentrating brine, thereby amplifying downstream risks. Here we develop a heterogeneous electro-Fenton membrane distillation (HEF-MD) process by integrating a Fe 3 O 4 -loaded membrane-based gas diffusion electrode (Fe 3 O 4 /Mem-GDE). This design couples oxygen delivery, in situ H 2 O 2 electro-generation, and surface-confined Fenton activation at the membrane-solution interface to establish an interfacial “reactive barrier”. Consequently, HEF-MD effectively suppresses vapor-phase transfer of representative volatile phenolics, achieving high rejection under conditions where conventional sweeping-gas MD exhibits low rejection or even enrichment of these compounds in the permeate. When applied to two real coal-chemical wastewaters, HEF-MD maintains stable vapor transport and high salt rejection while substantially improving distillate organic quality and mitigating organic build-up in the concentration brine, supporting a zero-liquid discharge operation. The system operates without chemical dosing or pH adjustment; when waste heat is available to drive MD, the incremental operating cost is dominated by electricity. Overall, these findings position HEF-MD as a practical, risk-controlled concentration strategy that couples desalination with in situ interfacial oxidation to suppress organic transfer, mitigate organic enrichment, and enable sustainable management of high-salinity industrial wastewaters. Download: Download high-res image (274KB) Download: Download full-size image