Efficient Bromine Recovery from Fly Ash Waste Salt via Electro-Oxidation Coupled with Membrane Absorption

Fly ash waste salt (FAWS) generated from e-waste incineration is rich in valuable bromine resources, but its complex composition poses dual challenges in safety and economics for traditional resource recovery methods. In response, this study developed a functionally integrated nanofiltration–electro-oxidation–membrane absorption (NF–EO–MA) process for bromine recovery from FAWS. In this integrated design, NF removes multivalent interfering species, EO enables chlorine-gas-free bromide conversion, and MA selectively extracts generated bromine from the hypersaline chloride matrix. This strategy eliminates the use of hazardous chlorine gas (Cl 2 ) in conventional processes, utilizing clean electrical energy to drive the in situ generation of active halogens, and couples it with a superhydrophobic polytetrafluoroethylene (PTFE) hollow fiber membrane contactor for targeted, low-energy bromine separation. Experimental results demonstrate that following efficient NF rejection of 98.2% of sulfate impurities, the integrated system achieved a Br – conversion efficiency of 98.8% without external Cl 2 addition under optimized conditions (80 mA·cm –2, pH 10.5, 60 min). Kinetic studies confirmed that the MA process follows an apparent first-order kinetic model, yielding a single-pass bromine extraction efficiency of 68.6% under optimal operating conditions. Ultimately, the integrated process successfully produced a NaBr-rich absorbent with 95.2% NaBr purity and a high-purity NaCl-rich raffinate with 99.3% NaCl purity. These results demonstrate the feasibility of converting hazardous FAWS into value-added salt products, providing a promising route for solid waste valorization and strategic bromine resource recovery.