Magnetic-activated carbon composites derived from sludge and steel converter slag for wastewater treatment

It is generally challenging to design efficient, low-cost, and environmentally friendly persulfate catalytic mate-rials for wastewater purification. We report a simple strategy to synthesize a steel converter slag-sludge carbon catalyst with steel converter slag as a template, suspended sludge as a precursor, and one-step pyrolysis. A persulfate activator was used to remove phenol and organic matter from actual wastewater leachate. The catalyst had a shell structure, a large surface area, abundant adsorption groups, and polymetallic catalytic capacity. The catalytic capacity depended on zero-valent iron (Fe-0), which effectively leached active Fe2+ composite to pro-duce hydroxyl and persulfate radicals by activating persulfate. The maximum phenol degradation was 94.5% in 55 min with 2 mM persulfate, 100 mg/L catalyst, and 20 mg/L phenol, which was 6 and 44 times greater than that of pure sludge carbon and steel converter slag, respectively. For actual wastewater leachate, the maximum removal rate of total organic carbon was 77.75% with 0.15 M persulfate, 50 g/L catalyst, and 1125 mg/L total organic carbon; all the fluorescent substances were removed. This work provides a new approach for designing persulfate catalysts derived from green resources. Further, our approach is practical for the treatment of wastewater that has high concentrations of organic material.