Synthesis of coal slime-based catalytic material for peroxymonosulfate activation through molten salt thermal treatment

Abstract

Coal slime-based peroxymonosulfate (PMS) catalytic materials were synthesized utilizing coal slime (CS) as raw material under the N2 atmosphere in this study. Raw and calcined coal slime were systematically characterized concerning morphologies, pore structures, chemical bonds, phase constituents, and defect density. Results show that after being calcinated with FeCl2∙4H2O at 750 °C, the specific surface area increased by nearly 21.0 times higher than that of CS. The addition of FeCl2∙4H2O has certain effect on the chemical bonds of calcined coal slime, i.e. the Fe elements can be fixed by the silicon aluminum skeleton with sekaninaite (Fe2Al4Si5O18) and aluminum iron silicon (Al0.5Fe3Si0.5, above 650 °C) generation, and the ID/IG values increase to 2.96 for CS-FeCl2-750. In addition, the degradation percentage of phenol by using CS-FeCl2 can achieve 100% in 25 min under optimized conditions. Furthermore, 1O2 plays a major role in phenol degradation, followed by •OH and SO4•− in the CS-FeCl2/PMS system from the quenching experiments and electron paramagnetic resonance results. Overall, the novel CS-FeCl2 material displays good application prospects in the field of effluent treatment, with efficient utilization of carbonaceous and silicon aluminum skeleton in coal slime.