Reductive sulfur mediated Fe2+ fixation and regeneration in valorizing waste activated sludge ash to Fe2+@S-doped sodalite material for emerging contaminants degradation: Performance and mechanism

Abstract

The leaching of ferrous iron (Fe²⁺) and its insufficient regeneration rate are common issues when using Fe²⁺-derived catalysts in Fenton-like reactions for removing emerging contaminants (ECs), leading to short lifespans and environmental risks. This study potentially addresses these challenges through establishing a reductive sulphur mediated Fe²⁺ fixation and regeneration mechanism within a waste-activated sludge-derived Fe²⁺@S-doped sodalite (FSZ) catalyst. The FSZ catalyst effectively activates peracetic acid to produce various reactive species (e.g. hydroxyl radicals, organic radicals and superoxide radicals, singlet oxygen, Fe(IV)), achieving over 99.5 % degradation of dexamethasone under optimised conditions. The S-Fe interaction in FSZ prevents 48.6 % of Fe²⁺ from leaching and reduces the generated Fe³⁺ accumulation, thereby extending the catalyst’s lifespan by 26.7 %. Given its superior ECs removal performance alongside effective aluminium and silicon recovery, this work offers a promising approach for contaminants removal, resource recovery, and material valorisation.