A crystallinity control strategy for controllable Heterogeneous-Homogeneous reaction and catalytic performance in wet-mechanochemical synthesized FeS2 Fenton system

Abstract

In heterogeneous Fenton system, the Heterogeneous-Homogeneous reaction type induced by surface-bonded or dissolved catalytic center plays a vital role in determining Fenton performance. However, how to directionally control the reaction type with facile method still remains challenging. Herein, a novel crystallinity control strategy based on wet-mechanochemical synthesis combined with heat-treatment was applied to synthesize FeS2 nanoparticles with different crystallinity. The different crystalline FeS2 based Fenton system exhibited superior sulfamethoxazole removal performance at wide pH range (5.6–11) with •OH as dominating reactive oxygen species. The relative degradation contribution of homogeneous and heterogeneous Fenton reaction was semi-quantitatively evaluated, and the relationship between crystallinity indexes of FeS2 and degradation kinetic constants was established. It’s found that FeS2 crystallinity was directly correlated with its degradation efficiency, which first increased and then declined with crystallinity increasing. Crystallinity control strategy effectively determined dominating reaction type (homogeneous or heterogeneous) and further regulated catalytic performance in FeS2 Fenton system based on the interaction of specific surface area and Fe2+ dissolution ability. This work provides a novel crystallinity control strategy to build a correlative bridge among crystallinity, dominating reaction type and catalytic performance in FeS2 Fenton system.