Fe3S4/Fe7S8-promoted degradation of phenol via heterogeneous, catalytic H2O2 scission mediated by S-modified surface Fe2+ species

Abstract

Enhancing center dot OH productivity via heterogeneous, catalytic H2O2 activation is a long-standing conundrum in H2O purification and thus requires the renovation of conventional reaction systems. The initial step in realizing advanced H2O2 decomposition via heterogeneous catalytic manner is the exploration of the solid capable of efficiently cleaving O-O bond inherent to H2O2 and minimizing the loss of catalytic species during vigorous reaction dynamics. While using phenol as a model compound for recalcitrants, this paper highlights the use of Fe3S4/Fe7S8 as a catalyst to enhance center dot OH productivity and thus promote phenol degradation via electro-Fenton reaction over conventional Fe2O3, Fe3O4, and other sulfide analogue (FeS2). Materials' characterizations and kinetic interpretation of reaction runs under controlled environments served to substantiate the benefits which were provided by Fe3S4/Fe7S8 during the reaction. Fe3S4/Fe7S8 incorporated greater amount of S-modified, surface-exposed Fe2+ sites to cleave H2O2 than FeS2. This improved catalytic consequence of Fe3S4/Fe7S8 (i.e., phenol conversion and initial reaction rate), as also evidenced by control runs detailing H2O2 decomposition in conjunction with tert-butyl alcohol-driven center dot OH scavenging. Filtration control runs as well as recycle runs were also used to verify that Fe3S4/Fe7S8 could heterogeneously catalyze H2O2 scission under the mild, adequate reaction environments, which were realized by the use of low electrical powers and the catalyst immobilized on a cathode.