Mackinawite (FeS) activation of persulfate for the degradation of p-chloroaniline: Surface reaction mechanism and sulfur-mediated cycling of iron species
Among the numerous iron-based materials for persulfate (PS) activation, mackinawite (FeS) particles have gained considerable interest as a ubiquitous natural mineral due to their high reactivity. However, the iron and sulfur co-mediated reaction mechanism of PS activation by FeS remains ambiguous. In this study, FeS was applied as a catalyst to activate PS for p -chloroaniline (PCA) degradation and mineralization over a wide initial pH range (3.0–11.0). The reaction was found to follow pseudo-first-order kinetics, with rate constants ranging from 0.0044 to 0.0144 min −1 . The reaction mechanism was elucidated by electron spin resonance (ESR) and quenching studies. A heterogeneous activation mechanism, in which surface Fe(II) species activated PS to produce OH ads and SO 4 − ads , controlled by surface reaction and diffusion was proposed, whereas OH free and SO 4 − free diffusing from the FeS surface were mainly responsible for PCA degradation. The sulfur-mediated cycling of iron species was investigated by comparing PS activation by zero-valent iron (ZVI) and FeS, exogenous Fe(III) addition and X-ray photoelectron spectroscopy (XPS). The results suggested that Fe(II) and S(-II) experienced independent oxidations and that S(-II) species could regenerate Fe(II) from Fe(III) at the FeS surface. Therefore, the S(-II)-promoted Fe(II)/Fe(III) cycle resulted in less PS decomposition but a higher PCA mineralization efficiency. The findings of this study elucidated the novel surface activation mechanism of PS by FeS and provided useful information for utilizing FeS to remediate contaminated water.
危险品化学品经营许可证（带存储）