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Enhanced Nitrobenzene reduction by zero valent iron pretreated with H2O2/HCl

Yang, Zhe, Ma, Xiaowen, Shan, Chao, Fang, Zhuoyao, Pan, Bingcai
Chemosphere 2018 v.197 pp. 494-501
aniline, corrosion, hydroxides, iron, iron oxides, liquids, nitroaromatic compounds, pH, reducing agents, wastewater, wastewater treatment
In this study a novel iron-based reducing agent of highly effective reduction toward nitrobenzene (NB) was obtained by pretreating zero valent iron (ZVI) with H2O2/HCl. During the H2O2/HCl pretreatment, ZVI undergoes an intensive corrosion process with formation of various reducing corrosion products (e.g., Fe²⁺, ferrous oxides/hydroxides, Fe3O4), yielding a synergetic system (prtZVI) including liquid, suspensions and solid phase. The pretreatment process remarkably enhances the reductive performance of ZVI, where a rapid reduction of NB (200 mg L⁻¹) in the prtZVI suspension was accomplished in a broad pH range (3–9) and at low dosage. Nitrosobenzene and phenylhydroxylamine are identified as the intermediates for NB reduction with the end-product of aniline. Compared with the virgin ZVI as well as another nanosized ZVI, the prtZVI system exhibits much higher electron efficiency for NB reduction as well as higher utilization ratio of Fe⁰. A rapid reduction of various nitroaromatics in an actual pharmaceutical wastewater further demonstrated the feasibility of the prtZVI system in real wastewater treatment.