Dynamic interactions between sulfidated zerovalent iron and dissolved oxygen: Mechanistic insights for enhanced chromate removal

WATER RESEARCH

卷:135

Article

Shao, Qianqian¹  Xu, Chunhua¹  Wang, Yahao¹  Huang, Shasha¹  Zhang, Bingliang¹  Huang, Lihui¹  Fan, Dimin²  Tratnyek, Paul G.³ 

[1] Shandong Univ, Sch Environm Sci & Engn, Jinan 250100, Shandong, Peoples R China

[2] US EPA, Oak Ridge Inst Sci & Educ, Off Superfund Remediat & Technol Innovat, Arlington, VA 22202 USA

[3] Oregon Hlth & Sci Univ, OHSU PSU Sch Publ Hlth, 3181 SW Sam Jackson Pk Rd, Portland, OR 97239 USA

关键词: Sulfidation;    Zerovalent iron;    Aerobic;    Reductive sequestration;    Fe(II) regeneration;    Corrosion enhancement;   

DOI  :  10.1016/j.watres.2018.02.030

来源: Elsevier

【 摘 要 】

Recent research on contaminant removal by zerovalent iron (ZVI) has evolved from investigating simple model systems to systems that encompass increased dimensions of complexity. Sulfidation and aerobic conditions are two of the most broadly relevant complications. Combining these two, this study investigated the dynamic interactions between sulfidated microscale ZVI and dissolved O-2, for removal of Cr(VI), a model contaminant for metals and metalloids. The results show that the coupling of sulfidation and oxygenation significantly improves Cr removal, which is attributed to enhanced Fe(II) production that resulted from accelerated corrosion of Fe(0). The Cr(VI) removal rate increased with increasing O-2 saturation from 0% to 100% but showed a bimodal dependence on the S/Fe ratio. At the optimal S/Fe ratio, the ZVI exhibits a highly porous surface morphology, which, according to prior literature on sulfur induced corrosion, promotes corrosion. In addition, a novel time series correlation was developed between aqueous Fe(II) and Cr(VI) based on data collected in the presence and absence of 1,10-phenanthroline, to probe for changes of reductants during the reaction time course. The analysis indicated that Fe(0) was responsible for the initial small amount of Cr(VI) removal, which then transitioned to a phase controlled by surface Fe(II). The slopes of the time series correlations during the latter phase of the reaction vary with experimental conditions but are mostly much higher than the theoretical stoichiometric ratio between Cr(VI) and Fe(II) (i.e., 0.33), indicating that Fe(II) regeneration contributes significantly to Cr removal. (C) 2018 Elsevier Ltd. All rights reserved.

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