Evaluation of mercury stabilization mechanisms by sulfurized biochars determined using X-ray absorption spectroscopy

JOURNAL OF HAZARDOUS MATERIALS

卷:347

Article

Liu, Peng^1,2  Ptacek, Carol J.²  Elena, Krista M. A.²  Blowes, David W.²  Gould, W. Douglas²  Finfrock, Y. Zou^3,4  Wang, Alana O.²  Landis, Richard C.⁵ 

[1] China Univ Geosci, Sch Environm Studies, 388 Lumo Rd, Wuhan 430074, Hubei, Peoples R China

[2] Univ Waterloo, Dept Earth & Environm Sci, 200 Univ Ave W, Waterloo, ON N2L 3G1, Canada

[3] Canadian Light Source Inc, Sci Div, 44 Innovat Blvd, Saskatoon, SK S7N 2V3, Canada

[4] Argonne Natl Lab, Adv Photon Source, CLS APS Sect 20, 9700 S Cass Ave, Argonne, IL 60439 USA

[5] I Du Pont de Nemours & Co, 974 Ctr Rd, Wilmington, DE 19805 USA

关键词: Biochar;    Mercury;    Polysulfur;    X-ray absorption spectroscopy;    Confocal X-ray micro-fluorescence imaging;   

DOI  :  10.1016/j.jhazmat.2017.12.051

来源: Elsevier

【 摘 要 】

The application of biochar to treat mercury (Hg) in the environment is being proposed on an increasing basis due to its widespread availability and cost effectiveness. However, the efficiency of Hg removal by biochars is variable due to differences in source material composition. In this study, a series of batch tests were conducted to evaluate the effectiveness of sulfurized biochars (calcium polysulfide and a dimercapto-related compound, respectively) for Hg removal; Hg-loaded biochars were then characterized using synchrotron-based techniques. Concentrations of Hg decreased by >99.5% in solutions containing the sulfurized biochars. Sulfur X-ray absorption near-edge structure (XANES) analyses indicate a polysulfur-like structure in polysulfide-sulfurized biochar and a thiol-like structure (shifted compared to dimercapto) in the dimercapto-sulfurized biochar. Micro-X-ray fluorescence (mu-XRF) mapping and confocal X-ray micro-fluorescence imaging (CXMFI) analyses indicate Hg is distributed primarily on the edges of sulfurized biochar and throughout unmodified biochar particles. Hg extended X-ray absorption fine structure (EXAFS) analyses show Hg in enriched areas is bound to chlorine (CI) in the unmodified biochar and to Sin sulfurized biochars. These results indicate that Hg removal efficiency is enhanced after sulfurization through the formation of strong bonds (Hg-S) with S-functional groups in the sulfurized biochars. (C) 2017 Elsevier B.V. All rights reserved.

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