Liu Peng, Ptacek Carol J, Blowes David W, Landis Richard C
Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON N2L 3G1, Canada.
Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON N2L 3G1, Canada.
J Hazard Mater. 2016 May 5;308:233-42. doi: 10.1016/j.jhazmat.2016.01.007. Epub 2016 Jan 11.
Thirty-six biochars produced from distinct feedstocks at different temperatures were evaluated for their potential to remove mercury (Hg) from aqueous solution at environmentally relevant concentrations. Concentrations of total Hg (THg) decreased by >90% in batch systems containing biochars produced at 600 and 700 °C and by 40-90% for biochars produced at 300 °C. Elevated concentrations of SO4(2-) (up to 1000 mg L(-1)) were observed in solutions mixed with manure-based biochars. Sulfur X-ray absorption near edge structure (XANES) analyses indicate the presence of both reduced and oxidized S species in both unwashed and washed biochars. Sulfur XANES spectra obtained from biochars with adsorbed Hg were similar to those of washed biochars. Micro-X-ray fluorescence mapping results indicate that Hg was heterogeneously distributed across biochar particles. Extended X-ray absorption fine structure modeling indicates Hg was bound to S in biochars with high S content and to O and Cl in biochars with low S content. The predominant mechanisms of Hg removal are likely the formation of chemical bonds between Hg and various functional groups on the biochar. This investigation provides information on the effectiveness and mechanisms of Hg removal that is critical for evaluating biochar applications for stabilization of Hg in surface water, groundwater, soils, and sediments.
对36种由不同原料在不同温度下制备的生物炭进行了评估，以研究它们在环境相关浓度下从水溶液中去除汞（Hg）的潜力。在含有600和700°C制备的生物炭的批次系统中，总汞（THg）浓度降低了90%以上，而在300°C制备的生物炭中，THg浓度降低了40%-90%。在与基于粪便的生物炭混合的溶液中，观察到SO4(2-)浓度升高（高达1000 mg L(-1)）。硫X射线吸收近边结构（XANES）分析表明，未洗涤和洗涤后的生物炭中都存在还原态和氧化态的硫物种。从吸附了汞的生物炭获得的硫XANES光谱与洗涤后的生物炭相似。微X射线荧光映射结果表明，汞在生物炭颗粒上分布不均。扩展X射线吸收精细结构建模表明，在高硫含量的生物炭中，汞与硫结合，而在低硫含量的生物炭中，汞与氧和氯结合。汞去除的主要机制可能是汞与生物炭上各种官能团之间形成化学键。这项研究提供了有关汞去除效果和机制的信息，这对于评估生物炭在地表水、地下水、土壤和沉积物中稳定汞的应用至关重要。
