Department of Environmental Sciences, The Connecticut Agricultural Experiment Station, New Haven, CT 06511, USA.
Department of Agronomy, Iowa State University, Ames, IA 50011, USA.
Water Res. 2018 Jun 15;137:153-163. doi: 10.1016/j.watres.2018.03.021. Epub 2018 Mar 9.
Arsenic (As) is toxic to human and is often found in drinking water in India and Bangladesh, due to the natural abundance of arsenides ores. Different removal procedures such as precipitation, sorption, ion exchange and membrane separation have been employed for removal of As from contaminated drinking water (CDW), however, there is a critical need for low-cost economically viable biochar modification methods which can enhance As sorption. Here we studied the effectiveness of zero-valent iron (ZVI)-biochar complexes produced by high temperature pyrolysis of biomass and magnetite for removing As from CDW. Batch equilibration and column leaching studies show that ZVI-biochar complexes are effective for removing As from CDW for the studied pH range (pH ∼7-7.5) and in the presence of competing ions. XPS As 3d analysis of ZVI-biochar complexes exposed to As in the batch and column studies show primarily As, indicating simultaneous oxidation of Fe° to Fe and reduction of As to As. SEM-EDS and XRD analyses show isomorphous substitution of As for Fe in neo-formed α/γ-FeOOH on biochar surfaces, which is attribute to co-precipitation. This study also demonstrates the efficacy of pyrolyzing biomass with low-cost iron ores at 900 °C to rapidly produce ZVI-biochar complexes, which have potential to be used for treatment of As CDW.
砷（As）对人体有毒，由于砷化物矿石的天然丰度，它经常存在于印度和孟加拉国的饮用水中。已经采用了不同的去除程序，例如沉淀、吸附、离子交换和膜分离，从受污染的饮用水（CDW）中去除 As，但是，迫切需要低成本的经济可行的生物炭改性方法，以增强 As 的吸附。在这里，我们研究了由生物质和磁铁矿在高温热解产生的零价铁（ZVI）-生物炭复合物从 CDW 中去除 As 的有效性。批平衡和柱浸出研究表明，ZVI-生物炭复合物在研究的 pH 范围（pH∼7-7.5）和存在竞争离子的情况下，可有效从 CDW 中去除 As。暴露于批处理和柱研究中 As 的 ZVI-生物炭复合物的 XPS As 3d 分析表明主要是 As，表明 Fe°同时被氧化为 Fe 和 As 被还原为 As。SEM-EDS 和 XRD 分析表明，在生物炭表面新形成的α/γ-FeOOH 中，As 取代 Fe 的同晶取代，这归因于共沉淀。这项研究还证明了在 900°C 下用低成本铁矿石热解生物质以快速生产 ZVI-生物炭复合物的功效，这些复合物有可能用于处理 As CDW。
