Aristotle University of Thessaloniki, Department of Chemistry, Division of Chemical Technology, 54124 Thessaloniki, Greece.
Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstr. 133, CH-8600 Dübendorf, Switzerland.
J Hazard Mater. 2015 Oct 30;297:1-7. doi: 10.1016/j.jhazmat.2015.04.038. Epub 2015 Apr 15.
The oxidation and removal of As(III) by commercially available micro-scale zero-valent iron (mZVI) was studied in aerated synthetic groundwater with initially 6.7 μM As(III) at neutral pH values. Batch experiments were performed to investigate the influence of ZVI and H2O2 concentrations on As(III) oxidation and removal. Oxidation and removal kinetics was significantly increased by increasing ZVI concentration or by adding H2O2 in micromolar concentrations slightly higher than that of initial As(III). Observed half-lifes for arsenic removal without added H2O2 were 81-17 min at ZVI concentrations of 0.15-2.5 g/L, respectively. X-ray absorption spectroscopy (XAS) confirmed that almost all As(III) was converted to As(V) after 2 h of reaction in the pH range 5-9. Addition of 9.6 μM H2O2 to 0.15 g/L ZVI suspensions diminished half-lifes for arsenic removal from 81 to 32 min and for As(III) oxidation from 77 to 8 min, i.e., by approximately a factor of 10. The increased rate of As(III) oxidation is attributable to enhanced formation of oxidants by the Fenton reaction with higher initial concentrations of H2O2. In practice, results of this study suggest that addition of small amounts (<1 mg/L) of H2O2 in various forms (e.g. stable and widely available Na-percarbonate) to water prior to treatment could significantly enhance As(III) oxidation and removal with ZVI.
研究了在中性 pH 值下，含有 6.7 μM 砷(III)的充气合成地下水中，市售微尺度零价铁 (mZVI) 对 As(III)的氧化和去除作用。进行了批量实验，以研究 ZVI 和 H2O2 浓度对 As(III)氧化和去除的影响。通过增加 ZVI 浓度或添加略高于初始 As(III)浓度的微量 H2O2，氧化和去除动力学显著提高。在没有添加 H2O2 的情况下，砷的去除半衰期分别在 ZVI 浓度为 0.15-2.5 g/L 时为 81-17 min。X 射线吸收光谱 (XAS) 证实，在 pH 值为 5-9 的范围内，反应 2 小时后，几乎所有的 As(III)都转化为 As(V)。向 0.15 g/L ZVI 悬浮液中添加 9.6 μM H2O2，将砷的去除半衰期从 81 min 缩短至 32 min，将 As(III)的氧化半衰期从 77 min 缩短至 8 min，即约缩短 10 倍。As(III)氧化速率的提高归因于初始 H2O2 浓度较高时，芬顿反应增强了氧化剂的形成。在实际应用中，本研究结果表明，在处理前向水中添加少量(<1 mg/L)各种形式的 H2O2(例如稳定且广泛可用的过碳酸钠)可显著提高 ZVI 对 As(III)的氧化和去除效果。
