State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Environ Sci Technol. 2010 Dec 1;44(23):9094-8. doi: 10.1021/es1024355. Epub 2010 Nov 5.
Removal and recovery of high levels of arsenic (As) in copper smelting wastewater present a great environmental challenge. A novel approach was investigated for the first time using TiO(2) for As adsorptive removal from wastewater and subsequent spent adsorbent regeneration and As recovery using NaOH. EXAFS results demonstrate that As(III), as the only As species present in the raw water, does not form an aqueous complex with other metal ions. An average of 3890 ± 142 mg/L As(III) at pH 1.4 in the wastewater was reduced to 59 ± 79 μg/L in the effluent with final pH at 7 in the 21 successive treatment cycles using regenerated TiO(2). Coexisting heavy metals including Cd, Cu, and Pb with concentrations at 369 mg/L, 24 mg/L, and 5 mg/L, respectively, were reduced to less than 0.02 mg/L. As(III) adsorption followed pseudosecond-order rate kinetics, and the adsorption behavior was described with the charge distribution multisite surface complexation model. Approximately 60% As(III) in the waste solution after the TiO(2) regeneration process was recovered by thermo vaporization and subsequent precipitation of sodium arsenite, as suggested by the EDX and XPS analysis. This "zero" sludge process sheds new light on successful As remediation technology for acidic metallurgical industry wastewater.
从铜冶炼废水中去除和回收高浓度砷（As）是一项重大的环境挑战。首次采用 TiO(2) 从废水中吸附去除 As，并使用 NaOH 对用过的吸附剂进行再生和回收 As，这是一种新颖的方法。EXAFS 结果表明，As(III)是原水中唯一存在的 As 物种，不会与其他金属离子形成水合络合物。在 21 个连续处理循环中，使用再生 TiO(2) 将废水的 pH 值为 1.4 时的平均 3890 ± 142 mg/L 的 As(III) 降低至最终 pH 值为 7 时的 59 ± 79 μg/L。共存的重金属，包括浓度分别为 369 mg/L、24 mg/L 和 5 mg/L 的 Cd、Cu 和 Pb，均降低至 0.02 mg/L 以下。As(III) 的吸附遵循拟二级速率动力学，吸附行为可用电荷分布多位点表面络合模型来描述。根据 EDX 和 XPS 分析，TiO(2) 再生过程后废水中约 60%的 As(III)通过热蒸发和随后的亚砷酸钠沉淀得到回收。该“零”污泥工艺为酸性冶金工业废水的成功砷修复技术提供了新的思路。
