Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions, College of Environment and Planning, Henan University, Kaifeng 475004, China; Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; National Demonstration Center for Environmental and Planning, Henan University, Kaifeng 475004, China.
Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions, College of Environment and Planning, Henan University, Kaifeng 475004, China.
J Environ Sci (China). 2020 Aug;94:147-160. doi: 10.1016/j.jes.2020.03.006. Epub 2020 Apr 30.
The ubiquitous arsenic in groundwater poses a great risk to human health due to its environmental toxicity and carcinogenicity. In the present work, a new adsorbent, δ-MnO modified activated carbon, was prepared, and its performance for the uptake of arsenate and arsenite species from aqueous solutions was investigated by batch experiments. Various techniques, including FESEM-EDX, p-XRD, XPS and BET surface area analysis, were employed to characterize the properties of the adsorbent and the arsenic adsorption mechanisms. The results showed that δ-MnO covered on the surface and padded in the pores of the activated carbon. Adsorption kinetic studies revealed that approximately 90.1% and 76.8% of As(III) and As(V), respectively, were removed by the adsorbent in the first 9 hr, and adsorption achieved equilibrium within 48 hr. The maximum adsorption capacities of As(V) and As(III) at pH 4.0 calculated from Langmuir adsorption isotherms were 13.30 and 12.56 mg/g, respectively. The effect of pH on As(V) and As(III) removal was similar, and the removal efficiency significantly reduced with the increase of solution pH. Arsenite oxidation and adsorption kinetics showed that the As(V) concentration in solution due to As(III) oxidation and reductive dissolution of MnO increased rapidly during the first 12 min, and then gradually decreased. Based on the XPS analysis, nearly 93.3% of As(III) had been oxidized to As(V) on the adsorbent surface and around 38.9% of Mn(IV) had been reduced to Mn(II) after As(III) adsorption. This approach provides a possible method for the purification of arsenic-contaminated groundwater.
地下水中普遍存在的砷由于其环境毒性和致癌性，对人类健康构成了巨大威胁。本研究制备了一种新型吸附剂δ-MnO 改性活性炭，通过批量实验研究了其从水溶液中摄取砷酸盐和亚砷酸盐的性能。采用 FESEM-EDX、p-XRD、XPS 和 BET 比表面积分析等多种技术对吸附剂的性质和砷吸附机制进行了表征。结果表明，δ-MnO 覆盖在活性炭的表面并填充在其孔隙中。吸附动力学研究表明，吸附剂在最初的 9 小时内分别去除了约 90.1%和 76.8%的 As(III)和 As(V)，48 小时内达到吸附平衡。在 pH 4.0 下，根据 Langmuir 吸附等温线计算的 As(V)和 As(III)的最大吸附容量分别为 13.30 和 12.56 mg/g。pH 对 As(V)和 As(III)去除的影响相似，去除效率随溶液 pH 的增加而显著降低。砷酸盐氧化和吸附动力学表明，在最初的 12 分钟内，由于 As(III)氧化和 MnO 的还原溶解，溶液中 As(V)的浓度迅速增加，然后逐渐降低。根据 XPS 分析，在吸附剂表面上近 93.3%的 As(III)被氧化为 As(V)，在 As(III)吸附后约 38.9%的 Mn(IV)被还原为 Mn(II)。该方法为砷污染地下水的净化提供了一种可能的方法。
