Cerium oxide modified activated carbon as an efficient and effective adsorbent for rapid uptake of arsenate and arsenite: Material development and study of performance and mechanisms
Cerium oxide modified activated carbon as an efficient and effective adsorbent for rapid uptake of arsenate and arsenite: Material development and study of performance and mechanisms
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DOI：
10.1016/j.cej.2016.09.068
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发表时间：
2017-05
影响因子：
15.1
通讯作者：
Yang Yu;Chengyu Zhang;Liming Yang;J. Chen
中科院分区：
文献类型：
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作者：
Yang Yu;Chengyu Zhang;Liming Yang;J. Chen
地下水中砷酸盐和亚砷酸盐的共存对人类造成很大的风险。本研究的目的是开发一种氧化铈改性活性炭并研究其去除砷物质的性能。该吸附剂是通过一步溶剂热法制备的。 FESEM-EDX分析表明氧化铈主要包覆在碳表面。热重分析表明吸附剂上存在丰富的羟基。零电荷点约为6.0。砷物质的吸收很大程度上受溶液 pH 值的影响。 pH 5 时 As(V) 和 As(III) 的最大吸附容量分别为 43.60 和 36.77 mg-As/g。在吸附动力学研究中观察到快速吸附导致 30 分钟内达到 90% 的最终吸收，其性能优于其他报道的吸附剂；通过孔扩散模型获得了更好的实验数据拟合。磷酸盐的存在对吸附表现出最显着的干扰。腐殖酸、硫酸盐和碳酸盐的存在造成了有限的干扰，特别是在低浓度水平下。根据X射线光电子能谱分析结果，吸附剂上近90%的铈元素为Ce(IV)。 Ce(IV) 的高氧化还原电位导致 As(III) 在去除过程中部分氧化，从而提高了 As(III) 的吸收。吸附剂上的羟基与砷物质之间的配体交换在砷的吸收中起着关键作用。
Co-existence of arsenate and arsenite in groundwater poses a great risk to humans. The objective of this study was to develop a cerium oxide modified activated carbon and to study its performance for removal of arsenic species. The adsorbent was prepared by a one-step solvothermal process. The FESEM-EDX analysis showed that the cerium oxide was mainly coated on the carbon surface. The thermal gravimetric analysis indicated the abundant presence of hydroxyl groups on the adsorbent. The point of zero charge was approximately 6.0. The uptake of arsenic species was highly affected by solution pH. The maximum adsorption capacities of As(V) and As(III) at pH 5 were 43.60 and 36.77 mg-As/g, respectively. A rapid adsorption causing 90% of ultimate uptake in 30 min was observed in the adsorption kinetics study, which outperformed other reported adsorbents; the better fitting of the experimental data was obtained by a pore diffusion model. The presence of phosphate exhibited the most significant interference on the adsorption. A limited interference was caused by the existence of humic acid, sulphate and carbonate, in particular at low concentration levels. Based on the results from the X-ray photoelectron spectroscopy analysis, nearly 90% of cerium element on the adsorbent was Ce(IV). The high redox potential of Ce(IV) was responsible for the partial oxidation of As(III) during the removal, which improved the As(III) uptake. The ligand exchange between hydroxyl groups on the adsorbent and arsenic species played a key role in the uptake of arsenic.