Zhang Gaosheng, Qu Jiuhui, Liu Huijuan, Liu Ruiping, Wu Rongcheng
State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
Water Res. 2007 May;41(9):1921-8. doi: 10.1016/j.watres.2007.02.009. Epub 2007 Mar 23.
Arsenite (As(III)) is more toxic and more difficult to remove from water than arsenate (As(V)). As there is no simple treatment for the efficient removal of As(III), an oxidation step is always necessary to achieve higher removal. However, this leads to a complicated operation and is not cost-effective. To overcome these disadvantage, a novel Fe-Mn binary oxide material which combined the oxidation property of manganese dioxide and the high adsorption features to As(V) of iron oxides, were developed from low cost materials using a simultaneous oxidation and coprecipitation method. The adsorbent was characterized by BET surface areas measurement, powder XRD, SEM, and XPS. The results showed that prepared Fe-Mn binary oxide with a high surface area (265 m2 g(-1)) was amorphous. Iron and manganese existed mainly in the oxidation state +III and IV, respectively. Laboratory experiments were carried out to investigate adsorption kinetics, adsorption capacity of the adsorbent and the effect of solution pH values on arsenic removal. Batch experimental results showed that the adsorbent could completely oxidize As(III) to As(V) and was effective for both As(V) and As(III) removal, particularly the As(III). The maximal adsorption capacities of As(V) and As(III) were 0.93 mmol g(-1) and 1.77 mmol g(-1), respectively. The results compare favorably with those obtained using other adsorbent. The effects of anions such as SO4(2-), PO4(3-), SiO3(2-), CO3(2-) and humic acid (HA), which possibly exist in natural water, on As(III) removal were also investigated. The results indicated that phosphate was the greatest competitor with arsenic for adsorptive sites on the adsorbent. The presence of sulfate and HA had no significant effect on arsenic removal. The high uptake capability of the Fe-Mn binary oxide makes it potentially attractive adsorbent for the removal of As(III) from aqueous solution.
亚砷酸盐（As(III)）比砷酸盐（As(V)）毒性更强，且更难从水中去除。由于没有简单的方法能有效去除As(III)，因此总是需要一个氧化步骤来实现更高的去除率。然而，这会导致操作复杂且不具有成本效益。为克服这些缺点，利用同时氧化共沉淀法，从低成本材料中开发出一种新型的铁 - 锰二元氧化物材料，该材料结合了二氧化锰的氧化特性和氧化铁对As(V)的高吸附特性。通过BET比表面积测量、粉末XRD、SEM和XPS对吸附剂进行了表征。结果表明，制备的具有高比表面积（265 m2 g(-1)）的铁 - 锰二元氧化物为非晶态。铁和锰主要分别以+III和IV氧化态存在。进行了实验室实验以研究吸附动力学、吸附剂的吸附容量以及溶液pH值对砷去除的影响。批次实验结果表明，该吸附剂能将As(III)完全氧化为As(V)，对As(V)和As(III)的去除均有效，尤其是对As(III)。As(V)和As(III)的最大吸附容量分别为0.93 mmol g(-1)和1.77 mmol g(-1)。该结果与使用其他吸附剂获得的结果相比具有优势。还研究了天然水中可能存在的SO4(2-)、PO4(3-)、SiO3(2-)、CO3(2-)和腐殖酸（HA）等阴离子对As(III)去除的影响。结果表明，磷酸盐是与砷争夺吸附剂上吸附位点的最大竞争者。硫酸盐和HA的存在对砷的去除没有显著影响。铁 - 锰二元氧化物的高吸附能力使其成为从水溶液中去除As(III)的潜在有吸引力的吸附剂。
