Mobilization of arsenite by competitive interaction with silicic acid
Mobilization of arsenite by competitive interaction with silicic acid
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DOI：
10.2136/sssaj2005.0101
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发表时间：
2006-01-01
影响因子：
2.9
通讯作者：
Eick, MJ
中科院分区：
文献类型：
--
作者：
Luxton, TP;Tadanier, CJ;Eick, MJ
由于砷的急性毒性，即使是一小部分砷进入用作饮用水来源的地表水和地下沃茨，也会对人类健康造成重大风险。在这里，我们评估的动员亚砷酸盐[As（III）]从铁（氢）氧化物矿物针铁矿（α-FeOOH）通过竞争性置换的柠檬酸，一种天然存在的和普遍存在的无机配体。研究了在pH值为3-11的条件下，针铁矿对草酸和As（III）的吸附行为.在天然沃茨的二氧化硅浓度特征（3-30 mg L-1）和代表高污染水平（3.75-7.5 mg L-1）的初始溶液As（III）浓度下收集单离子吸附和zeta电位数据。竞争吸附的情况下，无论是Si或As（M）吸附到针铁矿表面，然后与其他吸附平衡，也进行了检查。无论pH值或另外的情况下，在总山梨酸盐浓度小于反应性表面位点密度，没有观察到任何含氧阴离子的竞争性置换。然而，在总的山梨酸盐浓度大于反应表面的网站密度，作为（III）的吸附减少了10至15%，在整个pH值范围内，无论另外的情况下，导致在水的浓度远远超过目前（10 μ g L-1）饮用水的最大污染物水平。使用电荷分布多位点表面络合（CD-MUSIC）模型的单离子吸附和zeta电位数据的表面络合建模被用来计算一组合适的表面吸附平衡常数为As（III）和草酸吸附，这是用来描述竞争吸附的情况。竞争性吸附数据和CD-MUSIC模型预测的比较，在总山梨酸盐浓度大于反应表面针铁矿的密度，表明二氧化硅是竞争性取代As（III）。
Due to the acute toxicity of As, mobilization of even a small fraction of As into surface and ground waters used as a source for drinking water represents a substantial risk to human health. Here we evaluate the mobilization of arsenite [As(III)] from the Fe-(hydr)oxide mineral goethite (alpha-FeOOH) through competitive displacement by silicic acid, a naturally occurring and ubiquitous inorganic ligand. The adsorption behaviors of silicic acid and As(III) on goethite were investigated at environmentally relevant pH (3-11). Single ion adsorption and zeta-potential data were collected at silica concentrations characteristic of natural waters (3-30 mg L-1) and initial solution As(III) concentrations representative of high levels of contamination (3.75-7.5 mg L-1). Competitive adsorption scenarios with either Si or As(M) sorbed first to the goethite surface, followed by equilibration with the other sorbate, were also examined. No competitive displacement of either oxyanion was observed at total sorbate concentrations less than reactive surface site density, regardless of pH or addition scenario. However, at total sorbate concentrations greater than reactive surface site density, As(III) adsorption was reduced by 10 to 15% over the entire pH range regardless of addition scenario, resulting in aqueous concentrations well in excess of current (10 mu g L-1) drinking water maximum contaminant levels. Surface complexation modeling of single ion adsorption and zeta-potential data using the Charge Distribution Multisite Surface Complexation (CD-MUSIC) model was used to calculate an appropriate set of surface adsorption equilibrium constants for As(III) and silicic acid adsorption, which was used to describe the competitive adsorption scenarios. Comparison of competitive adsorption data and CD-MUSIC model predictions, at total sorbate concentration greater than reactive surface site density of goethite, suggest that silica is competitively displaced by As(III).