Adsorption and polymerisation of silicic acid on ferrihydrite, and its effect on arsenic adsorption
Adsorption and polymerisation of silicic acid on ferrihydrite, and its effect on arsenic adsorption
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DOI：
10.1016/s0043-1354(99)00055-x
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发表时间：
1999-11
期刊：
影响因子：
12.8
通讯作者：
P. Swedlund
中科院分区：
文献类型：
--
作者：
P. Swedlund
硅酸 (H4SiO4) 和水铁矿之间的相互作用涉及吸附和聚合，并且对阴离子物质（例如砷的氧阴离子）的吸附具有显着影响。使用扩散层模型 (DLM)，根据实验吸附数据确定了 H4SiO4、As(V) 和 As(III) 吸附在水铁矿上的吸附常数。当总 Si 与 Fe 摩尔比 (Si(T)/Fe) < 0.1 时，可以考虑将硅酸作为单体进行吸附，并且可以使用 DLM 准确模拟 H4SiO4 对 As(III) 和 As(V) 吸附的抑制作用。在较高的 Si(T)/Fe 比率下，水铁矿表面上的 H4SiO4 聚合似乎变得越来越重要。然而，即使当 Si(T)/Fe=1.8 并且存在显着的 H4SiO4 聚合时，DLM 仍继续预测几乎所有观察到的 H4SiO4 对 As(III) 和 As(V) 吸附的影响，同时仅考虑 H4SiO4 吸附。这表明 H4SiO4 吸附对 As 吸附的抑制程度比 H4SiO4 聚合更大。
The interaction between silicic acid (H4SiO4) and ferrihydrite involves both adsorption and polymerisation, and has a significant effect on the adsorption of anionic species such as the oxyanions of arsenic. Using the diffuse layer model (DLM), the adsorption constants for H4SiO4, As(V), and As(III) adsorption onto ferrihydrite have been determined from experimental adsorption data. Silicic acid could be considered to adsorb as a monomer when the total Si to Fe mole ratio (Si(T)/Fe) was <0.1, and the inhibitory effect of H4SiO4on As(III) and As(V) adsorption could be accurately modelled using the DLM. At higher Si(T)/Fe ratios, H4SiO4polymerisation on the ferrihydrite surface appeared to become increasingly important. However, even when Si(T)/Fe=1.8 and there would have been significant H4SiO4polymerisation, the DLM continued to predict almost all of the observed effect of H4SiO4on As(III) and As(V) adsorption while taking only H4SiO4adsorption into account. This suggests that H4SiO4adsorption inhibits As adsorption to a greater degree than H4SiO4polymerisation.