锑矿冶炼区周边土壤吸附Sb (V)的行为研究

本文通过吸附平衡和动力学实验方法对Sb（V）在锑矿冶炼区周边土壤表面开展吸附行为研究，用常用的等温吸附模型和动力学吸附模型分别对等温吸附曲线和动力学吸附曲线进行拟合。结果表明：Langmuir与Freundlich模型对荒地土和林地土吸附Sb（Ⅴ）的等温吸附曲线均有较好的拟合效果，拟合系数R²0.988。荒地土对Sb（Ⅴ）的吸附能力大于林地土，其吸附量是林地土的2.9±0.2倍，这与Langmuir模型预测的该两种土壤的吸附倍数相当，荒地土表现出强烈吸附Sb（Ⅴ）的能力，尤其在锑浓度较高的体系中更为明显。结合土壤基本理化性质及矿物学特征，认为土壤秥粒、铁矿物和碳酸钙是影响土壤吸附Sb（V）的主要因素。有机质对土壤吸附Sb（Ⅴ）有一定促进作用，但这种影响只表现在Sb（Ⅴ）初始浓度低的条件下；而在Sb（Ⅴ）初始浓度高的条件下，有机质对土壤吸附Sb（Ⅴ）的影响不明显。土壤吸附Sb（Ⅴ）的过程分为快速吸附和慢速吸附两个阶段，快速反应发生在70 min以内。初始浓度低（0.01 mmol/L）的条件下，Elovich方程能够很好地拟合荒地土和林地土吸附Sb（V）的动态曲线；初始浓度高（2 mmol/L）的条件下，双常数方程对荒地土吸附Sb（V）的拟合效果较好，拟一级动力学方程和拟二级动力学方程则适用于拟合林地土吸附Sb（V）的过程。

Sorption Behaviors of Sb(V) on Soils from an Antimony Smelting Area

This study investigated sorption isotherms and kinetics of Sb(V) on different soils from an antimony smelting area. Results showed that sorption isotherms of wasteland and woodland soils fitted well with both Langmuir and Freundlich equations (R²≧0.988). Wasteland soils showed higher sorption abilities to Sb (V) than woodland soils, approximately 2.9±0.2 times higher. Wasteland soils showed a strong sorption ability of Sb(V), especially at high Sb(V) concentrations. By comprehensive considerations of basic physicochemical properties and mineralogical characteristics of soils, this study concluded that contents of clay, iron minerals and calcium carbonate are main controlling factors of Sb(V) sorption on these soils, while effects of organic matter (OM) was only notable in cases of low initial concentrations of Sb(V) but high initial concentrations. Sorption rates of Sb(V) in all treatments were fast during the first 70 min, and then slower for the rest experiment period. The sorption kinetics of Sb (V) on both wasteland and woodland soils could be described well by the Elovich equation when the initial concentration was low (C₀=0.01 mmol/L), but when the high initial concentration was high (C₀=2 mmol/L), the double constant equation fitted better for wasteland soils, while pseudo-first-order and pseudo-second-order models were more suitable for woodland soils.