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首页> 外文期刊>Journal of Environmental Science and Health. A, Toxic/Hazardous Substances & Environmental Engineering >Adsorption-Desorption Characteristics of Lead in Variable Charge Soils
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Adsorption-Desorption Characteristics of Lead in Variable Charge Soils

机译：可变电荷土壤中铅的吸附-解吸特性

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摘要

Adsorption-desorption processes of Pb at contaminated levels in two variable charge soils were investigated. The red soil (RAR) developed on the Arenaceous rock (clayey, mixed siliceous thermic typic Dystrochrept) adsorbed more Pb~(2+) than the red soil (REQ) derived from the Quaternary red earths (clayey, kaolinitic thermic plinthite Aquult). The maximum adsorption values (X_m) that were obtained from the simple Langmuir model were 52.6 mmolPb~(2+) kg~(-1) soil and 29.9 mmolPb~(2+) kg~(-1) soil, respectively, for the RAR and REQ. Adsorption of Pb~(2+) decreased soil pH by 1.10 unit for the RAR soil and 1.21 unit for the REQ soil at the highest loading. The adsorption equilibrium pH of RAR was higher than that of REQ at the same Pb~(2+) concentration. The distribution coefficient (K_d) of Pb in the soils decreased exponentially with increasing Pb~(2+) loading. Most of the adsorbed Pb~(2+) in the soils was not desorbed in the 0.01 mol L~(-1) NaNO_3 solution. After five successive extractions with NaNO_3, only 0-11% of the total adsorbed Pb~(2+) in the RAR soil was desorbed and the corresponding value of the REQ soil was 0-19%, indicating that the RAR soil had a greater affinity for Pb~(2+) than the REQ soil at the same Pb~(2+) loading. Different mechanisms might be involved in Pb~(2+) adsorption/desorption at different levels of Pb~(2+) loading and between the two soils.
机译：研究了两种可变电荷土壤中铅在污染水平下的吸附-解吸过程。砂质岩石（黏土，混合的硅质热典型Dystrochrept）上发育的红壤（RAR）比第四纪红土（黏土，高岭石热软质亚硫酸盐Aquault）产生的红壤（REQ）吸附更多的Pb〜（2+）。从简单的Langmuir模型获得的最大吸附值（X_m）分别为52.6 mmolPb〜（2+）kg〜（-1）土壤和29.9 mmolPb〜（2+）kg〜（-1）土壤。 RAR和REQ。在最高负荷下，RAR土壤的Pb〜（2+）吸附使土壤pH降低1.10单位，REQ土壤降低1.21单位。在相同的Pb〜（2+）浓度下，RAR的吸附平衡pH高于REQ。铅在土壤中的分布系数（K_d）随铅（2+）负荷的增加呈指数下降。土壤中大部分吸附的Pb〜（2+）在0.01 mol L〜（-1）NaNO_3溶液中均未解吸。用NaNO_3连续萃取五次后，RAR土壤中吸附的总Pb〜（2+）中只有0-11％解吸，而REQ土壤的对应值为0-19％，表明RAR土壤具有更大的吸附能力。在相同的Pb〜（2+）负荷下，土壤对Pb〜（2+）的亲和力大于REQ土壤。在两种土壤之间，不同水平的Pb〜（2+）负载下Pb〜（2+）的吸附/解吸可能涉及不同的机制。

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