Cr(VI) has posed a serious risk for the environment and human beings because of its pollution and toxicity. It is essential to understand the equilibrium behavior of Cr(VI) in soils. In this study, the adsorption of Cr(VI) on fourteen soils was studied with batch experiments and quantitative modeling. The batch experiments included the adsorption edge and adsorption isotherm experiments, investigating the adsorption of Cr(VI) with varying soil properties, solution pH, and initial Cr(VI) concentrations. The experimental data were then modeled using the surface complexation models in Visual MINTEQ of CD-MUSIC by considering the adsorption of Cr(VI) and ions onto Fe (hydr)oxides and Al (hydr)oxides, and the Stockholm Humic Model and the fixed charge site model by accounting for the adsorption of the cations to soil organic matter and clay, respectively. Particularly, the modeling method of this study introduced an important parameter RO⁻ to account for the amount of soil organic matter irreversibly adsorbed on soil minerals. Overall, the model predicted reasonably well for the equilibrium partition of Cr(VI) under various conditions with a root-mean-square-error of 0.35 for the adsorption edge data and 0.19 for the adsorption isotherm data. According to the model calculations, ferrihydrite dominated the binding of Cr(VI) at pH of 3.0–7.0. The content of ferrihydrite and reactive soil organic matter was found to be the main factor influencing RO⁻. The modeling results help to understand and predict Cr(VI) adsorption on different soils and are beneficial to environmental risk assessment and pollution remediation.

中文翻译：

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预测六价铬在土壤上的吸附：土壤有机质竞争的作用

铬（VI），已构成对环境和人类的，因为它的污染和毒性的严重风险。了解土壤中Cr（VI）的平衡行为至关重要。在这项研究中，通过分批实验和定量建模研究了Cr（VI）在十四种土壤上的吸附。批处理实验包括吸附边和吸附等温线实验，研究了不同土壤性质，溶液pH和初始Cr（VI）浓度对Cr（VI）的吸附。然后通过考虑Cr（VI）的吸附，使用CD-MUSIC的Visual MINTEQ中的表面络合模型对实验数据进行建模。）和离子分别吸附到Fe（氢氧根）和Al（氢氧根）上，并通过考虑阳离子在土壤有机质和粘土上的吸附来确定斯德哥尔摩的Humic模型和固定电荷位点模型。特别是，这项研究的建模方法引入了一个重要参数RO ^-以占土壤有机质不可逆吸附在土壤矿物量。总体而言，该模型对于各种条件下的Cr（VI）的平衡分配具有较好的预测能力，其吸附边数据的均方根误差为0.35，吸附等温线数据的均方根误差为0.19。根据模型计算，水铁矿以Cr（VI）的pH值为3.0-7.0。的水铁矿和反应性土壤有机质含量被发现是影响RO的主要因素^- 。建模结果有助于理解和预测Cr（VI）在不同土壤上的吸附，有利于环境风险评估和污染修复。