The present investigation describes the adsorption capability of native and magnetic oxide (Fe3O4) impregnated bentonite clays for the adsorption of Cr(III) from aqueous solutions. The characterization of native bentonite as well as the impregnated bentonite was performed by PZC, SEM, BET, XRD and FTIR spectroscopy. The results proved that magnetized bentonite with high specific surface area provides high affinity and fast kinetics for the uptake of Cr(III). In the case of lower metal ion concentration in working solutions, the adsorption efficiency of the impregnated form was better than the native form. The effects of pH, contact time, temperature and initial metal ion concentration on overall adsorption efficiency were determined in detail. The equilibrium data was interpreted by linear forms of Langmuir, Fruendlich and Dubinin–Radushkevich isotherm models. Maximum adsorption capacity (Xm) for Cr(III) uptake was obtained as 1.25 and 1.28 mmol·g−1 for native and impregnated bentonite respectively. The apparent mean free energy of adsorption (E) determined from the DRK model was less than 8 kJ·mole−1 indicating that the Cr(III) adsorption on both adsorbents was physisorption in nature. Two different kinetic models, pseudo first and pseudo second order models were subjected to evaluate the kinetic data and reaction mechanism.

中文翻译：

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天然和磁性氧化物纳米颗粒 (Fe3O4) 浸渍膨润土作为去除 Cr(III) 的经济吸附剂

本研究描述了天然和磁性氧化物 (Fe3O4) 浸渍的膨润土从水溶液中吸附 Cr(III) 的吸附能力。天然膨润土和浸渍膨润土的表征通过 PZC、SEM、BET、XRD 和 FTIR 光谱进行。结果证明，具有高比表面积的磁化膨润土为 Cr(III) 的吸收提供了高亲和力和快速的动力学。在工作溶液中金属离子浓度较低的情况下，浸渍形式的吸附效率优于天然形式。详细确定了 pH、接触时间、温度和初始金属离子浓度对整体吸附效率的影响。平衡数据由朗缪尔的线性形式解释，Fruendlich 和 Dubinin-Radushkevich 等温线模型。对于天然和浸渍膨润土，Cr(III) 吸收的最大吸附容量 (Xm) 分别为 1.25 和 1.28 mmol·g-1。从 DRK 模型确定的表观平均吸附自由能 (E) 小于 8 kJ·mole-1，表明两种吸附剂上的 Cr(III) 吸附本质上都是物理吸附。两种不同的动力学模型，伪一级和伪二级模型用于评估动力学数据和反应机理。从 DRK 模型确定的表观平均吸附自由能 (E) 小于 8 kJ·mole-1，表明两种吸附剂上的 Cr(III) 吸附本质上都是物理吸附。两种不同的动力学模型，伪一级和伪二级模型用于评估动力学数据和反应机理。从 DRK 模型确定的表观平均吸附自由能 (E) 小于 8 kJ·mole-1，表明两种吸附剂上的 Cr(III) 吸附本质上都是物理吸附。两种不同的动力学模型，伪一级和伪二级模型用于评估动力学数据和反应机理。