Abstract

Heavy metals, such as nickel, due to their toxicity and stability, are harmful to human health. Natural bentonite and its acid-activated forms have been employed as adsorbents for the adsorption of Ni²⁺ ions from wastewater. In this process, natural bentonite was first activated with sulfuric acid so that its adsorption properties, such as specific surface area, cation exchange capacity, and adsorption capacity could be increased. The samples were then characterized through XRD, XRF, FTIR, and BET Analyses. The adsorption of Ni²⁺ was studied by pH, reaction temperature, and shaking rate experiments. BET studies showed that the activated samples had multimodal pore size distributions in micro and mesopores and the average pore diameters were around 4 nm. The XRD patterns of the acid-activated samples showed the intensity of Opal-A peaks was not significantly affected but the peaks corresponding to the calcite mineral decreased and even disappeared after the acid-activation. The result of the pH effect on the adsorption showed the low nickel adsorption in the acidic region due to the high amount of H₃O⁺. The results showed that the concentration of acid and time were very important factors in acid activation and the uptake of Ni²⁺ could be successful through acid activation.

摘要

重金属，如镍，由于其毒性和稳定性，对人体健康有害。天然膨润土及其酸活化形式已被用作吸附剂，用于吸附废水中的 Ni ²⁺离子。在此过程中，天然膨润土首先用硫酸活化，使其比表面积、阳离子交换容量和吸附容量等吸附性能得到提高。然后通过 XRD、XRF、FTIR 和 BET 分析对样品进行表征。Ni ^2+的吸附通过pH、反应温度和振荡速率实验研究。BET 研究表明，活化样品在微孔和中孔中具有多峰孔径分布，平均孔径约为 4 nm。酸活化样品的 XRD 图谱显示 Opal-A 峰的强度没有显着影响，但对应方解石矿物的峰在酸活化后减少甚至消失。pH对吸附的影响结果表明，由于H ₃ O ⁺含量高，在酸性区域对镍的吸附较低。结果表明，酸的浓度和时间是酸活化的重要因素，通过酸活化可以成功吸收Ni ^{2+ 。}