Eleraky Mahmoud I, Razek Taha M A, Hasani Ibrahim W, Fahim Yosri A
Central Laboratories of the Egyptian Mineral Resources Authority, Cairo, Egypt.
Faculty of Graduate Studies and Environmental Research, Ain Shams University, Cairo, Egypt.
Sci Rep. 2025 Apr 16;15(1):13050. doi: 10.1038/s41598-025-95184-7.
This study evaluates the efficiency of alkali-activated Egyptian calcium bentonite, obtained from the El Alamein region in northern Egypt, for the removal of copper (Cu), lead (Pb), and nickel (Ni) from synthetic wastewater. The bentonite samples underwent a series of preparation steps, including crushing, ball milling, magnetic separation, acid treatment with 0.1N acetic acid, and alkali activation using 5% sodium carbonate (NaCO). Various analytical techniques, such as X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), cation exchange capacity (CEC) measurements, scanning electron microscopy (SEM), and free swelling analysis, were employed to characterize the materials. Absorption experiments were performed to examine the effects of pH, temperature, starting metal concentration, bentonite dose, and contact duration on heavy metal removal. The characterization results confirmed that montmorillonite was the predominant mineral in both the natural and activated bentonite samples. Adsorption studies indicated a significant improvement in heavy metal removal efficiency after activation. Under optimal conditions (pH 7, 1 g/L adsorbent dose, 120 min contact time, 20 mg/L initial metal concentration, and 20 °C), the maximum adsorption capacities of the activated bentonite were determined as 14 ± 0.03 mg/g for Cu, 13 ± 0.04 mg/g for Pb, and 12.2 ± 0.05 mg/g for Ni, exceeding those of the natural bentonite, which recorded capacities of 9.2 ± 0.04 mg/g, 9 ± 0.03 mg/g, and 8 ± 0.02 mg/g, respectively. Adsorption equilibrium data according to the Langmuir isotherm model, exhibiting high correlation values (R = 0.9979 for Cu, 0.9972 for Pb, and 0.9973 for Ni). Moreover, kinetic modeling demonstrated that the adsorption followed a pseudo-second-order mechanism, suggesting an intense chemisorption process. The thermodynamic analysis indicated that the adsorption process was spontaneous and endothermic, demonstrating enhanced adsorption at higher temperatures.
本研究评估了从埃及北部阿拉曼地区获得的碱活化埃及钙基膨润土对合成废水中铜（Cu）、铅（Pb）和镍（Ni）的去除效率。膨润土样品经过了一系列制备步骤，包括粉碎、球磨、磁选、用0.1N乙酸进行酸处理以及用5%碳酸钠（NaCO）进行碱活化。采用了各种分析技术，如X射线荧光光谱（XRF）、X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、阳离子交换容量（CEC）测量、扫描电子显微镜（SEM）和自由膨胀分析来表征这些材料。进行了吸附实验，以研究pH值、温度、初始金属浓度、膨润土剂量和接触时间对重金属去除的影响。表征结果证实蒙脱石是天然膨润土和活化膨润土样品中的主要矿物。吸附研究表明活化后重金属去除效率有显著提高。在最佳条件下（pH值7、吸附剂剂量1g/L、接触时间120分钟、初始金属浓度20mg/L和温度20°C），活化膨润土对铜、铅和镍的最大吸附容量分别确定为14±0.03mg/g、13±0.04mg/g和12.2±0.05mg/g，超过了天然膨润土，天然膨润土的吸附容量分别为9.2±0.04mg/g、9±0.03mg/g和8±0.02mg/g。根据朗缪尔等温线模型的吸附平衡数据显示出高相关值（铜的R = 0.9979、铅的R = 0.9972和镍的R = 0.9973）。此外，动力学建模表明吸附遵循准二级机制，表明存在强烈的化学吸附过程。热力学分析表明吸附过程是自发的且吸热的，表明在较高温度下吸附增强。
