Khoddam Mohammad Ali, Norouzbeigi Reza, Velayi Elmira, Cavallaro Giuseppe
Nanomaterials and surface technology research Laboratory, School of Chemical, Petroleum and Gas Engineering, Iran University of Science and Technology, P.B. 16765-163, Narmak, Tehran, Iran.
Department of Chemical Engineering, Faculty of Engineering, Azarbaijan Shahid Madani University, P.O.Box: 537517-1379, Tabriz, Iran.
Sci Rep. 2024 Sep 16;14(1):21629. doi: 10.1038/s41598-024-72885-z.
Arsenic contamination in aqueous media is a serious environmental problem, especially in developing countries. In this research, the Box-Behnken response surface methodology was used to optimize the most relevant variables affecting arsenic adsorption on the ZnO-halloysite surface, including temperature, adsorbent dosage, pH, contact time, and As (III) initial concentration. The regression analysis indicated that the experimental data were appropriately fitted to a quadratic model with the adjusted R-squared value (R) of 0.982 for As(III) adsorption capacity and a linear model with R of 0.931 for As(III) removal. The p-values for both adsorption capacity and removal efficiency were below 0.05, with F-values of 116.91 and 115.58, respectively, supporting the model's validity. The optimum conditions for maximum removal of As(III) were determined through numerical and graphical optimization using the desirability function. It was found that the optimum conditions for adsorption were pH = 7.99, contact time of 3.99 h, As(III) initial concentration of 49.96 mg/L, and adsorbent dosage of 0.135 g/40 ml. The accuracy of the optimization procedure was confirmed by a confirmatory experiment, which showed a maximum arsenic removal of 91.31% and an adsorption capacity of 12.63 mg/g under optimized conditions. Moreover, XPS analysis was performed at different pH levels to investigate the As (III) adsorption mechanism. The results demonstrated that As(III) adsorption occurs at acidic and neutral pH levels. On the other hand, when pH is increased to 8, As (III) oxidizes to As (V), and then adsorption occurs.
水介质中的砷污染是一个严重的环境问题，尤其是在发展中国家。在本研究中，采用Box-Behnken响应面方法优化影响ZnO-埃洛石表面砷吸附的最相关变量，包括温度、吸附剂用量、pH值、接触时间和As(III)初始浓度。回归分析表明，实验数据与二次模型拟合良好，As(III)吸附容量的调整R平方值(R)为0.982，As(III)去除率的线性模型R为0.931。吸附容量和去除效率的p值均低于0.05，F值分别为116.91和115.58，支持模型的有效性。通过使用期望函数进行数值和图形优化，确定了最大程度去除As(III)的最佳条件。结果发现，吸附的最佳条件为pH = 7.99、接触时间3.99小时、As(III)初始浓度49.96 mg/L和吸附剂用量0.135 g/40 ml。通过验证实验证实了优化程序的准确性，该实验表明在优化条件下最大砷去除率为91.31%，吸附容量为12.63 mg/g。此外，在不同pH水平下进行了XPS分析，以研究As(III)的吸附机制。结果表明，As(III)在酸性和中性pH水平下发生吸附。另一方面，当pH值增加到8时，As(III)氧化为As(V)，然后发生吸附。
