El-Rayyes Ali, Hefnawy Mohamed, Refat Moamen S, Ogunbamowo Oyebola Elizabeth, Babatimehin Abidemi Mercy, Ngueagni Patrick T, Ofudje Edwin Andrew, Alsuhaibani Amnah Mohammed
Center for Scientific Research and Entrepreneurship, Northern Border University, Arar, 73213, Saudi Arabia.
Chemistry Department, College of Science, Northern Border University, Arar, Saudi Arabia.
Sci Rep. 2025 May 3;15(1):15526. doi: 10.1038/s41598-025-00361-3.
This study investigates the adsorption properties of arsenic (As(V)) from aqueous solutions using natural clay (NAC) and heat-treated natural clay (HTNAC), highlighting its novelty and significance as a sustainable approach to arsenic removal. The unique adsorption behaviors of the clays, enhanced by heat treatment, provide valuable insights into the influence of surface modification on adsorption efficiency. Characterization of the clays revealed significant changes in surface area, pore structure, and functional groups upon heat treatment, which improved their adsorption capacity. Functional groups such as Si-O-Fe, Si-Si-OH, Al-Al-OH, and Si-O-Al which were very useful for the arsenate ions uptake were identified from the Fourier-transform infrared (FT-IR) analysis, while X-ray diffraction (XRD) examination revealed peaks corresponding to illite, kaolin and quartz by the clay mineral. Utmost adsorption was attained at an interactive time of 150 and 180 min for HTNAC and NAC, pH of 5.0, temperature of 45 °C, and adsorbent dosage of 35 mg for NAC and 30 mg for HTNAC respectively. The data from equilibrium study of NAC matched the Langmuir model, whereas those from HTNAC matched the Freundlich model. The NAC kinetic data, correlate better to the first-order model, whereas the second-order model best described the kinetic data for HTNAC. The maximum sorption capacity found are 150.658 ad 197.662 mg/g for NAC and HTNAC respectively which revealed that the heat-treated clay exhibited superior performance compared to untreated clay, attributed to enhanced surface activity and reduced structural impurities. Thermodynamics values of ΔG at various temperatures were found to be in the range of - 26.58 to - 93.01 kJ/mol for NAC and - 32.17 to - 87.04 kJ/mol for HTNAC suggesting the sorption of As(V) to be feasible and a spontaneous process. This study underscores the importance of utilizing heat-treated natural clay as a low-cost, efficient, and environmentally friendly adsorbent for arsenic.
本研究考察了天然粘土（NAC）和热处理天然粘土（HTNAC）对水溶液中砷（As(V)）的吸附特性，突出了其作为一种可持续除砷方法的新颖性和重要性。经热处理增强的粘土独特吸附行为，为表面改性对吸附效率的影响提供了有价值的见解。粘土的表征显示，热处理后其表面积、孔隙结构和官能团发生了显著变化，从而提高了它们的吸附能力。通过傅里叶变换红外光谱（FT-IR）分析确定了对砷酸根离子吸收非常有用的官能团，如Si-O-Fe、Si-Si-OH、Al-Al-OH和Si-O-Al，而X射线衍射（XRD）检测显示粘土矿物对应伊利石、高岭土和石英的峰。HTNAC和NAC分别在150和180分钟的交互时间、pH值为5.0、温度为45℃以及NAC吸附剂用量为35mg、HTNAC吸附剂用量为30mg时达到最大吸附量。NAC平衡研究数据符合Langmuir模型，而HTNAC的数据符合Freundlich模型。NAC动力学数据与一级模型相关性更好，而二级模型最能描述HTNAC的动力学数据。NAC和HTNAC的最大吸附容量分别为150.658和197.662mg/g，这表明热处理后的粘土比未处理的粘土表现出更优异的性能，这归因于表面活性增强和结构杂质减少。发现不同温度下NAC的ΔG热力学值在-26.58至-93.01kJ/mol范围内，HTNAC的ΔG热力学值在-32.17至-87.04kJ/mol范围内，表明As(V)的吸附是可行的且是自发过程。本研究强调了利用热处理天然粘土作为一种低成本、高效且环保的砷吸附剂的重要性。
