Zahid Mudasir, Doszhanov Yerlan, Saurykova Karina, Ahmadi Noorahmad, Bolatova Didar, Kurmanbayeva Meruyert, Aydarbek Akbope, Ihsas Rahmuddin, Seitzhanova Makpal, Akhmetzhanova Dana, Kerimkulova Almagul, Doszhanov Ospan
Faculty of Geography and Environmental Sciences, Al-Farabi Kazakh National University, Al-Farabi Ave. 71, Almaty 050040, Kazakhstan.
Department of Biology, Faculty of Education, Paktika University, Orgon Road, Paktika 2401, Afghanistan.
Molecules. 2025 Apr 30;30(9):2021. doi: 10.3390/molecules30092021.
In this paper, the modification of natural clinoptilolite and mordenite zeolites from Almaty using acid treatment is addressed for the purposes of improving adsorption performance and for drinking water purification. Structural chemical transformation was characterized by the use of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Scanning electron microscope (SEM) techniques. Acid treatment led to a partial dealumination that was responsible for an increase in the number of surface defects and micropores, improvement in ion exchange capacity, and selectivity toward heavy metals. Additionally, modifications greatly enhance the uptake capacities of Pb, Cd, and As. The clinoptilolite post-modification removal efficiencies reached 94%, 86%, and 84%, respectively, while mordenite zeolites achieved 95%, 90%, and 87% removal efficiencies, respectively. The enhancement of performance was related to the increase in surface area and active sites for ion exchange, verified from analysis of the Brunauer-Emmett-Teller (BET) surface area. The use of different Bhatt and Kothari methods has revealed that adsorption processes followed Langmuir isotherm models for Pb and Cd, whereas As adsorption was better described by the Freundlich isotherm model. However, second-order kinetics indicate that chemisorption was the dominant mechanism. Such evidence indicates spontaneity and an endothermic process, as shown from thermodynamic studies. Results showed that modified zeolites indeed had a high degree of reusability, with over 80% of the adsorption capacity retained even after five cycles. Acid-modified zeolites can provide cheaper, greener methods of purification, generating only negligible secondary waste when compared to conventional methods of water purification, for example, activated carbon and membrane filtration. Results from this study proved that modified clinoptilolite and mordenite zeolites have the potential for sustainable heavy metal treatment in drinking water purification systems.
本文针对来自阿拉木图的天然斜发沸石和丝光沸石进行酸处理改性，目的是提高吸附性能并用于饮用水净化。通过X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）和扫描电子显微镜（SEM）技术对结构化学转变进行了表征。酸处理导致部分脱铝，这使得表面缺陷和微孔数量增加、离子交换容量提高以及对重金属的选择性增强。此外，改性极大地提高了对铅、镉和砷的吸附能力。斜发沸石改性后的去除效率分别达到94%、86%和84%，而丝光沸石的去除效率分别达到95%、90%和87%。性能的提高与通过布鲁诺尔-埃米特-泰勒（BET）表面积分析验证的离子交换表面积和活性位点的增加有关。使用不同的Bhatt和Kothari方法表明，铅和镉的吸附过程遵循朗缪尔等温线模型，而砷的吸附用弗伦德里希等温线模型能更好地描述。然而，二级动力学表明化学吸附是主要机制。如热力学研究所显示的，这些证据表明该过程具有自发性且是吸热过程。结果表明，改性沸石确实具有高度的可重复使用性，即使经过五个循环，仍保留超过80%的吸附容量。与传统的水净化方法（如活性炭和膜过滤）相比，酸改性沸石可以提供更便宜、更环保的净化方法，产生的二次废物可忽略不计。本研究结果证明，改性斜发沸石和丝光沸石在饮用水净化系统中具有可持续处理重金属的潜力。
