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 Pb²⁺, Cd²⁺, and As³⁺. 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 Pb²⁺ and Cd²⁺, whereas As³⁺ 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.

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 XRD, FTIR, and SEM techniques. Acid treatment led to a partial dealumination that was responsible for the increase in number of surface defects and micropores, improvement in ion exchange capacity and selectivity toward heavy metals. Additionally, modifications greatly enhance the uptake capacities of Pb²⁺, Cd²⁺ and As³⁺. 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 of surface area and active sites for ion exchange, verified from analysis of BET surface area. The use of different Bhatt and Kothari methods has revealed that adsorption processes followed Langmuir isotherm models for Pb²⁺ and Cd²⁺, whereas As³⁺ 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 compare 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.

Due to its admirable adsorption capacity, activated carbon is used widely as an adsorbent. Thus, it proves to be an effective adsorbent for environmental remediation, water purification, and air cleaning. The present work takes a perspective on the synthesis, characterization, and adsorption behavior of activated carbon from walnut shell, an environmental waste material of huge renewable source. High-surface-area activated carbon with high adsorption capacity was prepared by chemical activation based on the utilization of phosphoric acid. The synthesized AC is characterized by using sophisticated techniques: SEM, FTIR, BET, and XRD. Batch adsorption tests using methylene blue (MB) were carried out to measure adsorption efficiency, with recorded maximum adsorption capacity reaching 450 mg/g. These results highlight the walnut shell activated carbon as an efficient, economical, and green adsorbent. This shows the feasibility of this material on the industrial scale for applications to purify water and air: a safe method for treating agricultural waste besides fighting against environmental pollution. Results reveal that even moderate conditions lead to a very porous architecture with BET surface area higher than 1200 m²/g. FTIR and XRD illustrate functional groups and the presence of amorphous carbon structures, corresponding to SEM images of a well-defined porous network. These results underline that WSAC can serve as an effective, sustainable, and economic adsorbent that can find applications in extra-large environmental applications, elaborating a circular economy concept converting agricultural waste into resources for pollution elimination.