Engineered Aluminosilicate Frameworks for Targeted Purification of Contaminated Waters

This study investigates the development and optimization of acid-treated mineral-based frameworks, particularly clinoptilolite and mordenite, for the effective removal of toxic heavy metal ions, including Pb²⁺, Cd²⁺, and As³⁺, from aqueous media. The modification process employed hydrochloric acid solutions of varying molarity to enhance the adsorption capacity and surface reactivity of the zeolites. Structural and morphological transformations induced by acid treatment were thoroughly characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). These analytical techniques confirmed partial dealumination, an increase in surface area, and the emergence of new functional groups favorable for metal ion interaction. Batch adsorption experiments demonstrated that the modified zeolites achieved maximum lead removal efficiency exceeding 90%, while cadmium and arsenic removal also showed significant improvement. Kinetic modeling indicated that the adsorption process follows pseudo-second-order kinetics, highlighting chemisorption as the dominant mechanism. Thermodynamic analyses revealed that the reactions were spontaneous and endothermic. Importantly, the modified materials retained high removal efficiency over multiple adsorption-desorption cycles, supporting their application in continuous treatment systems. These findings position acid-activated natural zeolites as low-cost, eco-friendly, and highly effective adsorbents for the sustainable purification of contaminated water sources in industrial and environmental settings.