Preparation and characterization of a Syrian pumice-based ion exchanger for copper (II) ion adsorption

Heavy metal contamination of water resources, particularly by copper Cu(II) originating from industrial effluents, poses a significant threat to ecosystems and human health due to its toxicity and non-biodegradability. While adsorption is a widely recognized remediation technique, its economic viability is often hampered by the high cost of conventional adsorbents like activated carbon and synthetic ion-exchange resins. This economic constraint has driven the search for sustainable, low-cost alternative materials derived from abundant natural resources. Naturally occurring pumice, a volcanic rock with inherent porosity, has emerged as a promising candidate due to its global availability and low cost. However, a critical review of the literature reveals that the raw pumice typically exhibits limited adsorption capacity, restricting its practical application. Furthermore, while some studies have explored chemical activation to enhance its performance, the potential of Syrian pumice deposits remains significantly underexplored. There is a distinct lack of comprehensive studies that systematically investigate (a) a highly effective yet cost-effective chemical modification route for this specific pumice type, (b) a detailed analysis of its adsorption mechanisms beyond simple isotherm fitting, and (c) a rigorous economic assessment comparing it to incumbent technologies. This study addresses these critical gaps by presenting a novel, cost-effective adsorbent synthesized from locally sourced Syrian pumice for the efficient removal of Cu(II) ions. Through a simple alkaline modification, we produced a sodium hydroxide-treated pumice (P_Na) ion exchanger. The research quantitatively demonstrates an 18-fold increase in specific surface area and characterizes the material's exceptional adsorption performance across a wide range of operational parameters. We comprehensively analyze the kinetics, equilibrium isotherms, and thermodynamics to elucidate the hybrid adsorption mechanism. Crucially, this work demonstrates that the developed P_Na material achieves performance comparable to conventional adsorbents while incurring production costs 70-90% lower, thereby establishing Syrian pumice as a sustainable and economically transformative alternative for wastewater treatment.