Removal of Silver Ions (Ag+) from Aqueous Solutions Using Syrian Natural Zeolite N-79: Equilibrium and Thermodynamic Studies

Abstract

This study investigates the adsorption of silver ions (Ag⁺) from aqueous solutions using natural Syrian zeolites as an efficient, low-cost and environmentally sustainable adsorbent. Batch adsorption experiments were conducted to evaluate the effects of solution PH, contact time, adsorbent dosage, initial silver concentration and temperature on the on the adsorption performance. The adsorption equilibrium data were analyzed using the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. The Langmuir model provided the best fit to the experimental data, indicating monolayer adsorption with maximum adsorption capacity of 84.75mg/g. Under the optimized experimental conditions (PH=6-7, t=50min, m/v=0.2g/50ml, C_o=100mg/l) a maximum removal efficient of 96% was achieved. Thermodynamic analysis indicated that the adsorption was spontaneous and exothermic, as evidenced by the negative value of Gibbs free energy and enthalpy, furthermore, the negative entropy change (∆S) suggested reduced randomness. This findings demonstrate that natural Syrian zeolite is a promising adsorbent for the efficient removal of silver ions from aqueous solutions.