Adsorption Isotherms, Kinetics and Thermodynamics Studies of Lead, Chromium and Cadmium Removal Efficiency from Aqueous Solution Using Magadiitic Aluminosilcate Nanozeolite

This study aimed to determine the adsorption Isotherms, kinetics and thermodynamic parameters of lead (Pb²⁺) chromium (Cr3+) and cadmium (Cd2+) ions from aqueous solutions using developed magadiitic aluminosilcate nanozeolite. The analyses were performed and evaluated by using liquid - solid phase extraction method with adsorbent system at optimal conditions. These conditions were, pH, adsorbent dosage, concentration, temperatures and contact time for adsorption of the analytes from the aqueous solutions onto the adsorbent were optimized at 5, 0.02 g, 25 ppm, 25°C and 15 minutes respectively. An Inductively Couple Plasma Emission spectrometer (ICPE – 9800 series Shimadzu) was used for the measurement of the emission intensities of Pb²⁺, Cr3+ and Cd2+ ions. Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models respectively were implemented to equilibrium results obtained. Experimental and theoretical monolayer adsorption capacities of the adsorbent adsorption of Pb²⁺, Cr3+ and Cd2+ ions by Langmuir Isotherm model also fitted the data well, with a maximum adsorption capacity of 37.88 mg/g, 8.53 mg/g and 9.56 mg/g respectively at 25°C. The most appropriate kinetics model from analysis of the adsorption mechanisms revealed that the process was best described by the Temkin Isotherm model, Pseudo-Second-Order kinetic model, indicated that chemisorption was the rate-limiting step. Thermodynamic values, Gibbs free energy (ΔGo), enthalpy changes (ΔHo), entropy change (ΔSo), were determined and assessed. Furthermore, thermodynamic studies confirmed that the adsorption of Pb²⁺, Cr3+ and Cd2+ ions onto the nanozeolite was a spontaneous and exothermic process. The Langmuir model’s high maximum adsorption capacity of 37.88 mg/g, for Pb²⁺, confirmed the material's strong affinity for lead ions.