Interfacial adsorption for efficient removal of Fe3+, Mn2+, Ni2+, Cd2+, and Sr2+ from wastewater using synthetic clinoptilolite via single-treatment approach

A highly effective synthetic clinoptilolite (SCP) was developed and assessed for its potential in the simultaneous removal of Cd 2+ , Ni 2+ , Mn 2+ , Sr 2+ , and Fe 3+ from an aqueous solution. The present work explored the influences of SCP dosage, initial metal ion concentrations, temperature, contact time, and pH value on the adsorption performances of these metal ions. The results revealed exceptionally high adsorption capacities, reaching 2000, 1720, 1875, 1510, and 22 mg/g for Ni 2+ , Fe 3+ , Cd 2+ , Mn 2+ , and Sr 2+ , respectively. The specific surface area of SCP increased from 31.4 to 44.7 m 2 /g after five cycles. The adsorption mechanism and structure assessment were elucidated by XRD patterns and SEM images, showing that the Fe 3+ adsorption conformed to the Langmuir isotherm, while that of Mn 2+ , Cd 2+ , Sr 2+ , and Ni 2+ followed the Freundlich isotherm model with the adsorption kinetics best described by the pseudo-2nd-order kinetic model. Thermodynamic parameters showed endothermic behavior for Cd 2+ , Ni 2+ , Mn 2+ , and Sr 2+ , exothermic for Fe 3+ , and spontaneity for all metals except Sr 2+ . SCP retained over 90 % of its adsorption capacity after five regeneration cycles, maintaining structural integrity under thermal, acidic, and recycling conditions. These findings highlight SCP’s robust characteristics, reusability, and potential for sustainable heavy metal removal from wastewater.