Engineering of Natural Clay-Based Materials to Eliminate Toxic Pb(II): Kinetic, Thermodynamic, and Adsorption Mechanism

Abstract

Climate change poses a threat to the water security by altering the precipitation patterns and other weather variables, which affect stream flow and freshwater availability. In this study, a soil and water assessment tool was used for the scarcity of blue and green water for future periods for sustainable management of freshwater resources away from lead pollution. Indeed, the presence of Pb2+ is an environmental problem and we have explored the use of natural phosphates (NP) as adsorbents for its elimination. The adsorbent NP was characterized by FTIR spectroscopy, scanning electron microscopy (SEM) and BET analysis. Batch adsorption experiments were performed to examine the effects of physical parameters namely the contact time, pH, stirring speed, temperature, adsorbent dose and initial Pb2+ concentration on the uptake capacity. Different models were used to fit the experimental data and to evaluate the kinetics, isotherms and thermodynamics of the Pb2+ adsorption. A high adsorption capacity of 66.66 mg/g was reached at 25°C and pH 6 and follows the Langmuir isotherm with a pseudo-second order kinetic. The adsorption is spontaneous and endothermic, indicating a structural exchange between NP and Pb2+ ions. Such results suggest that NP is a promising adsorbent for Pb2+ removal from wastewater