Application of novel phytosorbent to sequester chromium(VI) and lead(II) from aqueous phase: Optimization, equilibrium and kinetics

Abstract

AbstractThis study investigates the potential of Prosopis cineraria leaf powder (PCLP) as a biosorbent for removing heavy metal ions (HMIs) from aqueous solutions. The biosorption characteristics of PCLP were evaluated with respect to pH, contact time, initial concentrations, and biosorbent dosage. Equilibrium data were analyzed using Langmuir, Freundlich, Temkin, and Dubinin‐Radushkevich (D‐R) isotherm models. Langmuir isotherm demonstrated monolayer adsorption for Cr(VI) (R2 = 0.9876) and Pb(II) (R2 = 0.9990), with maximum adsorption capacities of 10.046 and 10.238 mg g−1, respectively. Kinetic analysis showed a good fit to the pseudo‐second‐order (PSO) model, with R2 values of 0.9979 for Cr(VI) and 0.9821 for Pb(II), indicating that H‐bonding and electrostatic interactions were the dominant adsorption mechanisms. Additionally, non‐linear regression analysis was performed to determine the best‐fitting equilibrium model and compared with linear isotherm and kinetic models. The results confirmed that the nonlinear method outperformed the linear method in isotherm analysis. Specifically, the nonlinear Temkin isotherm model exhibited stronger correlation with the experimental data, making it the most suitable model for fitting the equilibrium data. Conversely, the non‐linear pseudo‐second‐order models yielded comparable goodness of fit to the linear kinetic analysis results. Overall, the findings highlight PCLP as a promising, environmentally friendly, and cost‐effective biosorbent for the removal of toxic HMIs, contributing to sustainable environmental management.