Transforming Verbesina Encelioides Into an Efficient Biosorbent for Pb(II) Removal From Aqueous Systems

Abstract

Lead (Pb) is a toxic environment pollutant that needs effective removal treatment. In this study, a chemically modified leaves of Verbesina encelioides (CMLVEB) was prepared and evaluated for the remove of Pb(II) from aqueous system. The biosorbent was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) and Thermogravimetric Analysis (TGA). Experiments on batch biosorption showed that the highest removal efficiency (89%) was obtained at pH 4. The biosorption process followed pseudo-second-order kinetics (R² = 0.9915), indicating chemisorption, while equilibrium data were best described by the Langmuir isotherm with a maximum adsorption capacity of 119.63 mg g⁻¹. Moreover, the Dubinin–adushkevich (D–R) isotherm model suggested that Pb(II) biosorption mostly proceeded through an ion-exchange mechanism, with a mean adsorption energy of 9.15 kJ mol⁻¹. Thermodynamic parameters such as ΔH° = −16.29 kJ mol⁻¹, and ΔG° = −15.65 to −17.15 kJ mol⁻¹ indicated that the process is spontaneous and exothermic. The biosorbent demonstrated effective performance in real water samples and retained reusability over multiple cycles. These results emphasize that CMLVEB is an effective, low-cost, and environmentally friendly candidate to remove Pb(II) from polluted water systems.