Adsorptive behavior, isothermal studies and kinetic modeling involved in removal of divalent lead from aqueous solutions, using Carissa carandas and Syzygium aromaticum

This study is focused on the biosorption of lead(II) ion onto surface of Carissa carandas and Syzygium aromaticum biomass from aqueous solution. The operating parameters, pH of solution, biomass dosage, contact time, initial metal ion concentration, and temperature considerably affect the biosorption efficiency of Pb(II). Biosorbent C. carandas leaf powder showed higher sorption efficiency than that of biosorbent S. aromaticum powder under identical experimental conditions. It was observed that the lead(II) removal percentage was found highest of 95.11% for C. carandas and 91.04% for S. aromaticum at contact period of 180 min. Also, it was observed that the regression coefficient (R2 = 0.99) for the pseudo-second-order kinetic model is higher in comparison with the pseudo-first-order kinetic model and the calculated value of qe for the pseudo-second-order kinetic model is very close to the experimental value, which indicates that it fits well with the equilibrium data for Pb(II) sorption from aqueous solutions on biosorbents. Also, the adsorption of Pb(II) onto C. carandas was best described by the Freundlich isotherm model