BIOSORPTION OF Cd2+, Pb2+ AND Zn2+ FROM AQUEOUS SOLUTION BY SWEET POTATO LEAF: KINETIC, THERMODYNAMIC AND ISOTHERMAL STUDIES

Abstract

Biosorption is a promising technique for the removal of heavy metals from industrial wastewater and effluents by applying low cost biosorbents. In this study, the potential of sweet potato leaf as low cost adsorbent for the removal of Cd2+, Pb2+ and Zn2+ from aqueous medium was investigated. The influence of each of pH, contact time, initial metal ion concentration, temperature and adsorbent dosage was studied in batch experiment. The leaf was characterised using FT-IR spectroscopy and Scanning Electron Micrograph (SEM).  The experimental data were evaluated with four kinetic models (pseudo first-order, pseudo second-order, Elovich and Intraparticle diffusion) and four isotherm models (Freundlich, Langmuir, Temkin and D-R). The adsorption process was feasible and endothermic in nature. The functional groups involved in the biosorption process were OH, and C-O. The results obtained showed that the biosorption was temperature, time, pH, metal ion concentration and adsorbent dosage dependent. The kinetic studies showed that biosorption of the metal ions on the biomass followed pseudo-first-order and the Freundlich isotherm best fit the biosorption equilibrium. Keywords: biosorption, sweet potato, kinetics, isotherms