ADSORPTION OF ZINC (II) AND NICKEL (II) FROM AQUEOUS SOLUTION USING SYZYGIUM AROMATICUM (CLOVES): KINETIC AND ISOTHERM STUDIES

Abstract

Present study deals with the adsorption of Zn(II) and Ni(II) onto cloves (Syzygium aromaticum) from aqueous solution under different process conditions. The adsorption was carried out in a batch process taking different concentrations of the metal ion in aqueous solution with variation in adsorbent dose, pH and agitation time. The solution initial pH values affected metal sorption. Over the pH range of 6 - 9, pH-related effects were significant. Meanwhile, at lower pH values the percentage of metal removal decreased. The sorption was found to decrease with increase in initial concentration and increases with increasing adsorbent dose. The equilibrium nature of Zn (II) and Ni (II) adsorption at different metal ion concentration were described by Langmuir, Tempkin and Freundlich Isotherm. The equilibrium data indicates the following order to fit the isotherms: Freundlich > Tempkin > Langmuir. In order to evaluate kinetic parameters Lagergren's first-order, pseudo-second-order, Elovich kinetic model and intra-particle diffusion models were explored. Among the kinetic models studied, the pseudo-second-order equation was the best applicable model to describe the sorption process. FTIR spectra of the adsorbent were recorded to explore the number and position of functional groups available for the binding of Zn (II) and Ni (II) ions of the studied adsorbent.