Removal of divalent nickel from aqueous solutions using Carissa carandas and Syzygium aromaticum: isothermal studies and kinetic modelling

Biosorptive removal of divalent nickel from aqueous solution using Carissa Carandas and Syzygium aromaticum was investigated in batch mode and the observations were correlated with the pH variation, agitation time, dose of the adsorbent and initial metal ion concentration in the solution. In the course of this study Sorption efficiency of C. carandas leaf powder found higher than that of S. aromaticum under identical experimental conditions. The maximum adsorption capacities estimated for Ni(II) through Freundlich isotherm model were 3.76 and 2.96 mg/g for C. carandas and S. aromaticum, respectively. In kinetic studies the correlation coefficient (R-2 = 0.99) for the pseudo-second order kinetics modal was higher than that of pseudo-first order kinetics model and the calculated value of q(e) for the pseudo-second order kinetic model resulted very close to the experimental value, which indicates that it fits well with the equilibrium data for Ni(II) sorption from aqueous solutions on biosorbents.