Sorption kinetics of Pb2+ and Cu2+ ions from aqueous solution by Nipah palm (Nypa fruticans Wurmb) shoot biomass

the sorption kinetics of pb2+ and cu2+ ions in aqueous solution by unmodified and mercaptoacetic acid modified biomass of nypa fruticans shoot has been investigated. the equilibrium sorption capacity of pb2+ and cu2+ was determined from the langmuir equation and found to be 15.59 mg/g and 21.85 mg/g for unmodified biomass and 52.86 mg/g and 66.71 mg/g for modified biomass at 30oc. the time dependent studies showed relatively rapid sorption of 5 - 10 min to reach equilibrium for both metal ions. a batch sorption model, based on the assumption of the pseudo-second-order mechanism, was applied to predict the rate constants (g mg-1 min-1), which were found to be 3.59 x 10-4 (pb2+) and 1.85 x 10-4 (cu2+) and 2.82 x 10-2 (pb2+) and 3.67 x 10-2 (cu2+) on unmodified and mercaptoacetic acid modified biomass respectively. the activation energy of the sorption of pb2+ and cu2+ on nypah palm reveals an endothermic process.