خسرو محمدی

Biosorption of Pb(II) ions from aqueous solution by Gracilaria red algae as biomass was studied. IR spectroscopy was used for the identification of effective functional groups in the absorption process that carbonyl and amine groups were recognized as the more effective functional groups in the absorption process. The effects of effective parameters such as initial pH, temperature, initial lead concentration, biomass concentration, contact time and ionic strength on the Pb(II) biosorption were investigated. Two-parameter isotherm models such as Langmuir, Freundlich, Temkin and Dubinin–Radushkevich and also three-parameters isotherm models such as Sips and Fritz–Schlunder were used for description of the isotherms of lead uptake by the Gracilaria. The Dubinin–Radushkevich isotherm was determined as the best model for description of the absorption isotherm. The thermodynamic variables ?H?, ?S? and ?G? were calculated. Also both pseudo-first order and pseudo-second order models were tested for the evaluation of kinetic of the biosorption. Box-Behnken model in the Minitab software was used as the response surface methodology for the designation of experimental condition. A mathematical function for prediction of biosorption with respect to operating parameters was developed.