Mohammad Ramezani Moghaddam - School of Chemical Engineering, Fasculty of Engineering, University of Tehran, Iran
Shohreh Fatemi - School of Chemical Engineering, Fasculty of Engineering, University of Tehran, Iran
Alireza Keshtkar - Atomic Energy Organization of Iran, North Kargar Ave. Tehran, Iran

Biosorption of heavy metals could be an effective process to remove heavy metal ions from aqueous solutions. This process strongly depends on the pH of aqueous media. The previous studies on lead ion removal by Cystoseira indica algae have revealed that pH of 5.5 could be the optimal condition for the effective removal of Pb2+ from water. In this study, pretreated Cystoseira indica with CaCl2, was used as biosorbent for Pb2+ removal from aqueous solution. The equilibrium sorption experiments at two levels of pH (pH 3 and pH 5.5) were conducted for various Pb+2 concetration, at room temperature. Six isotherm models were examined to correlate the equilibrium biosorption experimental data, and four error functions (ERRSQ, HYBRD, MPSD and AARE) were used to verify the accuracy and precision of the results. It was concluded that pH dependent Reddlich-Peterson isotherm model would be the best model among selected isotherm equations in the range of studied pH.

Biosorption, Lead ions removal, Cystoseira indica, pH dependent isotherm models