ABSTRACT
This study examined the sorption behaviour of Pb(II) and C.I. Acid Yellow 44 on Posidonia oceanica, an abundant Mediterranean biomass. A comparison with sorption onto cellulose extracted from the raw material was carried out to identify those site characteristics that play a predominant role in the adsorption of both dye and metal ions. Kinetic and equilibrium studies were performed for single and binary component systems, and the experimental data were analyzed by a non-linear method. The pseudo second-order kinetic model was successfully applied for both dye and metal retention onto sorbents in single and binary systems. Both sorbents were found to be more effective for lead than for Yellow 44 removal. However, lead sorption was more effective on raw P. oceanica suggesting that the metal ions are sorbed into the whole available biomass sites (cellulose and lignin). An opposite behaviour was reported for Yellow 44 sorption, which was found to be more effective on the extracted cellulose than raw P. oceanica. This finding proves that the only available sites for dye sorption are the cellulosic ones. The binary component experimental studies indicated competition between dye and lead for the available sites of raw P. oceanica. However, this competition was found to be less prevalent for sorption by cellulose extracted from raw P. oceanica suggesting that, in binary component systems, the cellulosic sites are equally available for both pollutants, the only limiting parameter being the size of the molecular sorbate. Langmuir and Freundlich isotherms were used to fit the experimental data using the non-linear method for parameter determination.
