Sorption of Yellow 59 on Posidonia oceanica, a non-conventional biosorbent: Comparison with activated carbons

Posidonia oceanica, an endemic marine magnoliophyta found in the Mediterranean Sea, is used as a biosorbent for dye wastewater treatment. The ability of P. oceanica to remove the dye C.I. Acid Yellow 59 from an aqueous solution was compared to that of two commercial activated carbon forms: powdered (PAC) and granular (GAC) activated carbon. The effect of initial pH, mass concentration, contact time and initial dye concentration were investigated for the three sorbents. Equilibrium uptake was found to be pH dependent and maximum uptake was observed at an acid pH (2-3) for all materials. Kinetic studies for initial dye concentration of 20, 50 and 100 mg L-1 showed that dye uptake followed the pseudo-second order model for all materials and equilibrium was reached in 10, 400 and 600 min for PAC, GAC and P. oceanica, respectively. The equilibrium data tend to fit Freundlich isotherm model for all materials, the best retention of C.I. Acid Yellow 59 was found to be on PAC followed by P. oceanica and then GAC. This comparative study indicates that sorption onto P. oceanica is an effective, cheaper alternative for dye removal. (C) 2008 Elsevier B.V. All rights reserved.