An attractive agro-industrial by-product in environmental cleanup: Dye biosorption potential of untreated olive pomace

This research deals with the evaluation of highly available and cost effective waste biomass of olive pomace for the removal of reactive textile dye. RR198 from aqueous medium and a real effluent. The experiments were conducted to assess the effects of process variables such as initial pH, biosorbent dosage,contact time, temperature and ionic strength. The results showed that the highest dye biosorption capacity was found at pH 2 and the needed time to reach the biosorption equilibrium was 40 min with a biosorbent concentration of 3.0 g L-1. The sorption kinetics of dye was best described by the pseudo-second-order kinetic model. The equilibrium biosorption data were analyzed by Langmuir, Freundlich and Dubinin-Radushkevich isotherm models and the results from the isotherm studies showed that the RR198 biosorption process occurred on a homogenous surface of the biosorbent. The waste biomass of olive oil industry displayed biosorption capacities ranging from 6.05 x 10(-5) to 1.08 x 10(-4) mol g(-1) at different temperatures. The negative values of Delta G degrees and the positive value of Delta H degrees suggest that the biosorption process for RR198 was spontaneous and endothermic. Dye-biosorbent interactions were examined by FTIR and SEM analysis. Finally, high biosorption yield of olive waste for the removal of RR198 dye from real wastewater makes it possible that the olive pomace could be applied widely in wastewater treatment as biosorbent taking into account that no pretreatment on the solid residue is carried out. (C) 2008 Elsevier B.V. All rights reserved.