Removal of Polyphenols from Olive Mill Wastewater by FPX 66 Resin: Part II. Adsorption Kinetics and Equilibrium Studies

Adsorption experiments of polyphenols from olive mill wastewater (OMW) using a cross-linked styrene– divinylbenzene polymer namely FPX 66 as a sorbent have been conducted. In particular the process of adsorption of phenolic compounds and carbohydrate derived from OMW by FPX 66 was rapid. A 68 and 60% reduction of polyphenols and carbohydrates, respectively was observed within the first 1 h. FPX 66 resin adsorption capacity increased by increasing polyphenol concentration values. At OMW-effluent-pH below 7.5 polyphenol removal from FPX 66 was high (77%) and for pH greater than 9.0 decreased (40%). Adsorption kinetics and equilibrium studies were carried out, fitting the equilibrium data to both Langmuir and Freundlich models. Batch adsorption models, based on the assumption of the pseudo-first-order, pseudo-second-order and intraparticle diffusion mechanism showed that kinetic data of the adsorption of polyphenols derived from OMW on FPX 66 resin followed the pseudosecond- order than the pseudo-first-order and intraparticle diffusion. Regeneration studies showed that low pH value was efficient for the recovery of phenolic compounds implying that the main mechanism of regeneration might be the chemisorption. These results of adsorption kinetics and equilibrium studies indicate the efficiency of FPX 66 resin as polyphenol sorbent from OMW effluent.