Optimization of preparation conditions of a novel low-cost natural bio-sorbent from olive pomace and column adsorption processes on the removal of phenolic compounds from olive oil mill wastewater

Abstract Olive oil mill wastewater (OMWW) poses an undeniable environmental problem due to its high organic loads and phenolic compounds (PCs) content. This study determined the optimal conditions for preparing a new bio-sorbent from olive pomace (OP) and the adsorptive treatment of OMWW by this bio-sorbent. The activation reaction was performed with hydrogen peroxide. The results of the combination effect optimization of the three preparation variables: the activation temperature (°C) X1, the activation time (min) X2 and the impregnation ratio X3, are presented by the response surface methodology (RSM). The maximum adsorption capacity was obtained at activation time 300 min, temperature 80 °C and ratio equal to 6.2:1. The bio-sorbent was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffractometer (XRD). The adsorption process performance of this bio-sorbent was examined in batch and fixed-bed columns. An adsorption capacity of 446 mg g-1 has been achieved for 4000 mg L-1 concentration of PCs. The adsorption isotherm and kinetics were consistent with the Langmuir and pseudo-second-order models. Therefore, the Thomas model best fit the fixed bed column experimental data. The bio-sorbent gave a high desorption percentage of PCs, which was above 70% using HCl (0.1M).