Phenolic compounds adsorption from olive oil industry effluent using experimental design methodology: screening and central composite design optimization Scientific paper

Abstract

The experimental design methodology was investigated to model and optimize the adsorption process for removing phenolic compounds (PC) from olive mill wastewater (OMW) using magnesium–aluminum layered double hyd­roxide (LDH). The LDH powders were synthesized by the co-precipitation method. The structural, textural and morphological characterizations were per­formed. To evaluate quickly and effectively the effects of five parameters (initial PC content, contact time, solid/liquid ratio, initial pH and temperature) on the adsorption efficiency, a Hadamard matrix was employed for screening. Sub­sequently, a central composite design was utilized to optimize the adsorp­tion process based on four key parameters. The correlation coefficient for the poly­nomial model was found to be 94 %. Predicted values generated from the res­ponse function matched the experimental data closely, indicating a good agree­ment. Under the selected optimal conditions, a maximum PC removal effi­ciency of 80.85 % was achieved. The reusability of the regenerated LDH by calcination at 500 °C in the adsorption process was assessed over four conse­cutive runs under the selected optimal conditions. The removal percentages of PC and chem­ical oxygen demand indicated that calcined LDH could be a viable alternative for treating OMW.