Catalytic wet peroxide photo-oxidation of phenolic olive oil mill wastewater contaminants: Part I. Reactivity of tyrosol over (Al–Fe)PILC

The catalytic photo-oxidation of tyrosol, a representative compound of the polyphenolic fraction typically found in olive processing wastewaters, has been investigated using Al–Fe pillared clay. The montmorillonite was pillared by mixed Al–Fe complexes, its properties being determined by DRX, BET surface area and chemical analysis techniques. The tests were performed on a laboratory scale set-up.Important factors affecting catalyst activity and tyrosol removal efficiencies were studied, mainly, the concentrations of the catalyst, tyrosol pollutant and H2O2 oxidant. The effect of pH and temperature was also investigated. A pseudo-first-order kinetics with respect to the tyrosol concentration was found to hold. The experimental results indicate that under mild conditions and oxidant contents lower than stoichiometric (28%), the use of (Al–Fe) pillared montmorillonite allows a significant TOC abatement and a total elimination of tyrosol, without significant leaching of Fe ions. The toxic potential of tyrosol degradation was investigated with the bioluminescence test using the LUMIStox and the results were expressed as relative toxicity index.