Application of oxidation processes in the purification of wastewaters from phenolic compounds

Abstract

Natural phenolic compounds are significant component of the human diet, as they are present in fruits and vegetables, and they have very important biological activity in the living organisms. Because of their structure, they are subject of numerous oxidation processes, such as autoxidation, but are easily to oxidize in presence of various oxidizing agents and enzymes. Many authors have been investigating phenolic oxidation processes, and have successfully identified their pathways and a significant number of intermediates and products generated by these processes. Also, particular attention has been made to the effects of these processes on food quality and other biological processes in living organisms. Phenols are persistent pollutants of water systems from various agricultural activities and industrial wastewater discharges. It is known that the presence of phenolic compounds in water supplies and industrial effluents directly affects natural processes in the environment due to their toxicity and natural ability to decompose. This property, to easily oxidize and, as a result of it, to mineralize, is practically useful for the treatment of the wastewaters, so it is of global concern to manage the best technology to remove phenols and other organic pollutants, assisted with the oxidation processes. In the aspect of treatment of wastewaters polluted with phenols, we reviewed oxidative processes such as autoxidation, enzyme-catalyzed oxidation, photo-oxidation, electrochemical oxidation and oxidation by Fenton's reagent and, based on the literature data, we presented advantages and disadvantages of these processes compared to each other.