ABSTRACT
The photoactivated periodate (UV/IO4 −) system is one of the recent advanced oxidation processes (AOPs) that has been applied to degrade various persistent organic pollutants in aqueous liquids. Periodate photolysis (λ <300 nm) produces a number of reactive species such as OH, IO3, IO4, O(3P), and O3 that are capable of degrading persistent chemicals and recalcitrant pollutants in the environment.
This chapter assesses the applicability of the UV/IO4 −-advanced oxidation process for the degradation of one persisting organic pollutant, chlorazol black (CB), in several water matrices (deionized water, mineral water, and secondary effluents of wastewater treatment plants). CB is a persistent azo dye that is not only refractory to biodegradation but also toxic and mutagenic. Firstly, an overview of the chemistry and the previous applications of the UV/IO4 − process is given. Then, the generation of reactive species during CB degradation by the UV/IO4 − system is been proven in different matrices using the radical probe technique. The main radicals implicated in the degradation process are clarified through simulation results. Lastly, the impact of various operational conditions, such as reactant loadings, solution pH, and temperature, on the degradation of CB has been clarified for the different water systems. The process has shown a pH limitation in real water matrices. In addition, the secondary effluents of wastewater treatment plants significantly reduced the degradation process due to the presence of natural organic matter. The results obtained also indicate that periodate photoactivation is a powerful tool for the treatment of organic pollutants in natural mineral water.
