engleski

Degradation of Organic Pollutants by Zeolite Assisted AOPs in Aqueous Phase: Heterogeneous Fenton Type Processes

The minimization of water pollution is one of today’ s main areas of scientific activity. The presence of different types of wastewaters containing various organic pollutants has a considerable effect in the environment. Therefore, such wastewaters have to be treated in order to remove or at least to minimize the toxic organic content. Advanced oxidation processes (AOPs), as destructive low- or non-waste generating technologies, represent an alternative when common wastewater treatment technologies are insufficiently effective. Among AOPs, Fenton process offers cost effective source of OH radicals, highly reactive specie, responsible for degradation of organics present in water. However, in some cases relatively high concentration of iron ions in the bulk may demand a secondary treatment. This can be overcome by the usage of heterogeneous Fenton type catalyst, e.g. Fe-exchanged zeolite with iron ions doped in zeolite framework. The overall efficiency of Fenton type processes is also limited by the formation of stable Fe(III)-complexes, which can be overcome by the assistance of UV irradiation. In the framework of this research two heterogeneous Fenton type processes using Fe-exchanged zeolites of ZSM5 and Y type were investigated for the degradation of model pollutant, reactive azo dye C.I. Reactive Blue 137. The experimental work was directed to investigate the efficiency of Fe-exchanged zeolites and to establish their advantages over homogenous Fenton type processes. The influence of UV irradiation on both types of processes, heterogeneous and homogeneous, was also studied. On the basis of decolorization and mineralization degree the overall efficiency of model colored wastewater treatment process was estimated. Homogeneous and heterogeneous Fenton processes yielded with similar decolorization and mineralization, but the concentration of Fe ions in the bulk after the treatment was significantly lower in the later case. Also, usage of heterogeneous catalyst allows process to be operated at milder pH conditions. UV irradiation positively effected on both decolorization and mineralization degree in all applied homogeneous and heterogeneous Fenton type processes.

heterogeneous Fenton; zeolite; wastewater; UV light

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