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Application of Hybrid gas/liquid corona reactors and other AOTs for dye removal

Colored wastewaters present a serious problem for environment. Discharge of dyes is undesirable not only for aesthetic reasons(color is visible even in a low dye concentration). Many dyes and their breakdown products are toxic to aquatic life and carcinogenic and mutagenic to humans. Due to these reasons, bleachingand degradation of colored wastewater is still a significant environmental issue. Advanced Oxidation Technologies (AOTs) may be successful method for the wastewater degradation, without any further secondary waste generation. The most important oxidative agent produced in different AOTs is hydroxyl radical that can be used for removing or degradation of organic compounds in water solutions. In previous studies we have compared the efficiency of hybrid corona discharge reactors with AOTs such as Fenton process, Fenton "like" process, ozonation and peroxone process for bleaching and degradation of wastewater containing different concentration of reactive azo dye C.I. Reactive Blue 137 (RB137). Hybrid gas/liquid electrical discharge reactors involve high voltage electrical discharge in water and in the gas phase above the water surface. Two types of Hybrid gas/liquid Corona reactors, known as hybrid series and hybrid parallel corona reactors have been studied. Difference between those types of Hybrid corona reactors relate to the electrodes configuration, which is correlated with amount of produced ozone, hydrogen peroxide and hydroxyl radicals. The impact of solid particles such as zeolites HY and NH4ZSM5 on efficiency of Hybrid corona reactors, Fenton's and Ozone processes was also studied. Decolorization was measured spectrophotometrically in all experiments, while mineralization rate was monitored by the means of TOC parameters in chosen processes. All studied AOTs were showed as effective methods for bleaching of RB137 wastewater solution, especially for the lower dye concentrations. Zeolites NH4+ZSM-5 and H+Y were showed as useful catalysts for dye removal in hybrid corona reactors, especially in parallel setup of hybrid corona reactors. Dye degradation kinetics of peroxone process was monitored. Reactions order as well as rate constant were determined.

AOPs; reactive dye; corona; ozonization; Fenton process; zeolites

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