Influence of Textile Dyes Structure on Photooxidative Decolorization Rate and Electricity Consumption in UV/H2O2 Process

Many advanced oxidation processes have been proposed for the treatment of synthetic organic dyes (photocatalysis, UV/H2O2, Fenton, etc). These processes are tested on individual dyes and it is actually difficult to find clear relations between the results obtained by different teams. Furthermore the chemical nature of the tested dyes is often unknown. In order to understand the relations between the chemical structure of the dyes and the efficiency of the oxidation process, photooxidative decolorization of four textile dyestuffs, C.I. Acid Orange 7 (AO7), C.I. Acid Orange 8 (AO8), C.I. Acid Orange 52 (AO52) and C.I. Acid Blue 74 (AB74), was investigated by UV/H2O2 in a laboratory scale continuous column circulation photoreactor. Decolorization of the dyes was found to follow pseudo-first-order kinetics, and hence the figure-of-merit electrical energy per order (EEo) is appropriate for estimating the electrical energy efficiency. The EEo values were found to depend on the concentration of H2O2, concentration and basic structure of the dye. This study showed that these textile dyes could be treated easily and effectively with the UV/H2O2 process with EEo values between 0.4 and 5 kWh m-3 order-1, depending on their chemical structure, initial concentrations of dyes and H2O2.

Keywords:

Advanced Oxidation Processes , Electricity consumption , Molecular Structure , Textile Dye , UV/H2O2