Degradation characteristics of Monoazo and Diazo dye by ozone oxidation

Abstract

The ozone oxidation was chosen to study the degradation characteristics of monoazo (AO7) and diazo (RG19) dyes. The studied was performed in a laboratory scale ozone reactor and conducted with different parameters such as initial dye concentration, contact time and pH. The performance of the dyes removal were evaluated and compared in the aspect of decolourization and mineralization. Colour, chemical oxygen demand (COD), total organic carbon (TOC) and Fourier Transform Infrared (FT-IR) analyses were employed to assist the studied. The results demonstrated that the ozone oxidation was efficient in decolourization and good in mineralization based on the reduction of COD and TOC. The mineralization performance for AO7 is better but the decolourization of RG19 is advantageously. Additionally, an instantaneous drop of pH through the ozone oxidation process indicated the formation of acidic intermediate products. This evidence was supported by the findings of carboxylic acids, sulfite and ketones in FT-IR.