Degradation characteristics of monoazo and diazo dye by using ozone oxidation

Abstract

The degradation characteristics of monoazo Acid Orange 7 (AO7) and diazo Reactive Green 19 (RG19) were investigated using ozone oxidation. It was evaluated based on colour, chemical oxygen demand (COD) and total organic carbon (TOC) removal. The effect of operational parameters such as initial dye concentration, contact time and pH were also being 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 Fourier Transform Infrared Spectroscopy (FT-IR).