hplc-ms/ms mechanistic study of direct yellow 12 dye degradation using ultraviolet assisted ozone process

Hplc-ms/ms degradation mechanism of direct yellow 12 (dy-12) dye using o3 associated with uv was studied. the influent of different conditions such as ph, initial dy-12 dye concentration and reaction time were studied in a batch reactor method. the results revealed that the ph value and dy-12 initial concentration controlled the removal process. the maximum color removal was achieved in alkaline condition (ph 9) as compared to neutral or acidic conditions. the color removal of dy-12 dye followed the first-order kinetics. when uv was applied with ozone simultaneously, the first order rate constant (kd) increased, and the time of dye decolorization shortened to 10 min for 200 ppm dye concentration. these results indicated that the application of uv can reduce the reaction time and dose of ozone. gas chromatography-mass spectrum and hplc-ms/ms analyses of the treated synthetic dye solution at the end of the treatment time showed no toxic organic compounds were detected. the cod decreased by more than 85% of the initial cod of the untreated dy-12 dye concentration.