Treatment of Sulfonated Azo Dye Reactive Red 198 by UV/H₂O₂

Abstract

UV/H 2 O 2 system was tested on the color removal of sulfonated azo dye Reactive Red 198 (RR), which is widely used in textile process. The effects of hydrogen peroxide concentration, temperature, pH, and the in-line addition of hydrogen peroxide on high color and chemical oxygen demand (COD) removals were investigated. The kinetic of dye decolorization was also determined. The results showed that 2% H 2 O 2 decreased the process efficiency, while 1% H 2 O 2 solution led to a better performance of the system. Despite the fact that the pH increase had small effect on color removal, it affects positively COD removals. The same behavior was found for temperature increase. A high temperature resulted in a slight decrease in color removal and a sharp decrease for COD removal. In addition the H 2 O 2 in-line provided a small improvement in both color and COD removals. UV/1% H 2 O 2 treatment was the most efficient, the good performance was linked to higher amount of hydroxyl radicals formed.