Wet oxidation of high-concentration reactive dyes

Advanced oxidation methods were used to degrade reactive dyes at high Conce ntrations in aqueous solutions. Wet peroxide oxidation (WPO) was found to b e the best method in terms of the removal of: color and total organic carbo n (TOC). Reactive blue (Basilen Brilliant Blue P-3R) was chosen as a model dye for determining the suitable reaction conditions. The variables studied include reaction temperature, H2O2 dos age, solution pH, dye concentration , and catalyst usage. The removal of TOC and color by wet oxidation is very sensitive to the reaction temperature. At 150 degrees C, the' removal of 7 7% TOC and 90% color was obtained in less than 30 min. The initial TOC remo val rate is proportional to the H2O2 dosage. The TOC removal is insignifica nt even when 50% of the stoichiometric amount of H2O2 is used. No color cha nge is observed until the dosage of H2O2 is 100% of the stoichiometric amou nt. The color removal is closely related to TOC removal. When the pH of the solution is adjusted to 3.5, the dye degradation rate increases significan tly. The rates of TOC and color removal. are enhanced by using a Cu2+ catal yst. Another four reactive dyes, Procion Red PX-4B, Cibacron Yellow P-6GS, Cibacron Brown P-6R, and Procion Black PX-BR, were treated at 150 degrees C using WPO. More than 80% TOC was removed from the solution in less than 15 min. The process can remove the colors of all these dyes except Procion Bl ack PX-BR.