Fast Degradation and Biodegradability Improvement of Reactive Brilliant Red X-3B by the Cobalt(II)/Bicarbonate/Hydrogen Peroxide System

The cobalt(II)-bicarbonate (HCO 3 – ) complex is a very efficient catalyst for organic dye decolorization with H 2 O 2 as an oxidant, but its mineralization degree is very low. One interesting alternative is the combination of the system with a subsequent biological step. With the aim of employing the Co 2+ -HCO 3 – system as a pretreatment method to dye wastewater, a typical azo dye, reactive brilliant red X-3B (X-3B), was selected as the model compound, and the biodegradability enhancement of the dye was investigated. The results showed that X-3B was effectively degraded by the Co 2+ -HCO 3 – system under various mild conditions, and the BOD 5 /COD ratio of the dye solution could markedly increase from 0.046 to higher than 0.46. The effluent treatment by the system was efficiently post-treated in a batch biological reactor with the COD removal around 44% after 8 h aeration, while a little decrease of the COD value of the raw solution was observed.