Degradation of phenolic wastewaters by solar/TiO2 and solar/TiO2,/H2O2 processes

The application of Advanced Oxidation Processes (AOPs) (solar/TiO 2 and solar/TiO2/H2O2) to treat phenol, o-cresol, m-cresol, and p-cresol wastewaters was investigated. The experiments were performed in batch solar reactor using TiO2 as catalyst. The effect of the hydrogen peroxide concentration on the degradation kinetics was evaluated in the range of 0.15-1.5 g/L. It was observed that the degradation rate increased as the hydrogen peroxide increased, but excessive H2O2 concentration was detrimental. The rate of degradation is two to three times faster in solar/TiO2/H 2O2 process when compared with solar/TiO2 process. In the presence of inorganic salts, the phenol removal was 19% and 90% in solar/TiO2 and solar/TiO2/H2O2 process, respectively. For untreated samples of 100 mg/L the BOD/COD ratio is 0, while solar photocatalytic treatment of 1 h permits its enhancement up to values near 0.66 and 0.57 for m-cresol and o-cresol; for phenol and p-cresol the values were nearer to 0.53 and 0.65 after 2 h and 3 h phototreatment respectively, which represent considerable biodegradability of wastewaters. Copyright © 2012 Inderscience Enterprises Ltd.