Semiconductor-assisted photocatalytic degradation of reactive dyes in aqueous solution

This work reports the semiconductor-assisted photochemical degradation of r eactive dyes. In an oxygenated-UV-ZnO system almost total decolorization of Remazol Brilliant Blue R, Remazol Black B, Reactive Blue 221 and Reactive Blue 222 was observed in reaction times of about 60 min. Extending the phot ochemical treatment up to 120 min, mineralization higher than 80% for all t he dyes was observed. During the same period, the residual acute toxicity w as significantly reduced only for Remazol Black B. A systematic optimization study carried out by factorial design showed that for the reactive dyes tested, the ZnO semiconductor exhibits a better effi ciency than that observed with anatase TiO2. A synergistic effect in the co upled TiO2-ZnO system was not observed. (C) 1999 Elsevier Science Ltd. All rights reserved.