Carbon aerogel materials promoted catalytic ozonation of residual dyes in waste effluents from cotton dyeing

Abstract

Reactive dyeing of cotton generates large volume of wastewater containing residue dye contaminants. In order to reduce adverse impacts to the environment, the waste effluents must be reclaimed through appropriate processes before charging to the natural water bodies. In this study, carbon aerogel materials, including pure carbon aerogel and its supported metal oxides, was reported in catalytic ozonation of residue dyes in wastewater. The commercially available reactive dye, namely C.I Reactive Blue 19, was used as the probe contaminant. Dye degradation in catalytic ozonation processes was estimated in terms of color and COD removal. The results demonstrated that the catalysts rarely involved in color removal, but displayed promising potentials in facilitating COD removal in dyeing effluents, in which COD removal was significantly promoted comparing to ozonation alone without catalysts. In the specific conditions, especially for the supported metal oxides, COD removal could attain 80% after 3 h treatment, whereas it was only 45% in ozonation alone. In addition, effects of conditional parameters on catalytic ozonation efficiency as well as the reusability of catalysts were also investigated. The results suggested that the catalyst materials exerted outstanding catalytic stability during repeated use, and increasing catalyst dosage, ozone concentration and pH would promote dye degradation especially for COD removal.