The commercial azo dye C.I. Reactive Orange 4 in its reactive and hydrolysed forms can be efficiently photodegraded, using commercial samples of TiO 2 as a photocatalyst. With UV light, aqueous solutions containing only dye and no dyebath additives are decolorised slightly more rapidly with Riedel-de-Häen TiO 2 than with Degussa P-25 TiO 2. The rate of decolorisation increases markedly with increasing pH. Sunlight is also very effective as a light source. On the other hand, comparison experiments involving UV irradiation of hydrolysed and unhydrolysed Reactive Orange 4 in a simulated spent dyebath showed Degussa P-25 TiO 2 to be significantly the more efficient catalyst, giving more than 90% decolorisation after 20 minutes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.