Abstract

Blue, with view to process design. Terasil Blue is an Antraquinone-type colorant, with the C=O as the colouring group. Experiment were carried out in a photochemical quartz reactor, using a 150 W mercury lamp as a UV source. Microdispersed Terasil Blue solutions, with initial concentration in the range 50-200 (mg/dm3), were treated with hydrogen peroxide (68-3420 (mM)), in the presence of UV light, at 40ºC., for around 40 min. Experiments show that neither H2O2 nor UV light had any effect on Terasil Blue, when these are used on their own. However, joint H2O2/UV treatment effectively decomposes this organic compound, reaching final reductions in colour of up to 98%. Colorant decomposition by H2O2/UV seems to follow three stages. An initial step where hydroxyl ions are formed and UV light is absorbed by ketone groups. This is followed by rapid and steady colorant decomposition until peroxide concentration reaches very low levels. The final stage shows a drastic slowing down of colour reduction, which coincides with the disappearence of hydroxyl ions. The final colour reduction is a function of the initial H2O2 concentration. Even low H2O2 concentrations lead to substantial reductions in colour. However, very high initial peroxide concentrations may not be appropriate since its selfdecomposition is also favoured. Indeed, the rate of H2O2 is a linear function of its initial