Catalytic decomposition of the reactive dye Uniblue A on hematite. Modeling of the reactive surface

Experimental results from the adsorption and subsequent catalytic combustion of the reactive dye Uniblue A on hematite indicate that this iron oxide can he used as an affordable catalyst for environmental purposes. Uniblue A was adsorbed on hematite and the products of the catalytic oxidation in O-2 atmosphere were analyzed by thermal programmed gas-chromatography/mass spectrometry (STDS-GC-MS) analysis. The catalytic combustion of Uniblue A in the presence of hematite led to about 40% conversion of the dye C-content into CO2 at T = 275 degreesC. The activation energy (E-a) for the desorption of CO, and other polyaromatic hydrocarbons (PAHs) from the hematite surface was determined to be 23.4 kcal mol(-1). Identification of the species of Uniblue A in solution and those existing on the hematite surface was earned out in the framework of the generalized two-layer diffuse model. The modeling of the amount of dye absorbed on hematite is in good agreement with the experimental data. (C) 2001 Elsevier Science Ltd. All rights reserved.