Journal of Photochemistry and Photobiology A: Chemistry 148 (2002) 153–159 Photocatalytic decomposition of leather dye Comparative study of TiO 2 supported on alumina and glass beads S. Sakthivel a , M.V. Shankar b , M. Palanichamy b , B. Arabindoo b , V. Murugesan b,∗ a Institut für Solarenergieforschung Hameln/Emmerthal (ISFH), Aussenstelle Hannover, Sokelant str. 5, Hannover 30165, Germany b Department of Chemistry, Anna University, Chennai 600025, India Received 24 July 2001; received in revised form 25 September 2001; accepted 25 September 2001 Abstract TiO 2 supported on alumina and glass beads were prepared and their photocatalytic activities were determined by photo-oxidation of com- mercial leather dye, Acid brown 14 in aqueous solution illuminated with solar light. The progress of photocatalytic degradation of the Acid brown 14 was studied by monitoring the change in the concentration of the dye employing HPLC and measuring the absorbance with UV–Vis spectrophotometer for decolourisation. The photodegradation rate was determined for each experiment and the highest efficiency was ob- served for TiO 2 supported on alumina beads suggesting that the dye molecules are adsorbed on the alumina supports to make high concentra- tion environment around the loaded TiO 2 . The effect of pH on the rate of degradation was followed in the pH range 3–11. Acidic pH range was found to favour the degradation rate. Comparative study of different advanced oxidation methods applied to degrade Acid brown 14 in aque- ous solution was made and solar light/TiO 2 /Fenton system was found to be very effective. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Photodegradation; Acid brown 14; TiO 2 –alumina beads; TiO 2 –glass beads; Fenton reagent; Hydrogen peroxide 1. Introduction In recent years, photocatalytic degradation attracts in- creasing attention as a promising technology for the removal of toxic organic and inorganic contaminants from water and wastewater [1–4]. However, the development of a practical photocatalytic system has not yet been achieved success- fully because many operational parameters are to be consid- ered. The success of photocatalytic degradation process in wastewater treatment will depend on how much energy cost can be brought down. This can be achieved by improving photocatalytic degradation efficiency by catalytic modifica- tion and optimisation of process conditions. The practical limitation in the use of catalyst powder in solar reactor for photodegradation is the separation of the fine catalyst pow- der from the treated wastewater. Thus the development of a viable solar reactor will hinge to a large extent on the degree of success that can be achieved in immobilizing the powder catalyst on a support in such a way as to afford a reason- ably high surface area and accessibility of the immobilised catalyst for photodegradation of the contaminants. Among the various semiconductors employed, anatase phase of TiO 2 is the most preferable material for the photocatalytic ∗ Corresponding author. Fax: +91-44-2200-660. E-mail address: v murugu@hotmail.com (V. Murugesan). process [2,5–7] due to its high photosensitivity, non-toxic nature, large bandgap and stability. The improvement in the photocatalytic behaviour of particulate TiO 2 by intimate incorporation of adsorbent material (alumina) is ascribed to the adsorptive properties of this material. Although TiO 2 has large bandgap (3.2 eV), the main drawback is the charge carrier recombination which occurs within nanoseconds. To circumvent this particular limitation, number of strategies have been proposed to improve the lifetime of charge carriers such as the deposition of metal and coupled semiconductor systems [8–12]. Apart from these, one more approach for the prevention of recombination of the photogenerated elec- tron (e - ) and hole (h + ) is to increase the rate of transfer of electron (e - ) and hole (h + ) to solution species. This can be accomplished by the use of charge transfer medium nearer to the photocatalyst surface. Rapid scavenging of holes can also be promoted by adsorption of the reductant and any oxidised intermediates from the solution by incorporation of more effective adsorption sites. These sites must be nearer to the catalyst active sites so that the hole-generated oxidants (hydroxyl radicals) can reach them before these intermedi- ates are lost through a reaction. This has been accomplished in the presence of strong adsorbents [13]. Unfortunately TiO 2 has low adsorption abilities for organic substances and furthermore target organic substances being in such low con- centrations, the rate of photodecomposition of target organic 1010-6030/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S1010-6030(02)00085-0