11 th European Congress on Catalysis – EuropaCat-XI, Lyon, France, September 1 st -6 th , 2013 Discoloration of azoïc Thiazol Yellow dye by gliding arc plasma process in the presence of TiO 2 catalyst A. Tiya Djowe 1, 2 , E. Acayanka 1 , A. P. Mbouopda 1 , S. Laminsi 1 , E. M. Gaigneaux *2 1 Inorganic Chemistry Department, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon 2 Institute of Condensed Matter and Nanosciences (IMCN), Division “MOlecules, Solids and reactiviTy” (MOST), Université catholique de Louvain, Croix du Sud 2/L7.05.17, 1348 Louvain-la-Neuve, Belgium (*) corresponding author: eric.gaigneaux@uclouvain.be antoine.tiyadjowe@uclouvain.be Keywords: Gliding arc plasma, coloured wastewater, discoloration, Thiazol Yellow, Photocatalyst, TiO 2 1 Introduction Nowadays, many industries produce enormous quantities of highly coloured wastewaters, which are often tox- ic and resistant to conventional treatment techniques. The use of synthetic dyes in the textile and food industry con- stitutes serious threats to public health. The most common types of these dyes are the azoïc and/or anthraquinonic ones, which are suspected carcinogens [1, 2]. Discoloration of dye-containing effluents is therefore necessary and has received increasing attention during the last decade. In this work, we have used a gliding arc plasma (GAP) process in combination with Degussa P25 titanium di- oxide (TiO 2 ) as photo-catalyst to treat a synthetic wastewater containing the azoïc Thiazol Yellow dye (TY). The interaction between the non-thermal plasma and the aqueous medium leads to the formation of active species that induce acidifiying and oxidizing effects in the target solution. These species are considered to be NO• and HO• radicals formed as a result of electron (or/and photon) impact dissociation of water and nitrogen molecules present in the feeding gas [3]. Furthermore, GAP is also a source of UV radiation [4] which can enable the excitation of the TiO 2 surface and thus generate active dissociated electron hole pairs. The combination of plasma and TiO 2 can be therefore used for colour abatement of wastewaters containing organic dyes. 2 Experimental Discoloration experiments were carried out in a GAP batch reactor. For a given exposure time t*(min), 450mL of a Thiazol Yellow solution of various concentrations (25, 50, and 100mg.L -1 ) was disposed normally to the axis of the water cooled glass reactor at a distance of about 50 mm from the electrode tips. The solution was magnetically stirred. The selected feed gas was water saturated air (humid air), provided by a compressor and passing through a bubbling flask containing dionized water at room temperature before entering the reactor (gas flow rate optimized at 800 L.h -1 ). The initial pH of the solution was adjusted to the appropriate value (pH=3.0, 5.5, or 9.0) using 1.0 M H 2 SO 4 or 1.0 M NaOH. Solutions were exposed to plasma for differ- ent times t* = 10, 20, 40, 60min. After the discharge was switched off, an aliquot of the exposed solution was immediately ana- lyzed (UV-Vis, pH and conductivity measurements). The concentration of dye after each exposure time was measured using a double beam UV-Vis spectrophotometer at 402 nm wavelength. Figure 1 shows the scheme of experimental setup. Fig. 1. Scheme of the experimental setup