ORIENTAL JOURNAL OF CHEMISTRY www.orientjchem.org An International Open Free Access, Peer Reviewed Research Journal ISSN: 0970-020 X CODEN: OJCHEG 2018, Vol. 34, No.(2): Pg. 1000-1010 This is an Open Access article licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License (https://creativecommons.org/licenses/by-nc-sa/4.0/ ), which permits unrestricted NonCommercial use, distribution and reproduction in any medium, provided the original work is properly cited. Titanium dioxide as a Catalyst for Photodegradation of Various Concentrations of Methyl Orange and Methyl Red dyes using Hg Vapour Lamp with Constant pH A. KISTAN 1,2 *, V. KANCHANA 3 , L. SAKAYASHEELA 2 , J. SUMATHI 2 , A.PREMKUMAR 2 , A.SELVAM 2 and THAMINUM ANSARI A 4 1 Research and Development Centre, Bharathiar University at Coimbatore, India. 2 Panimalar Institute of Technology, Chennai-123, India. 3 Sree Sastha Institute of Engineering & Technology, Chennai, India. 4 P.G. Research Department Muthurangam Government Arts College, Vellore, India. *Corresponding author E-mail: vishmikrish@gmail.com http://dx.doi.org/10.13005/ojc/340250 (Received: January 01, 2017; Accepted: February 10, 2018) ABSTRACT The photo-catalytic activity of TiO 2 catalyst is very much useful to removal of color from dye industry effluent from tanneries, textile industry, and Ink factory. The Novelty of this study, we have found on a very simple method to compare the photocatalytic activity of titanium dioxide for the different concentration of two different Organic dyes (Methyl Orange and Methyl Red) which were not compared in the past studies. This method can be carried out in a normal chemical laboratory. and easy way with limited use of chemicals and simple lab equipment’s. Dye solutions having pigments with high photocatalytic activity lose their color within several minutes of UV-Visible radiation exposure (optical windows 160W (Hg lamp medium pressure)) whereas, dye solutions having UV-stable TiO 2 would not degrade within several hours of radiation exposure. For both dyes the color started fading quickly when the light radiation was passed continuously for a long time (15 to 120 minutes).It was also found that concentration of both dyes decreased, with time or the degradation increased. The effect of varying the dye concentration increases with degradation rate decreases. The rate constant value undergoes a marginal decreases at pH = 4.2 when the Methyl Orange dye concentration was increased. The degradation measurements were carried out using Shimadzu UV-Visible 1601 spectrometer in the photon energy range of wave length 200 to 700 nm aid of glass cell (made of Quartz) with 10mm optical path length. Keywords: Organic dyes, Hg lamp, pH, Methyl Orange (MO), Methyl Red (MR), Degradation.