International Journal of Chemistry; Vol. 7, No. 2; 2015 ISSN 1916-9698 E-ISSN 1916-9701 Published by Canadian Center of Science and Education 39 Study Self-cleaning of Congo Red from Cotton Fabric Loaded by Zno-Ag Amjed M. Oda 1 , Hameed H. Ali 2 , Abbas J. Lafta 3 , Hussein A. Esmael 3 , Ali A. Jameel 1 , Abbas M. Mohammed 1 , Inas J. Mubarak 3 1 University of Babylon, College of Basic Education, Iraq 2 Kufa University, College of Science, Iraq 3 University of Babylon, College of Science, Iraq Correspondence: Abbas J. Lafta, University of Babylon, College of Science, Iraq. E-mail: abbaslafta2009@yahoo.com Received: March 30, 2015 Accepted: April 30, 2015 Online Published: July 6, 2015 doi:10.5539/ijc.v7n2p39 URL: http://dx.doi.org/10.5539/ijc.v7n2p39 Abstract The current work involves modification of zinc oxide by doping silver, this was achieved by photodeposition method. Modified zinc oxide was investigated using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Both of ZnO and Ag doped ZnO was fabricated on a cotton texture. The photocatalytic activity of these materials was investigated by following the decolorization of congo red from simulated industrial wastewater. The decolorization of congo red over fabricated-ZnO-Ag was more efficient in comparison with non- fabricated catalysts. Different reaction parameters were undertaken including the effect of pH of the solution, irradiation time and the effect of light intensity. Complete dye removal over fabricated materials took three hours while it took 4.5 for non-fabricated materials. Keywords: Zinc oxide, congo red dye removal, fabricated zinc oxide 1. Introduction Photocatalytic reactions were emerged more than forty years ago when Fujishima and Honda reported photocatalytic splitting of water on titanium dioxide electrode (Manoj , Shaji and Santhosh, 2012). This type of reactions is based on the photoexcitation of the particles of the phtocatalyst with light of energy that is equal to greater than its bandgap (Eg) (Hind, Baha, Hussein, Ahmed, and Saba, 2013). This process produces valence band holes (h + VB ) as well as conduction band electron (e - CB ) (Narendra, Oza, and Ingale, 2014). The positive holes normally diffuse to the surface and act as a trap for hydroxyl groups, while conduction band electrons interact with adsorbed oxygen on the surface of the photocatalyst( Rizzo, Meric, Guida, Kassina, and Belgiorno, 2009). Generally, the first step in the heterogeneous photocatalytic reactions for the organic and inorganic compounds is the producing excited state of photocatlyst upon absorbing a light with a proper energy (Agustin, and Gonzalez, 1988). The second step is the de-excitation of the photocatalyst via diffusion of charge carriers into the surface and then reacting with the pre-adsorbed species on the surface (Alan, and Desmond, 11991) . In case of absence of redox species on the surface, these e- CB and h + VB are recombined together in a recombination process ( Ghaed, Hossaini, and Ramezanis, 2012) (Gunnar, Niklasson, and Claes, 2007). However, presence of oxygen is very essential to perform this type of reactions as it act as trap for conduction band electron under this circumstances oxygen works as an oxidant and generate some of reactive radical species such as O 2 .- O - , and O 3 - on the surface (Gopel, Rocker, and Feierabend, 1983). These active radicals contribute in the initiation of photocatalytic reactions that are proceeded on the surface (Henglein, 1982). The activity of the photocatalytic reactions can be enhanced by addition of some inorganic species such as H 2 S 2 and H 2 O 2 (Malinda, Reichert, Chia, and Javier, 2014). Generally, backelectron transfer can reduce the activity of the photocatalyst so the main challenge in this context is how to reduce the rate of recombination reaction which leads consequently to improve the activity of the photocatalyst. This aim can be conducted by surface modification. This can be done by some methods such as metal deposition, coupled of semiconductors, and surface sensitization, and metal and non-metal deposition(Noriyuki, Osamu, and Youkoh, 1995). Metal deposition can lead to improve the photocatalytic activity of the photocatalyst by altering some of chemical and