“…TiO 2 powders could be employed in solar and UV irradiation systems (photoreactors) because this semiconductor has a high transparency to visible light, high refractive index, and low absorption coefficient. Wide range of metal oxides and sulfides have been used as photocatalysts including ZnO (Daneshvar et al, 2004;Sakthivel et al, 2003;Kormann et al, 1988;Khodj et al, 2001;Gouvêa et al, 2000;Lizama et al, 2002;Kansal et al, 2007;Chakrabarti and Dutta, 2004), WO 3 (Waldner et al, 2007;Sayama et al, 2010;Saepurahmanet et al, 2010;Cao et al, 2011), WS 2 (Jing and Guo, 2007), Fe 2 O 3 (Chen et al, 2001;Bandara et al, 2001;Pal and Sharon, 1998), V 2 O 5 (Akbarzadeh et al, 2010;Teramura et al, 2004a,b), CeO 2 (Lin and Yu, 1998;Coronado et al, 2002;Ji et al, 2009;Song et al, 2007), CdS (Bessekhouad et al, 2004;Reuterġardh and Langphasuk, 1997;Tang and Huang, 1995), ZnS (Torres-Martínez et al, 2001), and CuO (Lim and Kim, 2004;Sathishkumar et al, 2011;Nezamzadeh-Ejheieg and Hushmandrad, 2010). The light intensity in homogeneous and heterogeneous photoreactors determines the LVREA which is proportional to the rate of photochemical reaction.…”