%0 Journal Article
%T Mineralization of Azo Dye Using Combined Photo-Fenton and Photocatalytic Processes under Visible Light
%A Selma K. Kuriechen
%A Sepperumal Murugesan
%A Samuel Paul Raj
%J Journal of Catalysts
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/104019
%X Visible-light-assisted photodegradation of an azo dye, Reactive Red 180 (RR180), in the presence of nitrogen-doped TiO2 (N-TiO2) has been studied. The photodegradation of RR180 is evaluated through decolorization studies and total organic carbon analysis. The efficacy of hydrogen peroxide (H2O2), potassium peroxomonosulfate (oxone or PMS), and potassium peroxodisulfate (PDS) in improving the photodegradation of the dye in the N-TiO2-RR180 system is also examined. The effect of combining photo-Fenton-like reaction with N-TiO2-mediated photodegradation of RR180 under visible light has been investigated. The photoactivity of N-TiO2-RR180-Fe3+/Cu2+-oxidant systems is compared with the individual techniques of photocatalysis and photo-Fenton-like reactions. The coupled system possesses superior photomineralization ability towards the abatement of RR180. 1. Introduction Now a days, combining several oxidation systems for the degradation and mineralization of organic pollutants has become a common practice, for the reason that a single process usually cannot reach a desirable effectiveness in the degradation and mineralization of organic pollutants. Heterogeneous photocatalysis using titania photocatalyst has been established as a principal advanced oxidation process (AOP) for wastewater treatment. For a century, photo-Fenton reactions were also considered widely for the removal of organic pollutants [1¨C7]. The combination of heterogeneous photocatalysis with another AOP can be cost-effective as long as this combination produces a synergic effect. In the earlier efforts to increase the photodegradation efficiency through combined systems, photocatalysis coupled with ultrasonic treatment [8], integrating photocatalysis with membrane filtration [9], or combinations of photo-electro-Fenton [10], sono-Fenton [11], and electro-Fenton [12] processes were carried out, and better performances were observed. Not many attempts were made in pairing photocatalysis and photo-Fenton-like reactions for wastewater treatment. In general, the rate of photodegradation of pollutants is proportional to the efficiency of reactive radical formation. In photocatalysis- and photo-Fenton-coupled systems, two independent sources of hydroxyl radicals exist: (a) occurrence of hydroxyl radicals in photocatalytic reactions on titanium dioxide and (b) Fe(III) aqua complexes are independent and are more efficient sources of hydroxyl radicals through the photoredox reaction [13]. But the efficiency of photocatalytic process is limited by the recombination of photogenerated electrons and holes
%U http://www.hindawi.com/journals/jcat/2013/104019/