Journal ArticleDOI
Simultaneous photocatalytic Cr(VI) reduction and dye oxidation in a TiO2 slurry reactor
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In this paper, the effect of pH and concentration of pollutants on the kinetics of the reactions was evaluated, and the results of a study on the simultaneous Cr(VI) reduction and the Luranzol S Kong dye (from the tannery industry) oxidation by photocatalysis.Abstract:
The semiconductor photocatalytic reduction is a relatively new technique for the removal of dissolved metal ions, such as Cr(VI) and organic compounds in wastewater. Many studies concern only the catalytic activity of TiO 2 with single substrates. However, for practical applications it is necessary to evaluate the photocatalytic simultaneous reduction and oxidation reactions. In this paper, we report the results of a study on the simultaneous Cr(VI) reduction and the Luranzol S Kong dye (from the tannery industry) oxidation by photocatalysis. The experiments were performed in a UV reactor system with a lamp of 150 W, using TiO 2 as a catalyst. We evaluated the effect of pH and concentration of pollutants on the kinetics of the reactions. Isolated tests showed that both Cr(VI) and Luranzol S Kong are degraded in acidic pH, according to the Langmuir–Hinshelwood kinetic model. In neutral pH, the Cr(VI) is not reduced, but this might be explained by the fact that Cr(VI) is not adsorbed on TiO 2 surface. The dye is almost completely degraded by both acidic and neutral pH. Under UV irradiation, photo-induced Cr(VI) reduction is observed in both Cr(VI)–TiO 2 and dye–Cr(VI)–TiO 2 , and dye oxidation is observed in both dye–TiO 2 and dye–Cr(VI)–TiO 2 . The concentration of Cr(VI) and dye, and the pH are the main parameters influencing both reactions. In the simultaneous reduction–oxidation process, the reduction of Cr(VI) proceeds quicker than it does in the single process, showing synergism between the oxidation and reduction reactions.read more
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Journal ArticleDOI
A surface science perspective on TiO2 photocatalysis
TL;DR: The field of surface science provides a unique approach to understand bulk, surface and interfacial phenomena occurring during TiO2 photocatalysis as mentioned in this paper, including photon absorption, charge transport and trapping, electron transfer dynamics, adsorbed state, mechanisms, poisons and promoters, and phase and form.
Journal ArticleDOI
Heterogeneous photocatalytic treatment of organic dyes in air and aqueous media
Krishnan Rajeshwar,Marly E. Osugi,Wilaiwan Chanmanee,C. R. Chenthamarakshan,Maria Valnice Boldrin Zanoni,Puangrat Kajitvichyanukul,R. Krishnan-Ayer +6 more
TL;DR: In this article, a review focusing on the heterogeneous photocatalytic treatment of organic dyes in air and water is presented, which includes historical aspects, dark adsorption of the dye on the semiconductor surface and its role in the subsequent photoreaction, semiconductor preparation details, photoreactor configurations, photooxidation kinetics/mechanisms and comparison with other Advanced Oxidation Processes (e.g., UV/H 2 O 2, ozonation, UV/O 3, Fenton and photo-Fenton reactions), visible light-
Journal ArticleDOI
Treatment of Hazardous Organic and Inorganic Compounds through Aqueous-Phase Photocatalysis: A Review
TL;DR: In this article, the authors focused on the treatment of hazardous wastewater (bearing heavy metals and organic compounds) by photocatalysis and the effects of various parameters such as pH, light intensity, dissolved oxygen, etc.
Journal ArticleDOI
Role of primary active species and TiO2 surface characteristic in UV-illuminated photodegradation of Acid Orange 7
TL;DR: In this paper, the role of primary oxidants in the photodegradation of an azo dye, acid orange 7 (AO7), in UV-illuminated TiO2 suspension was investigated.
Journal ArticleDOI
Highly dispersed palladium nanoparticles anchored on UiO-66(NH2) metal-organic framework as a reusable and dual functional visible-light-driven photocatalyst
TL;DR: This work represents the first example of using the MOFs-based materials as dual functional photocatalyst to remove different categories of pollutants simultaneously, and proves great potential for the design and application of MOFs -based materials.
References
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Journal ArticleDOI
Environmental Applications of Semiconductor Photocatalysis
TL;DR: The slow pace of hazardous waste remediation at military installations around the world is causing a serious delay in conversion of many of these facilities to civilian uses as discussed by the authors, which is a serious problem.
Journal ArticleDOI
Heterogeneous photocatalysis: Transition metal ions in photocatalytic systems
TL;DR: In this paper, the presence of transition metal ions in photocatalytic reactions is reviewed according to two main approaches: (a) the influence of metal ions on the rate of photocatalysis and (b) the transformation of the ions to less toxic species or their deposition on the semiconductor catalyst surface for recovery of expensive and useful metals.
Journal ArticleDOI
Photocatalytic reduction of Cr(VI) in aqueous solutions by UV irradiation with the presence of titanium dioxide.
Young Ku,In-Liang Jung +1 more
TL;DR: The reduction of Cr(VI) in aqueous solution by UV/TiO2 reduction process was studied under various solution pH values, TiO2 dosages, light intensities, dissolved oxygen levels and other operating conditions to determine the reduction rates by photocatalytic-induced elections.
Journal ArticleDOI
TiO2-assisted photodegradation of dye pollutants : II. Adsorption and degradation kinetics of eosin in TiO2 dispersions under visible light irradiation
TL;DR: In this paper, the degradation kinetics followed a Langmuir-Hinshelwood type equation and the rate was greater in acid media than in neutral and alkaline media, which correlates with the adsorption behavior of eosin on the TiO2 surface.
Journal ArticleDOI
Removal of toxic metal ions from wastewater by semiconductor photocatalysis
Dingwang Chen,Ajay K. Ray +1 more
TL;DR: In this paper, physical adsorption and photocatalytic reduction of eight environmentally significant metal ions in TiO2 suspensions of Degussa P25 and Hombikat UV100 were investigated.
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