Silver/Platinum Supported on TiO2 P25 Nanocatalysts for Non-photocatalytic and Photocatalytic Denitration of Water
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Denitration of water was investigated by non-photocatalytic and/or photocatalytic processes (UV-A irradiation at 365 nm) using a mixture of Ag/P25 + Pt/P25 monometallic catalysts and Ag–Pt(Pt–Ag)/P25 bimetallic catalysts (2 wt% Ag; 4 wt% Pt) prepared by drop-wise wetness impregnation of TiO2 P25 support. In the bimetallic samples, the influences of the Pt precursor (H2PtCl6·6H2O; K2PtCl6) and of the impregnation order of the metallic salts were examined. The highest N2 yield (42.3%) in the non-photocatalytic process was achieved with the Ag/P25 + Pt/P25 mixture but with ca. 12.6% NO2 − yield. Photocatalytic activity was enhanced in presence of H2 in comparison to H2-free condition. Ag/P25 is the most active photocatalyst, however high NO2 − yield is obtained (32.5%). The bimetallic samples exhibit high versatility, being active both in the non-photocatalytic and the photocatalytic processes. Low NO3 − conversion and high NO2 − selectivity results were obtained from impregnation of Ag first. In contrast, impregnation of Pt precursor from K2PtCl6 first effectively promoted NO3 − reduction towards N2 yield of 36% and particularly low NO2 − yield of 2.7%, due the presence of metallic nanoparticles of different sizes and interaction with TiO2 with a peculiar strong Pt and Ag interaction. Best results obtained in non-photocatalytic and photocatalytic processes are almost similar.
KeywordsNitrate Catalytic reduction Photocatalytic reduction Ag–Pt TiO2
This work was supported by the Spanish Ministry of Economy and Competitiveness (Project CTQ2012-35789-C02-02). A.M.A. acknowledges the financial support to Universitat Rovira i Virgili, École Nationale Supérieure de Chimie de Montpellier, Eurorregión Pirineos Mediterráneo, Aplicacions Medioambientals i Industrials de la Catàlisi, Anton Dafinov and Thomas Cacciaguerra.
- 1.S.I-No.106 (2007) European Communities Drinking Water RegulationsGoogle Scholar
- 4.Mahler RL, Colter A, Hirnyck R (2007) Nitrate and Groundwater. Cis pp 1–4Google Scholar
- 20.Wang G, Xu L, Zhang J, Jin T, Han D (2012) Enhanced photocatalytic activity of TiO2 powders (P25) via calcination treatment. Int J Photoenergy 2012:9Google Scholar
- 33.Zhang F, Miao S, Yang Y, Zhang X, Chen J, Guan N (2008) Size-dependent hydrogenation selectivity of nitrate on Pd–Cu/TiO2 catalysts. J Phys Chem 112:7665–7671Google Scholar
- 37.Viswanathan B, Raj KJA (2009) Effect of surface area, pore volume and particle size of P25 titania on the phase transformation of anatase to rutile. Indian J Chem Sect A 48:1378–1382Google Scholar
- 39.Talat-Mehrabad J, Khosravi M, Modirshahla N, Behnajady MA (2016) Synthesis, characterization, and photocatalytic activity of co-doped Ag–, Mg–TiO2-P25 by photodeposition and impregnation methods. Desalin Water Treat 57:10451–10461Google Scholar
- 41.Sing KSW, Everett DH, Haul RAW, Moscou L, Pierotti RA, Rouquérol J, Siemieniewska T (1985) International union of pure and applied chemistry physical chemistry division reporting physisorption data for gas/soils systems with special reference to the determination of surface area and porosity. Pure Appl Chem 57:603–619CrossRefGoogle Scholar
- 47.Suttiponparnit K, Jiang J, Sahu M, Suvachittanont S, Charinpanitkul T, Biswas P (2011) Role of surface area, primary particle size, and crystal phase on titanium dioxide nanoparticle dispersion properties. Nanoscale Res Lett 6:1–8Google Scholar
- 49.Boitiaux JP, Deves JM, Didillon B, Marcilly CR (1995) Catalytic naphtha reforming: Science and technology. Marcel Dekker, New YorkGoogle Scholar
- 55.Sowmya A, Meenakshi S (2015) Photocatalytic reduction of nitrate over Ag–TiO2 in the presence of oxalic acid. J Water Process Eng 8:e23–e30Google Scholar
- 59.Ohtani B, Iwai K, Nishimoto S, Sato S (1997) Role of platinum deposits on titanium (IV) oxide particles: structural and kinetic analyses of photocatalytic reaction in aqueous alcohol and amino acid solutions. Society 101:3349–3359Google Scholar