Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PP-IV-31PHOTOCATALYTICAL ACTIVITY OF HEAT-RESISTANTTITANIUM DIOXIDE ALLOYED WITH ANION IMPURITIESSedneva T.A., Lokshin E.P., Kalinnikov V.T.Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials RAS(Kola Science Centre), Apatity, Murmansk Regione-mail: sedneva@chemy.kolasc.net.ruIt is known that photocatalytical systems on the basis of TiO 2 are capable, when exposedto UV radiation, of providing an environmentally friendly, reagentless decomposition oforganic and bacterial contamination of air in flow-type reactors. For effluent purification,especially in regions with fairly intense daylight illumination, more promising areaccumulation tanks with periodically regenerated photocatalyst [1-3].The conventional photocatalyst applied worldwide is TiO 2 of P25 brand produced byDegussa. As is current practice, the electric conductivity and, consequently, photocatalyticactivity (PCA), are increased by alloying TiO 2 with donor substitutional impurities. In P25,this impurity is OH – whose content, proceeding from loss on ignition, corresponds to aconcentration of about 7.8·10 20 cm –3 , which exceeds conventional concentrations by an orderof magnitude. However, in P25 they are distributed unevenly since it contains 10-20% ofrutile. It can be surmised that the rutile PCA is not maximally possible.The work aims at creating effective and thermally stable photocatalysts on the basis ofnano-size powders alloyed with TiO 2 anion impurities.The samples were obtained by low-temperature hydrolysis of titanium salts in ammoniawater containing weighed amounts of F – or PO 3– 4 anions. Thermal treatment was carried outat 60-1150 °C. The resulting samples were characterized relatively unalloyed ones (Cl) byBET, XPA and SEM microscopy. Their PCA was assessed by the level of degradation ofbrightly-red ferroine (FEK-56 PM) reduced in daylight.The even distribution of alloying ions in the resulting anatase (XPA) in quantities of1÷7·10 20 аt·сm –3 sustains a developed surface (250-50 m 2·g –1 ) of the alloyed samples up to thecalcination temperature of 700-900 °C.The PCA of alloyed TiO 2 increases in the impurity series Cl – 3–, PO 4 and F - , beingcomplexly affected both by impurity content and treatment temperature. As shown by SEM,the decisive effect on the forming morphology is that of the nature of the anion. The F-surfaceof the samples is homomorphous and highly dispersive up to the temperature of rutilization.In the region of 400-500 °C the PCA diminishes probably due to restructuring of fluorinatedanatase (according to XPA). The PCA of F – 3–and PO 4 modified TiO 2 did not change in the450