Synthèse des poudres ultrafines de TiO[indice inférieur 2] par plasma inductif

Abstract

The gas phase synthesis of nanosized titania powders was experimentally investigated by oxidation of titanium tetrachloride in an induction plasma reactor.The product titania particle size as well as their phase composition were controlled mainly by the relative amounts of oxygen to TiCl[indice inférieur 4] in the flame, the nature and the rate of the quenching gas. Spherical particle morphology was predominant in the powders produced with a mean particle diameter in the range of 10 to 100 nm. The rote of silica as dopant in the formation of ultra-fine titania was also studied in the induction plasma reactor. Titania was produced by the vapour phase oxidation of TiCl[indice inférieur 4] in the presence of dopant silicon tetrachloride vapour.The presence of silica decreased the particle sizes of the produced powders and increased their specific surface area. Differential thermal analysis (DTA) showed retardation in the phase transformation from anatase to rutile in the presence of silica doping of the powder.The effects of different amount of silica dopants on titania phase composition and particle size are presented. An evaluation of the photocatalytic activity of powders produced was evaluated for the destruction of phenol in water. This application is important in wastewater treatment.The results of the tests are compared with commercially available ultra-fine titania powders, Degussa P25.The powders obtained with a higher TiCl[indice inférieur 4] flow rate showed higher photoactiviy than those produced at lower TiCl[indice inférieur 4] flow rates, for the same plate power.