The Effect Of InVO4 Coupling On The Photocatalytic Activity Of Anatase and Mixed Phase TiO2 For Organic Decomposition

To increase sustainability of water systems, focus must be turned to the removal of persistent contaminants, including dyes, pesticides, and cyanobacterial metabolites. Photocatalysis, an Advanced Oxidation Process, has greater potential for treating persistent organic contaminants than traditional methods such as chlorine and potassium permanganate. TiO₂ is an effective, inexpensive, and stable photocatalyst used for the decomposition of organics, however; it is limited by its band gap (3.0-3.2 eV) which primarily absorbs in the ultraviolet portion of the spectrum.  This project is innovative because it will use the indium vanadate semiconductor, InVO₄, alloyed to TiO₂, to increase visible range photoactivity.  TiO₂ occurs in several crystalline phases (e.g. anatase, rutile, and brookite).The objective of this study was to determine if the effect on photoactivity of InVO₄ alloying was consistent for pure phase and mixed phase TiO₂.  Pure anatase and mixed phase TiO_2­ (Degussa P25) were used. Batch reactions were carried out at atmospheric pressure and ambient temperature in 1-L pyrex reactors stirred at 250 rpm. The light source was “Daylight Spectrum” florescent bulbs. Photocatalytic activity was determined by monitoring methyl orange concentration using UV-Vis analysis at 15 min intervals. From the data collected, the effect of InVO₄ coupling on the photoactivity was not consistent between anatase and P25 TiO_2­. Decomposition by the anatase composite was retarded, but decomposition by the mixed phase composite was enhanced.  Although these results were unexpected, current research implicates decomposition may occur via two different mechanisms, which may explain why the coupling of InVO₄ affected the phases differently.