The effect of particle size and crystal structure of titanium dioxide nanoparticles on the photocatalytic properties.

Titanium dioxide nanoparticles with different average diameter of particles (8, 18 and 27 nm) and different crystal structure (anatase and rutile) were used for degradation of C.I. Acid Red 88 (AR88) as a model compound. The degree of degradation of AR88 by TiO(2) nanoparticles under irradiation of UV-light (254nm) with TiO(2)-UV100 (8 nm diameter and 100% anatase) is lower than TiO(2)-Merck (27 nm diameter and 95% anatase). TiO(2)-P25 with structure of anatase and rutile (80:20) combination shows higher photoactivity than other samples such as TiO(2)-UV100 and TiO(2)-Merck. Kinetics of removal of AR88 with all of nanosized-TiO(2) particles is pseudo-first-order. The apparent reaction rate constant (k(ap)) for removal of AR88 in the presence of different nanosized-TiO2 particles decreases with increasing of AR88 initial concentration. For TiO(2)-P25 and TiO(2)-UV100 a linear relation and for TiO(2)-Merck a nonlinear relation between k(ap) and light intensity were obtained.