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

Abstract

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 TiO₂ nanoparticles under irradiation of UV-light (254nm) with TiO₂-UV100 (8 nm diameter and 100% anatase) is lower than TiO₂-Merck (27 nm diameter and 95% anatase). TiO₂-P25 with structure of anatase and rutile (80:20) combination shows higher photoactivity than other samples such as TiO₂-UV100 and TiO₂-Merck. Kinetics of removal of AR88 with all of nanosized-TiO₂ 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 TiO₂-P25 and TiO₂-UV100 a linear relation and for TiO₂-Merck a nonlinear relation between k_ap and light intensity were obtained.

Keywords:

• Advanced oxidation processes (AOPs)
• heterogeneous photocatalysis
• TiO₂ nanoparticles
• crystalline structure
• nanoparticles size
• decolorization
• C.I. acid red 88

Acknowledgments

The authors thank the Islamic Azad University, Tabriz Branch for financial and other supports.