High Efficiency Photocatalytic Mineralization of C.I. Reactive Red 2 using Transparent Self-Assembled Nanopin-Like Titania with High Preferential (101) Orientation on Alumina Thin Film in Aqueous Environments

Abstract

This investigation elucidated the mineralization of an environmental pollutant; C.I. Reactive Red 2 (RR2) using transparent self-assembled nanopin-like titania with high preferential (101) orientation on alumina thin film (Ti@Al-nanopin-f) in water and UV/TiO2 system. Mineralization efficiency of the azo dye by Ti@Al-nanopin-f thin film is compared with a thick film of Degussa P25 titania photocatalyst (P25-f) and a dense thin film of titania on a glass substrate (Ti-f). The results shown high efficiency of fully mineralization of RR2 by titania nanopin thin film. The decolorization reactions obeyed the pseudo-first-order kinetics in all tested systems. The photodegradation rates of chemical compounds on semiconductor surfaces follow the Langmuire-Hinshelwood model. At pH 7, the mineralization rates followed the order Ti@Al-nanopin-f (k = 0.066 min−1 and t1/2 = 10.5 min) > P25-f (k = 0.0125 min−1 and t1/2 = 55.4 min) > Ti-f (k = 0.0042 min−1 and t1/2 = 165.0 min). High preferential (101) orientation of the anatase particles on alumina substrate not only markedly increase the surface area but also prepare a suitable sites for electron and hole injection to species of solution.