Alumina coating with TiO2and its effect on catalytic photodegradation of phenol andp-cresol

Abstract

BACKGROUND This study is focused on the peptization of Boehmite and titanium alkoxide (modified sol–gel method) to obtain Al2O3–TiO2 mixed oxides taking advantage of the physicochemical properties of TiO2 and Al2O3. TiO2 is an important semiconductor and the most active photocatalyst. Al2O3 is an insulator with high surface area and thermal, chemical and mechanical resistance. It is possible to produce high surface area materials, where TiO2 is dispersed on the alumina surface for photodegradation of pollutants. RESULTS γ-Al2O3–TiO2 (5, 10 and 15 wt% TiO2) mixed oxides presented stabilization of the anatase phase. Rietveld studies showed incorporation of the Al3+ into the TiO2 anatase and Ti4+ into the Al2O3. They exhibit higher specific surface area than pure TiO2. The TiO2-coated alumina surface with small TiO2 particles produced a large number of active sites on the surface. The sample with 15 wt% of TiO2 presented the highest photodegradation of p-cresol and phenol. CONCLUSION The addition of TiO2 to the alumina improved the photoactivity of pure TiO2 producing materials with higher surface area covered with TiO2. Alumina delayed the recombination of photogenerated electron–hole pairs favoring the formation of highly reactive •OH radicals. The photodegradation of p-cresol and phenols increased with TiO2 loading increase. © 2016 Society of Chemical Industry