Synthesis of Hydroxide–TiO2 Compounds with Photocatalytic Activity for Degradation of Phenol

Abstract

Photocatalytic degradation of phenol using titanium dioxide (TiO2), either alone or in combination with other materials, has been tested. Mg/Al hydrotalcites prepared by two methods using inorganic (HC) or organic (HS) chemical reagents, along with mixed oxides produced by calcination of these products (HCC and HSC), were mixed with titanium isopropoxide to obtain hydroxide–TiO2 compounds (HCC–TiO2 and HSC–TiO2) and their photocatalytic activity tested in solutions of 10 mg/L phenol at 120 min under illumination at λUV = 254 nm with power of 4 W or 8 W. The obtained materials were characterized by various techniques, revealing that TiO2 was incorporated into the mixed oxides of the calcined hydrotalcite to form the above-mentioned compounds. The photocatalytic test results indicate that the activity of HCC–TiO2 can be attributed to increased phenol adsorption by hydrotalcite for transfer to the active photocatalytic phase of the impregnated TiO2 particles, while the better results obtained for HSC–TiO2 are due to greater catalyst impregnation on the surface of the calcined hydrotalcite, reducing the screening phenomenon and achieving HSC–TiO2 degradation of up to 21.0% at 8 W. Reuse of both compounds indicated tight combination of HCC or HSC with TiO2, since in four successive separation cycles there was little reduction of activity, being associated primarily with material loss during recovery.