Photocatalytic degradation of azophloxine on porous La2Ti2O7 prepared by sol-gel method

Abstract

Cetyltrimethyl ammonium bromide (CTAB) was used in a sol-gel route to synthesize porous lanthanum titanate. The materials are composed of perovskite La2Ti2O7 in monoclinic system. The addition of CTAB does not cause phase transformation, but leads to a slight decreasing tendency of La2Ti2O7 crystallite size. Both the pore volume and pore size distribution range are enlarged after using CTAB. The sample obtained with 4 g CTAB has the maximum BET specific surface area of 42.4 m2/g. When the amount of CTAB is less than 4 g, the increase in photocatalytic degradation efficiency is almost in linear relationship to the amount of CTAB. The reaction rate constants are 0.0032, 0.0116 and 0.0237 min−1 on the La2Ti2O7 samples obtained using 0, 2 and 4 g CTAB. The functional groups in azophloxine molecule are decomposed during photocatalytic oxidation with extending irradiation time.