Enhanced Photodegradation of p-Nitrobenzoic Acid by Binary Mixtures with Ba2+/TiO2 and MCM-41

A novel Ba(II)/TiO2-MCM-41 composite was synthesized using binary mixtures with Ba2+/TiO2 and MCM-41, and Ba2+ as a doping ion of TiO2. The specific surface area and pore structure characterizations confirm that a mesoporous structure with a surface area of 341.2 m(2)/g and a narrow pore size distribution ranging from 2 to 4 nm was achieved using Ba(II)/TiO2-MCM-41. Ba(II)/TiO2 particles were synthesized into 10-15 nm particles and were well dispersed onto MCM-41. The diffraction peaks in the XRD patterns of TiO2-MCM-41 and Ba(II)/TiO2-MCM-41 were all attributed to anatase TiO2. By taking advantage of MCM-41 and Ba2+, the photocatalytic performance of Ba(II)/TiO2-MCM-41 was remarkably enhanced by suppressing its rutile phase, by lowering the band gap energy, and by facilitating the dispersion of TiO2. Therefore, the photodegradation efficiencies of p-nitrobenzoic acid (4 x 10(-4) mol/L) by various photocatalysts (60 min) under UV light irradiation are arranged in the following order: Ba(II)/TiO2-MCM-41 (91.7%) > P25 (86.3%) > TiO2-MCM-41 (80.6%) > Ba(II)/TiO2 (55.7%) > TiO2 (53.9%). The Ba(II)/TiO2-MCM-41 composite was reused for five cycles and maintained a high catalytic activity (73%).