TiO2-pillared saponite and photosensitization using a ruthenium complex for photocatalytic enhancement of the photodegradation of bromophenol blue

In this research, saponite pillarization with TiO2 and photosensitization using a tris(2,2'-bipyridyl)dichlororuthenium(II) complex were reported. The materials were characterized by elemental analysis, X-ray diffraction, gas sorption analysis, Fourier-transform infrared spectroscopy, and diffuse reflectance UV-Visible and scanning electron microscopy. The photocatalytic performance of the materials was studied for the photodegradation of bromophenol blue by considering factors including the light source, pH, and H2O2. The pillarization affected an increasing basal spacing d(001) for the saponite from 14.95 A to 16.27 A and increased the specific surface area from 110 m(2)/g to 154 m(2)/g; meanwhile, the photosensitization did not significantly influence these characteristics. From diffuse reflectance UV-Visible analysis, the band gap energy for the titaniumpillared saponite was found to be 3.24 eV, and a shift in the absorption spectra towards the visible region was identified due to the photosensitization. Study of the photocatalytic activity for bromophenol blue photodegradation implied that increased photocatalytic performance was found for doping of the tris(2,2'-bipyridyl) dichlororuthenium(II) complex into TiO2 either under the UV or visible-light region. The performance was influenced by pH and H2O2, with optimum performance reached at pH = 10 and H2O2 concentration of 5 mmol/L.