The preparation of vanadium-doped TiO2-montmorillonite nanocomposites and the photodegradation of sulforhodamine B under visible light irradiation

The photodegradation of sulforhodamine B on vanadium-doped TiO₂-montmorillonite (TiO₂-MMT) nanocomposites was investigated under visible light irradiation. V-TiO₂-MMT nanocomposites with different amounts of MMT were prepared by a sol-gel process. The microstructure and properties of V-TiO₂-MMT were characterized by XRD, TEM, XPS, DRS, nitrogen adsorption isotherms, and FTIR. These analytic results indicated that the different Ti/MMT ratios exerted a great influence on their microstructures and their photocatalytic activities. The average sizes of V-TiO₂-MMT were smaller than those of pure TiO₂ and V-TiO₂. And the layered structure of MMT was completely destroyed in the V-TiO₂-MMT with the relatively high ratio of Ti/MMT (240, 120, 80, 60 mmol/g), but it retained the partial MMT layered structure and had an enlargement of some basal space of MMT in V-TiO₂-MMT with the relatively low ratio of Ti/MMT (30, 24 mmol/g). V-TiO₂-MMT/120 (120 denotes the ratio of Ti/MMT is 120 mmol/g. The names of other catalysts followed the same convention.) and V-TiO₂-MMT/30 had relatively higher photocatalytic activity in comparison to the others. Besides, in the preparation process, we selected V-TiO₂-MMT/120 using different washing media to examine the effect of washing medium on the photocatalytic activity. The result indicated that it was critical to choose a proper washing medium to obtain an optimal photocatalytic activity.