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.