Study of Photocatalytic Reduction of Cr（Ⅵ） by Mesoporous Titanium Dioxide Using Lignocellulose as Template

In order to improve the photocatalytic efficiency of titanium dioxide（TiO₂）, mesoporous titanium dioxide（C-TiO₂） was prepared using cellulose nanocrystals（CNC） prepared by sulfuric acid hydrolysis as template by acid hydrolysis and high temperature calcination. The catalysts were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and N₂ adsorption-desorption at low temperature. The results showed that C-TiO₂ particles had no obvious agglomeration phenomenon, uniform particle size distribution, and good pore structure. The average pore size was between 12.03 nm and 23.03 nm, and increased with the increase of roasting temperature. The addition of CNC effectively inhibited the phase transition from anatase to rutile, and the photocatalytic activity of C-TiO₂ was significantly improved. Using K₂Cr₂O₇ as chromium source, the reduction experiment was carried out in the photocatalytic reactor. C-TiO₂ roasted at 600 ℃ showed the highest photocatalytic activity, and the reduction rate of Cr（Ⅵ） reached 99.24% within 1 h.