用木质纳米纤维素为模板制备的介孔二氧化钛光催化还原Cr(Ⅵ)的研究

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

为提高二氧化钛(TiO_(2))光催化效率,以硫酸水解法制备的纤维素纳米晶体(cellulose nanocrystals,CNC)为模板剂,采用酸水解法后高温煅烧制备介孔二氧化钛(C-TiO_(2))。采用扫描电镜、透射电镜、X射线衍射和低温N 2吸附-脱附手段对催化剂进行表征分析。结果表明,C-TiO_(2)粒子无明显团聚现象、粒径分布均匀,且具有良好的孔隙结构,平均孔径在12.03~23.03 nm,且随焙烧温度的升高而增大。CNC的加入有效抑制锐钛矿相向金红石相转变,使C-TiO_(2)的光催化活性显著提高。以K 2Cr 2O 7为铬源,在光催化反应器中进行还原实验,600℃焙烧的C-TiO_(2)表现出最高的光催化活性,1 h内对Cr(Ⅵ)的还原率达到99.24%。

In order to improve the photocatalytic efficiency of titanium dioxide(TiO_(2)),mesoporous titanium dioxide(C-TiO_(2))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 N 2 adsorption-desorption at low temperature.The results showed that C-TiO_(2) 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-TiO_(2) was significantly improved.Using K 2 Cr 2 O 7 as chromium source,the reduction experiment was carried out in the photocatalytic reactor.C-TiO_(2) roasted at 600℃showed the highest photocatalytic activity,and the reduction rate of Cr(Ⅵ)reached 99.24%within 1 h.