Ce^(4+)/TiO^2溶胶对酸性藏青GGR的光催化降解

Photocatalytic degradation of acid navy blue GGR by Ce^(4+)/TiO_2 sol

以钛酸四正丁酯为前驱体,采用溶胶-凝胶法常温制备稀土离子Ce4+掺杂的TiO2溶胶,用以光催化降解酸性藏青GGR,探究掺杂对TiO2溶胶光催化活性的影响。研究Ce4+掺杂量、pH、溶胶浓度和染料初始浓度对溶胶光催化活性的影响。结果表明:未掺杂TiO2溶胶粒径为29.7nm,随Ce4+掺杂量增加粒径逐渐降低至22.4nm,粒径的减小使得TiO2粒子比表面积加大,光催化活性提高。染料降解率随掺杂量增加而提高,当Ce4+的掺杂量超过1.0%时,降解率下降,说明过量的掺杂会抑制TiO2的光催化活性。溶胶pH会影响溶胶中TiO2晶型和带电情况,pH为1-2时溶胶光催化活性最高。溶胶浓度低光催化反应体系中TiO2受激发产生的电子和空穴少,染料降解率低。染料初始浓度高紫外光透过率小,光能利用率低,染料降解速度慢。当溶胶pH为1-2,溶胶浓度0.2mol.L-1,染料初始浓度59mg.L-1时,未掺杂TiO2溶胶对酸性藏青GGR的降解率为64.5%,摩尔掺杂比1.0%的Ce4+/TiO2对染料的降解率达90.2%。掺杂使TiO2的光催化活性提高了25.7%。

The pure and Ce4＋ doped TiO2 nanoparticles were prepared by a sol-gel method at room temperature with Ti（OBu）4 as raw material. They were used to degradate the acid navy blue GGR. The influence of Ce4＋ dopant quantity, pH, sol concentration and initial dye concentration was studied respectively. The results showed that the sol particle size was decreased from 29.7nm to 22.4nm with increased Ce4＋ dopant quantity , reaction centers and particle surface area were increased and the composite of electrons and holes was also inhibited. All these played an axctive role in improving the sol photocatalytic activity. Degradation rate of dye was first increased and then decreased with increased amount of Ce4＋ , and the best molar ratio of Ce4＋ was 1.0%. As pH effected the crystalline and charge of TiO2, the sol enjoyed the highest pho- tocatalytic activity under strongly acidic conditions. The degradation rate of the acid navy blue GGR by Ce4＋/TiO2 （ratio of Ce4＋ to TiO2 1.0%,pH value 1-2, dye initial concentration 59mg ·L-1） reached 90. 2%. But the result of pure TiO2 sol was just 64. 5 %, indicating that doping made the degradation rate were increased by 25.7 %. The concentration of TiO2 involved in the photocatalytic reaction system decreased with sol concentration; and raised initial dye concentration will decrease transmittance,which were all bad to photocatalytic degradation.