纳米TiO_2光催化降解直接耐晒蓝的研究

STUDIES ON THE PHOTODEGRADATION OF DIRECT BLUE ON NANOSIZED TITANIA

利用溶胶 凝胶法以钛酸四丁酯制备TiO2 纳米粉末 ,考察不同温度焙烧的TiO2 催化剂对直接耐晒蓝的光催化降解性能 ,并用XRD和TEM对催化剂进行了表征 .结果表明 ,40 0— 5 5 0℃焙烧的TiO2 使直接耐晒蓝溶液的颜色逐渐褪去 ,最后将苯环结构分解 ,6h时染料溶液CODCr降解率为 88% .降解产物中除含极微量有机酸外 ,其余均为无机物 .当TiO2的焙烧温度为 475℃时 (颗粒大小为 1 0— 2 0nm) ,反应速率最大 ,为 0 0 1 86min- 1 ,分别比焙烧温度为 40 0℃和 5 5 0℃时的反应速率大 6 8和 7 1倍 .当体系起始pH值为 4 5 0— 7 5 2时 ,反应速率随pH值的降低而增大 .

The ultra fine nanosized TiO 2 photocatalysts were prepared by the hydrolysis of Ti(OC 4H 9) 4 solution and calcined at different temperatures.The catalysts were characterized by XRD,TEM.Direct blue was photodegradated rapidly in the presence of self prepared TiO 2 particles calcined from 400-550℃. It has been proved that the principal ultimate products of the photodegradation of direct blue are CO 2,H 2O and other mineral compounds.We have also confirmed that the catalyst calcined at 475℃ which was in anatase phase showed the highest photoactivity.In order to study the influence of the initial pH value of solutions on the photoassisted reaction,four different solutions were tested(pH value was 4 50,5 24,6 45 and 7 52,respectively).The result showed that decreasing pH value is in favor of the reaction.In the meanwhile,the degradation efficiency of COD Cr of the solution is 88%.All these results indicated that this process has potential applications to the elimination of direct blue in the wastewater.