Pt掺杂TiO_2/粉煤灰漂珠的制备及光催化降解特性

Preparation and photocatalytic degradation properties of Pt-doped TiO_2/fly ash cenosphere

以粉煤灰漂珠为载体、钛酸四丁酯为钛源、氯铂酸为铂源,采用溶胶凝胶法制备了Pt掺杂TiO_2/粉煤灰漂珠复合材料。采用XRD、UV-Vis、XPS、SEM、EDS等对其进行表征,以亚甲基蓝为目标降解物对其光催化活性进行了研究。结果表明,负载在漂珠表面的TiO_2是锐钛矿型;Pt的掺杂能够促使TiO_2的吸收边红移,产生可见光响应,但是,掺杂过量的Pt会导致光催化活性下降;Pt元素在TiO_2中是以Pt4+和Pt单质的形式存在;Pt的最佳掺杂量为1.5%,在加入量为0.5 g时,暗反应30 min、光催化180 min后对浓度20 mg/L、pH=11.8的亚甲基蓝溶液的降解率达94.1%;无机阴离子的加入有利于光催化反应速率的提高,但是过多的阴离子反而会对光催化反应速率产生抑制作用。

The Pt-doped TiO2/fl y ash cenosphere photocatalytic composite materials were prepared by sol- gel method with fly ash cenosphere as c a r r ie r, tetrab uty l titanate as t ita n ium source and chlo ro p la t in ic acid as platinum source. The samples have been characterized by X R D ,U V - V is ,X P S ,S EM and EDS. The pho-tocatalytic activity of the samples was studied using degradation o f methylene b lu e . The results showed that the Ti02 loaded on f ly ash cenosphere surface was anatase, the doping o f Pt could cause the red shift of the absorption edge of Ti02, and produce response to vis ib le l ig h t, however, excessive Pt doping would lead to the decrease of photocatalytic a c t iv i ty. Determined when the optimum doping amount o f Pt was 1.5% ,the dosage was 0. 5 g,af ter the dark reaction o f 30 min and the photocatalysis o f 180 m in , th e re-moval rate of methylene blue solution with the concentration o f 20 mg /L and pH =11.8 was 94. 1 % ,and the addition of inorganic anions was be ne fic ial to the improvement o f the photocatalytic reaction ra te , but the too much of anions could produce a negative effect on i t .