用溶剂热处理法制备TiO_2纤维及其光催化降解甲基橙的活性

Photocatalytic Reactivity of Methyl Orange Degradation over Fibrous Titania Prepared by Solvothermal Treatment

在不同温度下 ,用甘油常压热处理层状水合钛酸 (H2 Ti4O9·nH2 O)制备了TiO2 纤维 ,并用XRD进行了表征 .结果表明 ,经 6 0 ,15 0和 2 5 0℃甘油热处理后 ,样品的主晶相均为H2 Ti8O17,得到有较大比表面积和有微孔结构的TiO2 纤维 ;当处理温度为 15 0℃时 ,制得的TiO2 纤维比表面积由原来的 30m2 /g增大到 12 7m2 /g ,其中小于 1nm的微孔比表面积为 79m2 /g .以甲基橙为代表物 ,考察了TiO2 纤维的光催化活性 .与在空气中热处理相比 ,甘油常压热处理提高了TiO2 纤维的光催化氧化活性 ,其降解甲基橙的能力优于P 2 5 .

Fibrous TiO2 has photocatalytic activity and can be easily separated from the reaction system. Modification of the precursor, layered hydration titanic acid (H2Ti4O9 . nH(2)O), is an effective way to obtain fibrous TiO2 with high photocatalytic activity and low cost. H2Ti4O9. nH(2)O was prepared through vacuum drying at 60 degreesC for 24 h, after completely leaching K+ ions of K2Ti4O9 in a certain amount of water with pH= 1 by dripping HCl solution (1 mol/L). H2Ti4O9 . nH(2)O was dispersed in glycerine, and then was added in a round-bottom flask with reflux condenser. After dehydration at different temperatures for 24 h, fibrous TiO2 was obtained by filtration, scrubbing and baking drying. The XRD analysis showed that the samples by thermal treatment at 60, 150 and 250 degreesC were mainly H2Ti8O17 phase. At - 196 degreesC,the surface area, pore volume and pore size distribution of layered hydration titanic acid and fibrous TiO2 were determined by BET method. The surface area of H2Ti4O9 . 1.2H(2)O is 30 m(2)/g and the pore size distribution mainly covers the range from 1 to 5 nm. And it almost has no micropores. However, the micropores of 1 nm appear and the surface area of fibrous TiO2 increases to 127 m(2)/g, after thermal treatment at 150 degreesC. The photocatalytic activity was measured in a cylindric photochemical reactor with a 300 W middle-pressure mercury vapor lamp. The material of cold trap is fused-silica: The permeation intensity of light is 33 mW/cm(2). The experiment was proceeded in a water bath at 25 degreesC. The quantity of catalysts was 500 mg/L and the initial concentration of methyl orange was 20 mg/L. The variation of residual chroma was measured by spectrophotometry and compared with P-25. It was found that fibuous TiO2 with glycerine treatment has more capability of photocatalytic oxidation of the methyl orange than P-25 from Degussa.