纳米TiO_2-活性炭的制备及光催化脱汞初探

PRE-INVESTIGATION OF NANOSTRUCTURED TiO_2-ACTIVATED CARBON COMPOSITE FOR PHOTO CATALYTIC OXIDATION REMOVAL OF MERCURY VAPOR

采用溶胶凝胶法以活性炭(AC)为载体,制备纳米TiO_(2-)活性炭复合物(TiO_(2-)AC).采用X射线衍射仪(XRD),场发射扫描电镜结合X射线能谱分析仪(FSEM-EDX)对TiO_(2-)AC复合物进行表征。在波长为253.7 nm的紫外光照射下进行TiO_(2-)AC光催化氧化脱除单质汞试验。结果表明,复合物表面TiO_2纳米粒子尺寸可控制在30 nm左右;热处理温度的升高促进TiO_2晶粒的生长及相变,复合物中TiO_2锐钛矿相向金红石相转变的温度在500～700℃之间;负载锐钛矿型TiO_2的复合物较金红石型复合物显示出更强的光催化脱汞效果。TiO_(2-)AC能够达到预期的结合TiO_2光催化氧化性能与活性炭强吸附能力的效果,脱汞性能显著,具有广阔的应用前景。

A process by sol-dip method has been developed to synthesize a novel composite catalysts of activated carbon coated with nano-scale TiO2 particulates（TiO2-AC）.X-ray diffraction spectroscopy（XRD） and field scanning electron microscopy with energy dispersive X-ray analysis （FSEM-EDX） were utilized to characterize the catalysts.Photocatalytic oxidation experiments with the catalysts for mercury vapor removal were carried out in a lengthways reactor with on-line monitor under UV irradiation at the wave length of 253.7 nm.The results show that it is effective to load TiO2 particulates at the size about 30nm on porous activated carbon by sol-gel method.The increase of the temperature in heat treatment process of the composites promotes the crystalization of TiO2, the transformation of TiO2 from anatase to rutile happens between 500℃and 700℃.The composite loaded with TiO2 in anatase phase indicates remarkably high photocatalytic removal rate of mercury vapor,more effective than the one coated with rutile phase,exhibiting synergistic adsorption and photo-oxidation ability.