纳米TiO_2/凹凸棒石光催化复合材料的制备及其动力学

Preparation of Nano-TiO_2/Attapuleite Composite and Its Photocatalytic Kinetics

采用溶胶-凝胶法制备了纳米TiO2/凹凸棒石光催化复合材料,并对其进行了表征.XRD结果表明,复合材料为锐钛矿相和金红石相的混晶结构,HRTEM和SEM图像显示,在凹凸棒石表面均匀负载了一层纳米TiO2颗粒.实验考察了煅烧温度、催化剂用量及材料吸附性能对其光催化性能的影响,结果表明,600℃下煅烧制备的复合材料中TiO2晶粒尺寸为16nm,锐钛矿相含量87%.复合材料对甲基橙有较强的吸附性,吸附平衡常数Ka=0.00896L/mg,催化剂添加量为3g/L时光照2h对甲基橙的降解率达92%.光催化动力学方程符合Langmnir-Hinshelwood模型,二级动力学方程可很好地描述其降解规律:lnCt+0.00896Ct=0.4180.0197t.

XRD,HRTEM,EDS and SEM were used to analyze the formation of nano-TiO2/attapulgite photocatalytic composite prepared by sol gel method.XRD analysis showed that the composite was the mixture of anatase and rutile.HRTEM and SEM images showed that a uniform layer of TiO2 particles was loaded on the surface of attapulgite.The effects of calcination temperature,dosage of catalyst and adsorption properties on the photocatalytic properties of the composite were examined.The results showed that the grain size of TiO2 prepared at 600℃ was 16 nm and the phase content of anatase 87%.The composite had a stronger adsorption to methyl orange,and the adsorption equilibrium constant Ka=0.00896 L/mg.The kinetic equations of photocatalysis were in accord with Langmnir Hinshelwood model,second-order kinetic equations could describe the degradation well and photocatalytic kinetic equation was lnCt＋0.00896Ct=0.418-0.0197t.