复合光催化剂(TiO_2/多壁碳纳米管)制备工艺条件对甲基橙光催化降解动力学的影响

EFFECT OF THE PREPARATION CONDITIONS OF THE TiO_2/MWCNTs COMPOSITE PHOTOCATALYST ON THE PHOTODEGRADATION KINETICS OF METHYL ORANGE

采用溶胶-凝胶法在不同条件下制备了多壁碳纳米管(MWCNTs)负载纳米TiO2的复合光催化剂(TiO2/MWCNTs).以偶氮类染料甲基橙为模拟污染物,研究不同制备工艺参数的复合光催化剂对甲基橙的光催化降解动力学的影响.对TiO2/MWCNTs的表征结果表明,纳米TiO2较好地分散在多壁碳纳米管表面;随着温度的升高,复合光催化剂中纳米TiO2的晶型由锐钛矿型逐渐向金红石型转变,500℃时为两种晶型的混合相.进一步研究表明,催化剂和紫外光是甲基橙光催化降解的必要条件;甲基橙光催化降解反应遵循一级反应动力学,在焙烧温度500℃、焙烧时间3h、聚苯乙烯磺酸钠投加量为5g.L-1及多壁碳纳米管投加量为1.5%的条件下制备的复合光催化剂光催化降解甲基橙速率最快,其光催化反应速率常数为0.0073 min-1.

Composite photocatalysts（TiO2/MWCNTs）with TiO2 nano-particles attached on mutil-walled carbon nanotubes were prepared using sol-gel method under various conditions.Azo dye methyl orange was selected as the model pollutant to evaluate the effect of different preparation conditions of the composite photocatalysts on the photodegradation kinetics of methyl orange.Characterization of the TiO2/MWCNTs showed that nano-TiO2 was evenly coated on the surface of the multi-walled carbon nanotubes.The crystal of nano-TiO2 on the composite photocatalyst transformed from anatase to rutile as the calcination temperature increased,and it was a mixture of the two types of crystals at 500℃.Further study indicated that the catalyst and UV were both necessary for photocatalytic degradation of methyl orange.The photodegradation of methyl orange followed the first-order reaction kinetics.Using the composite photocatalyst prepared with 5 g·L^-1 polystyrene sulfonate sodium（PSS）,1.5% MWCNTs,500℃ calcination for 3h,the fastest degradation was achieved with a rate constant of 0.0073min^-1.