Fe^(3+)掺杂介孔TiO_2催化降解甲基橙

Degradation of methyl orange catalyzed by Fe^(3+) -doped mesoporous TiO_2

以表面活性剂十六烷基三甲基溴化铵醇溶液所形成的柱状胶束为模板剂,钛酸四丁酯为原料,经水解沉淀、晶化、沉降、抽滤、干燥及焙烧工艺制备出了介孔TiO_2固体催化剂。通过离子掺杂方法,用Fe(NO_3)_3溶液对介孔TiO_2掺杂,经搅拌、煮沸、晶化、蒸发、干燥及焙烧工艺,制备出了不同物质的量比的Fe^3/TiO_2催化剂。以甲基橙模拟染料废水,考察pH、催化剂用量、过氧化氢用量、催化剂Fe^3与TiO_2物质的量比和光照时间等因素对催化剂的催化性能的影响。结果表明,适量掺有Fe^3的催化荆Fe^3/TiO_2有利于太阳光催化甲基橙的效果,当甲基橙浓度为10 mg·L^(-1)、Fe^3与TiO_2物质的量比为0.000 5、催化剂用量为0.8 g·L^(-1)、过氧化氢为0.55 mol·L^(-1)、pH=3并且太阳光直接照射20 min,脱色率达到96%。根据Languir-Hinshelwood动力学方程,近似推导出不同物质的量比Fe^3/TiO_2催化剂光催化降解甲基橙的动力学方程,并得出Fe^3与TiO_2物质的量比为0.0005时的Fe^3/TiO_2催化剂,有最大宏观速率常数值,K_0为0.162 35 min^(-1)。

Using the cylindrical micelles formed by surfactant cetyltrimethylammonium bromide alcohol solution as the template and tetrabutyltitanate as the starting material,mesoporous TiO_2 catalysts were prepared through hydrolysis/precipitation,crystallization,sedimentation,vacuum filtration,drying and calcination steps.The as-prepared mesoporous TiO_2 was doped by Fe(NO_3)_3 through stirring,boiling, crystallization,vaporization,drying and calcination steps and as a result,mesoporous TiO_2 catalysts with different Fe^(3+) /TiO_2 ratio were prepared.Influences of different factors,i.e.,pH value,dosage of the catalyst,amount of H_2O_2,Fe^(3+) /TiO_2 ratio and illumination time,on catalytic behaviors of the catalysts were investigated,using degradation of methyl orange solution as probe reaction.The results indicated that appropriate doping of Fe^(3+) /TiO_2 favored the photocatalytic degradation of methyl orange under solar irradiation;methyl orange degradation rate of 96% was attained under the following condition:methyl orange concentration of 10 mg·L^(-1),rc(Fe^(3+)):n(TiO_2) =0.000 5,catalyst dosage 0.8 g · L^(-1),hydrogen peroxide concentration of 0.55 mol · L^(-1) ,pH =3,illumination time of 20 min.Kinetic equations of the catalysts with different Fe^(3+) /TiO_2 ratio for photocatalytic degradation of methyl orange were approximately deduced via Languir-Hinshelwood equation,with the catalyst with n(Fe3+):n(TiO_2) of 0.000 5 having the maximum macroscopic rate constant K_0,equal to 0.162 35 min^(-1) .