Degradation kinetics of wastewater from papermaking on nanosized titanium dioxide surface modified with Methylene Blue
亚甲基蓝表面修饰纳米TiO2降解造纸废水动力学

Nanometer size titanium dioxide modified with Methylene Blue(TiO2-MB)was prepared using chemical adsorption method.Through surface modification,the formation of TiO2-MB results in a red shift of UV-Vis reflectance spectra,towards the visible region,up to 575 nm.The influences of amount of catalyst,irradiation time and pH value on the photocatalytic degradation of papermaking wastewater on TiO2-MB were also studied.The adsorption and photocatalytic oxidation proceses of wastewater from papermaking on nano-TiO2-MB were studied.The results indicate that the adsorption law of wastewater from papermaking on nano-TiO2-MB fit in well with the Langmuir model and Freundlich model.Thermodynamic study showed the adsorption was an endothermic process.The photodegradation fits in with Langmuir-Hinshelwood kinetic mode.The optimal photodegradation conditions were obtained: catalyst amount of 3.0 g/L,papermaking wastewater’s pH value of 2.0,and irradiation time of 80 min with 160 W of high-pressure mercury lamp,the COD removal rate of papermaking wastewater reached 94.7%.The photodegradation efficiency was higher than the adsorption efficiency.The used photocatalyst could be used for the eighth time with high efficiency.