TiO_2和ZnO光催化降解敌百虫的影响因素研究

Factors Influencing Photocatalytic Degradation of Trichlorfon by TiO_2 and ZnO

采用溶胶-凝胶法和水热法制备了Ti O2和Zn O,并运用紫外-可见光谱、X射线衍射、扫描电子显微镜和红外光谱对光催化剂进行表征。用制备所得的Ti O2和Zn O作为光催化剂,降解敌百虫有机磷农药,使用气质联用仪对降解结果进行分析,探究农药初始浓度、农药初始p H值、光催化剂投加量、光照时间及不同光源对敌百虫降解率的影响。光催化降解反应表明,敌百虫的降解率随着初始浓度的增加明显降低,随着光照时间的延长先增加后趋于平缓,碱性条件和汞灯照射有利于敌百虫的光催化降解。Ti O2和Zn O的最佳投加量均为100~150 mg·L-1,以Zn O为光催化剂,投加量在0~100 mg·L-1时降解率的增幅明显高于投加量在100~200 mg·L-1时,且实验结果表明,5个影响因素条件下,Ti O2的光催化降解活性均低于Zn O。

Photocatalytic degradation of pollutants has attracted increasing attentions recently. Due to their stability, wide band gap and high photosensitivity, photocatalysts TiO2 and ZnO have been widely applied in the degradation of various organic pollutants. In this research, TiO2 and ZnO were prepared by sol-gel and hydrothermal synthesis method. The band gaps of their nanoparticles were estimated by UV ab-sorption spectra(UV-vis). Their crystalline phases were confirmed by X-ray diffraction(XRD)and Fourier infrared spectroscopy(FT-IR), and their morphology were observed by scanning electron microscopy(SEM). The photocatalytic degradation of trichlorfon was investigated under different initial trichlorfon concentrations, operating pH, photocatalyst rates, irradiation time and light sources. Results showed that the degradation rate of trichlorfon decreased with increasing initial concentrations of trichlorfon, but it increased with prolonging irradiation time while slowed down at longer time. Alkaline condition and mercury lamp irradiation both enhanced the degradation rates of trichlorfon. The maximal degradation rate occurred at a rate of 100~150 mg·L-1 of photocatalyst. Under ZnO, the increases in the degradation rate of trichlorfon were much higher at 0~100 mg·L-1 than at 100~200 mg·L-1. The photocatalytic degradation efficiency of ZnO was higher than that of TiO2 under the same conditions.