Fe/TiO2多相可见光Fenton反应降解阿特拉津研究

Heterogeneous Fenton reaction of Fe/TiO2 to the photo-catalytic degradation of atrazine under visible irradiation

为改善多相Fenton催化剂的催化活性及循环使用性能,以Fe(NO3)3为Fe源,TiO2为载体,制备了一种基于TiO2负载型的多相Fenton催化剂Fe/TiO2,对催化剂进行了SEM和XRD分析,考察了不同催化体系、初始pH值和H2O2投加量对阿特拉津降解效果的影响,并对其进行了反应动力学拟合。结果表明:Fe/TiO2含TiO2及α-Fe2O3两种晶型,负载Fe以α-Fe2O3形式高度分散在TiO2表面,未对TiO2粒径和形貌造成明显改变;Fe/TiO2在可见光及H2O2共存体系下催化效果最佳,Fe/TiO2可见光催化H2O2降解阿特拉津的效果要显著优于TiO2和Fe2O3,显示出负载Fe和TiO2之间存在明显的协同效应;在pH值3.00、H2O2浓度为1.6mmol/L和Fe/TiO2投加量为1g/L条件下,可见光催化反应30min,Fe/TiO2对阿特拉津的降解率达95%,并显示较好的循环使用性能;相较于传统Fenton反应,Fe/TiO2多相可见光Fenton体系拓宽了pH值适用范围,在初始pH=3.00~7.00时,反应30min对阿特拉津的降解率均可达到80%以上;Fe/TiO2多相可见光Fenton反应降解阿特拉津过程符合准一级动力学模型,在初始pH值为3.00和H2O2浓度为1.6mmol/L条件下反应速率常数最大,对阿特拉津的降解速度最快;实际应用中,控制溶液体系中的pH值为3.00,H2O2与阿特拉津物质的量之比为35∶1较为适宜。

This paper is inclined to make an exploration of the particular characteristic features of the heterogeneous Fenton catalyst Fe/TiO2 and its effect on improving the photo-catalytic degradation of atrazine as well as the photo-catalytic properties under visible irradiation based on Fe(NO3)3 by using TiO2 as substrate.For the said purpose,we have done an investigation on the photocatalytic degradation efficiency under the different catalytic conditions,such as the initial pH,the H2O2 dosage and the reaction kinetics with the catalysts being characterized by SEM and XRD.The results show that TiO2 and α-Fe2O3 are present in the prepared Fe/TiO2 in which Fe3+appear in the form of α-Fe2O3 highly dispersed on the surface of TiO2,with Fe3+loaded about1.0%.Moreover,the size and morphology of TiO2 remain the same basically,with the particle size of Fe/TiO2 being about 20-50 nm.On the other hand,the best catalytic effect of Fe/TiO2 can be observed and discovered under the visible irradiation and in H2O2 coexistence system,wherein the degradation of atrazine by Fe/TiO2 under the visible light irradiation and H2O2 can be going on a lot more efficiently than by TiO2 and Fe2O3,which shows that there may take place a significant synergistic effect between Fe3+and TiO2.What is more,the atrazine degradation rate of Fe/TiO2 can be made so high up as to 95% through 30 min visible photo-catalytic irradiation under the condition with a concentration of H2O21.6 mmol/L,at the initial pH of 3.00 and the Fe/TiO2 dosage of 1 g/L,under the acceptable recycling processing.Therefore,as compared with the traditional Fenton reaction,the Fe/TiO2 heterogeneous Fenton system should be broadened with its pH application range.Hence,with the solution's pH value varied from 3.00 to 7.00,it would be possible for the degradation rate of atrazine to achieve 80% 30 min later.Besides,the process of atrazine degradation by Fe/TiO2 heterogeneous Fenton reaction under the visible irradiation can be done in accordance with the pseudo-first-order kinetic model.The optimized conditions of atrazine degradation rate constant can be found and verified in the initial pH = 3.00 by adding H2O2 concentration of 1.6 mmol/L.Exactly speaking,in the experiment,proper conditions can be chosen as follows:pH = 3.00,with the mole ratio of H2O2 and atrazine being about 35:1.