TiO 2光催化降解2，4-二氯酚动力学及机理的研究

摘要

以TiO2作为催化剂，500 W汞灯作为光源，对水体中2，4-二氯酚（2，4-DCP）的光催化降解特性进行了研究。实验结果表明， TiO2光催化降解2，4-DCP效果较好，降解的最佳pH为7，催化剂的最佳投加量为200 mg· L-1。2，4-DCP的初始浓度越小，光催化的效率越高。在初始浓度为5 mg· L-1时，光催化1 h的降解率达90％。在实验的四种不同初始浓度（5 mg· L-1、10 mg· L-1、20 mg· L-1、40 mg· L-1）下，2，4-DCP的光降解速率常数近似与其初始质量浓度成一级反应动力学关系。结合高效液相色谱、气相色谱-质谱的测定结果以及Cl-、 COD的变化，认为2，4-DCP的主要降解过程为：脱氯-开环-矿化、中间产物相互作用-进一步矿化。%Photocatalytic degradation characteristics of 2,4-DCP by TiO2 was studied under 500 W mercury lamp.The experimental results showed that TiO 2 exhibited significantly photocatalytic action on 2 ,4-DCP.The optimal pH was about 7 and the best catalyst dosing quantity was 200 mg· L-1.The initial mass concentration of 2,4-DCP presented negative effect to photocatalysis efficiency.When the initial concentration of 5mg· L-1 , photocatalytic degradation of 1 h rate was 90%.Four different initial concentrations were 5 mg· L-1 , 10 mg· L-1 , 20 mg· L-1 , and 40 mg· L-1 , the photodegradation rate constant approximation of 2,4 -DCP and its initial mass concentration into a first order reaction kinetics.In combination with high performance liquid chromatography , gas chromatography -mass spectrometry determination results were as well as the change of Cl -and COD.The results showed that the main degradation process for 2 ,4-DCP were dechlorination-open loop-mineralization , and the intermediate interaction -further mineralization.