Study On Degradation Mechanism Of 2,4-Dichlorophenol By Ultrasonic Cooperative Laccase

The chlorophenols are a class of persistent pollutants with high toxicity.Their existence and treatment in the environment have always been the focus of people's attention.2,4-Dichlorophenol(2,4-DCP)is selected as the target pollutant in this paper.The ultrasound-assisted laccase system was established and 2,4-Dichlorophenol was selected as the target pollutant.Firstly,the effects of different treatment conditions on the degradation rate of 2,4-dichlorophenol in water were studied,and the single treatment technology was compared with the combined treatment technology.Then the system was applied to the soil,the effects of different treatment conditions on the degradation rate of 2,4-dichlorophenol in the soil were studied and the single treatment technology was also compared with the combined treatment technology.Finally,the effect of ultrasound on laccase activity and structure was explored.Also,the degradation pathway of 2,4-dichlorophenol was explored.The main conclusions were as follows:(1)In solution,it was found that ultrasound can maintain the relative enzyme activity of laccase at a high level.Under the optimal conditions,ultrasound-assisted laccase technology could not only shorten the degradation time of 2,4-dichlorophenol,but also the degradation effect was more significant.The degradation rate of 2,4-dichlorophenol could reach 77.5% at 4h.(2)In the soil,it was found that ultrasound could not only accelerate the mass transfer of laccase,but also enhance the desorption of pollutants in the soil.Under the optimal conditions,ultrasound-assisted laccase technology could not only shorten the degradation time of 2,4-dichlorophenol,but also the degradation effect was more significant.The degradation rate of 2,4-dichlorophenol could reach 51.7% at 21 h.(3)Laccase solution was analyzed by fluorescence spectrometer and circular dichromatograph.It was found that proper ultrasonic conditions can make the spatial structure of laccase more orderly.Then the laccase activity was better maintained while exposing the active site of the laccase molecule.(4)In ultrasound-assisted laccase technology,2,4-dichlorophenol was analyzed by high performance liquid chromatography and gas chromatography-mass spectrometry.The intermediates of degradation of 2,4-dichlorophenol were found to be 2-chlorophenol,4-chlorophenol,phenol,benzoquinone,2-hydroxyhexane and 4-isopropylphenol.