The Synergistic Action Of Electro-Fenton And White Rot Fungi In The Degradation Of Lignin

Because of its specific structure,lignin is difficult to degraded effectively in nature.So that lignin is one of the important factors of the pollution in the environment.Most papermaking industries use plant fibers as raw materials,and the lignin will be discharged in the form of papermaking black liquor finally.At the same time,lignin is also the main component in crops and other waste straws.Therefore,the degradation of lignin has become the key to control such pollution.However,due to the unique spatial structure of lignin,the single use of white rot fungi to degrade lignin will take time and have high environmental requirements.The system that cooperates with Electric-Fenton has a more significant effect of degradation.In this study,a synergistic system of composite cathode Electric-Fenton and white rot fungi was used to degrade lignin.First,the comprehensive performance of the composite cathode material in the synergistic system of Electric-Fenton and white rot fungi was studied.According to the influence of white rot fungus growth and lignin degradation rate under Electric-Fenton,the most suitable composite cathode material was selected from activated carbon fiber,unidirectional carbon fiber and graphite felt.Secondly,the effects of the white rot fungi growth,lignin degrading enzyme secretion and lignin degrading rate under voltage of 6 white rot fungi including Phanerochaete Chrysosporium,Coriolus versicolor,Lentinus Edodes,Pleurotus eryngii,Pleurotus ostreatus and Ganoderma Lucidium were studied.Finally,a synergistic system of Electric-Fenton and white rot fungi was constructed.Through the study of the white rot fungi growth and lignin-degrading enzymes,the mechanism of cooperative degradation was explored.The results of this study are as follows:?1?Compared with the white rot fungus culture system using unidirectional carbon fiber and graphite felt as the cathode material,the white rot fungus has the highest growth OD under the culture system using activated carbon fiber,which Coriolus versicolor reaches 0.618,and the amount of adhesion to white rot fungi of activated carbon fiber was significantly lower than that of the other two materials during the white rot fungi growth.In addition,the activated carbon fiber promotes lignin degradation rate significantly better than the other two.At 5 V,the lignin degradation rate reaches about 22%.?2?The results of the white rot fungus screening showed that the growth conditions of Phanerochaete Chrysosporium,Coriolus versicolor and Lentinus Edodes,were significantly better than the other three.At 96 h,the OD of Phanerochaete Chrysosporium,Coriolus versicolor and Lentinus Edodes under 4 V were 0.585,0.618 and 0.551,which were significantly higher than Pleurotus eryngii,Pleurotus ostreatus and Ganoderma Lucidium.The enzyme activity also showed that the three enzyme activities of Phanerochaete Chrysosporium,Coriolus versicolor and Lentinus Edodes were significantly higher than Pleurotus eryngii,Pleurotus ostreatus and Ganoderma Lucidium.In the degradation of lignin by the synergistic system of Electric-Fenton and white rot fungi,the degradation rate of lignin by 6 white rot fungi was significantly different.Phanerochaete Chrysosporium,Coriolus versicolor and Lentinus Edodes are more than 10%higher,and the lignin degradation rate in the range of 0 V-4 V increases with increasing voltage.?3?Exploring the degradation mechanism of lignin degration by the synergistic system of Electric-Fenton and white rot fungi,the results show that the lignin degradation efficiency?82?89%?of the synergistic systems at 4 V was higher than that of a control at 96 h post inoculation.Furthermore,the H₂O₂produced and phenolic lignin converted in the system can significantly enhance the efficiency of ligninolytic enzymes so that considerably increased enzyme activity was obtained by the synergistic action of Electro-Fenton processes and white rot fungi.¹³C NMR spectroscopy revealed that aromatic structure units?103-162 ppm?were effectively degraded by three fungi.?4?The study shows that the combination of Electro-Fenton processes and white-rot fungi treatment significantly improved the lignin degradation efficiency,which established a promising strategy for lignin degradation and valorization.