Construction Of Biocomposite Materials Based On Laccase-mediator System And Study On Its Catalytic Degradation Of Anthraquinone Dyes

accase is a copper-containing polyphenol oxidase that catalyzes the oxidation of phenolic and aromatic compounds.Named after the lacquer tree in which it was first found,laccase has long been found to be widely present in fungi,bacteria,insects and plants.At present,the main laccase that can be produced on a large scale is fungal laccase.The ability of laccase to bind to a mediator containing a specific electron donating group to form a lacase-mediator system(LMS)speeds up the laccase reaction rate and allows laccase to catalyse the oxidation of a wider range of substrates,ABTS being the most common synthetic mediator for laccase.Although LMS can enhance the redox ability of laccase,it is still at the laboratory stage and there are many problems and difficulties to be solved in its application.Firstly,the catalytic process of laccase and mediator is complicated and the application cost is high,and then it is difficult to recycle laccase and mediator after they have been put into the dye solution for use.Therefore,this study attempts to use the encapsulation method to immobilise laccase and its mediator on copper alginate carriers respectively,and optimise the immobilisation conditions to obtain a higher recycling decolourisation effect on reactive blue 19 dye,while using calcium alginate to adsorb copper ions and organic carbon from the reacted solution.In this thesis,the amount of laccase and ABTS used in immobilised laccase and immobilised ABTS were first investigated and the process conditions in laccase immobilisation were optimised based on the study by Pan Ting et al.at Shanghai Jiaotong University.At the same time,the elemental composition and structural information of the internal copper alginate were obtained using SEM,FTIR,EPR and EPMA to demonstrate the binding of ABTS and laccase in the internal copper alginate.Secondly,the effect of laccase and ABTS on the decolourisation of Reactive Blue 19 was compared under different conditions of free and immobilised laccase,and it was found that the immobilised laccase group had a higher decolourisation rate than the free laccase group and a better reaction stability.The immobilised ABTS was found to produce free radicals in air.In addition,this paper also compares the effect of copper alginate laccase based on copper sulphate and copper acetate on the cyclic degradation of active blue 19 based on the immobilised laccase@ABTS.Finally,further analysis of the immobilised laccase and immobilised ABTS degraded solutions was carried out by TOC,HPLC,mass spectrometry and atomic absorption,and 80% of the copper ions and TOC concentrations in the solutions were removed by calcium alginate.