Decolorization Of Azo Dyes By Laccase Immobilized On Silica: The Effect Of Particle Size And Pore Structure

Laccases belong to the family of blue multicopper oxidases and have great potentials in treatment to wastewaters due to their broader substrate specificities for polyphenols and aromatic amines as well as oxygen as benign oxidizing agent. With the development of immobilization techniques, using laccase repeatedly became true since the stability of laccase was improved a lot after immobilization. Silica nanomaterials are promising candidates for enzyme immobilization. In present study, nonporous Fe₃O₄/SiO₂ nanoparticles with different particle size and mesoporous SiO₂ supports with different pore size and pore structure were prepared for laccase immobilization and understanding the effect of the size and structure of support on the performance of the immobilized laccase towards the decolorization of azo dyes.The main work is as follows:?1? Preparing and characterizing nonporous Fe₃O₄/Si O₂ nanoparticles with different particle size for laccase immobilization;?2? Preparin and Characterizing two mesoporous SiO₂ nanoparticles for laccase immobilization, one was prepared with CTAB as template, the other using CTAB and P123 as binary templates;?3? Investigating the decolorization of Azophioxine by laccase immobilized on SiO₂ support with different particle size and different pore structure;?4? Investigating the operational stability of the immobilized laccase;?5? Investigating the electrochemical behavior of glassy carbon electrodes modified with immobilized laccase.The results suggest that SiO₂ supports show different performance for laccase immobilization and later dye decolorization when the difference in particle size or pore structure existed. Those nonporous SiO₂ supports with small particle size are more suitable for immobilization of laccase and getting excellent enzyme activity towards dye decolorization. The two kinds of mesoporous SiO₂ particles were used as the support of laccase, the laccase loading were similar, but the decolorization of azo dyes was much different, so the pore structure of the support affected the activity of laccase.