Investigation on Enzymatic Oxidative Polymerization of Technical Soda Lignin

Enzyme, including laccase and peroxidase, catalyzed oxidative polymerization of technical bagasse soda lignin and low molecular weight ultra-filtrated kraft pulp lignin in methanol-water solution were studied. The weight average molecular weight of original macromonomer and polymerized lignin were characterized with alkaline size exclusion chromatograph system. Laccase treatment increased the molecular weight of both technical bagasse lignin and ultra-filtrated lignin up to 20 times in 24h. Compared to the low molecular weight ultra filtrated lignin, the reaction rate of bagasse lignin was consistant during the whole procedure. The reaction time and the laccase dosage were investigated to obtain the maximal molecular weight. The horseradish peroxidase treatment was a potential method for low molecular weight ultra filtrated lignin.