Enhancement of lignin removal from pre-hydrolysis liquor for saccharide recovery via horseradish peroxidase treatment in the presence of Ca.

The removal of lignin is important to the recovery of saccharides from the pre-hydrolysis liquor (PHL) in kraft-based dissolved pulp production. A one-step process for lignin removal from PHL via treatment with horseradish peroxidase (HRP) in the presence of Ca was proposed, and its principle was studied. The results demonstrated synergy between HRP and Ca in lignin removal from PHL, whereas NH had little effect on lignin removal. HRP treatment in the presence of 60 mmol/L of Ca resulted in a lignin removal of 64.8% accompanied by a saccharide loss of 14.2%. HRP catalyzed both the polymerization and depolymerization of the lignin in the PHL. The HRP-catalyzed lignin polymerization rendered some lignin insoluble enabling it to be directly removed. The HRP-catalyzed depolymerization of lignin decreased its molecular weight with an evident increase in its carboxyl content. The insoluble complexes formed between the lignin with carboxyl and the Ca facilitated the removal of the depolymerized lignin.