Enhancement of lignin removal from poplar prehydrolysis liquor by manganese peroxidase-induced polymerization

Abstract

The removal of lignin from prehydrolysis liquor (PHL) is important for the effective use of saccharides. Manganese peroxidase (MnP) was used for treating PHL to separate the lignin through the use of activated carbon (AC). The effects of MnP on lignin removal were monitored and the reaction mechanism was investigated. It was found that MnP converted the phenolic hydroxyl groups of lignin into phenoxy radicals, leading to lignin polymerization by coupling with β-O-4, β-β, and β-5 bond types, thus enhancing lignin adsorption by AC within the PHL. The combination of MnP and AC treatment led to the 65.71 % removal of lignin, with an increase of 70.68 % compared to the AC-treated PHL. The saccharide contents were largely unaffected by MnP, while the total xylose yield was 97.76 %. Furthermore, the total high heating value of AC after adsorption was 71.12 MJ·kg−1.