Lignin degradation in cooking with active oxygen and solid Alkali process: A mechanism study

Non-phenol structure in lignin is difficult to be degraded under alkaline conditions, thus limiting the delignification efficacy in many pretreatment technologies . Intriguingly, the non-phenol structures can be degraded into low-molecular-weight products in cooking with active oxygen and solid alkali process. Herein, model compounds were adopted to investigate the degradation mechanism of lignin non-phenol structure under same conditions. Two pathways of converting the non-phenol structure to degradable structures are found: 1) After the C α -C β bond cleavage at the lignin side chain, the benzoic structure intermediates are degraded; 2) After hydrolysis of the aryl-ether bond, the phenol structure intermediates are then degraded. Moreover, the degradation of the phenol structure intermediates will further promote the hydrolysis of the ether bonds, thus resulting in the improvement in the delignification process. This work describes a novel pathway in lignin oxidation degradation and helps to understand the chemistry of lignin degradation process in related alkaline oxidation pretreatment technologies .