In-situ extraction of depolymerization products by membrane filtration against lignin condensation

• DOI: 10.1016/j.biortech.2020.123530
• Publication Date: 2020-05-17T14:00:18Z
• Authors: Virginie Steinmetz; Maud Villain-gambier; Armand Klem; Isabelle Ziegler; Stéphane Dumarcay; Dominique Trebouet
• Keywords: Depolymerization; Membrane reactor

Catalytic depolymerization of lignin is a challenging process due to competitive repolymerization reactions. In this paper, the oxidative depolymerization of lignin was catalyzed by a commercial laccase both in a batch experiment and in a membrane bioreactor using the same catalytic conditions. The membrane bioreactor was previously optimized to reach high permeation flux (25 L.h-1.m-2) during lignin diafiltration. While the lignin was exclusively condensed in the batch experiment leading to high molecular weight macromolecules (from 9 to 16 kDa), its depolymerization was effective in the bioreactor producing fragments of less than 1 kDa thanks to the in-situ extraction of the reaction products. This paper demonstrates that the reactor configuration is playing an essential role in triggering or preventing lignin condensation. It also reports the first proof-of-concept demonstrating that in-situ membrane extraction of the reactive fragments of lignin from the bulk medium can be useful against detrimental repolymerization reactions.