Lignin is an important renewable resource that could substitute fossil feedstocks. An electrochemical depolymerisation of lignin generating aromatic compounds is possible by using a deep eutectic solvent.

The controlled depolymerization of lignin is a promising approach for the generation of value-added compounds from biomass.

Products from lignin electro-oxidation are in situ extracted by MIBK in emulsion phase.

Facing the challenge of lignin valorization is one of the unsolved key steps for a sustainable and economically feasible biorefinery. Several processes were developed with the aim of producing value-added compounds from lignin. Thermal, enzymatic, and catalytic processes represent common techniques for lignin valorization. However, expensive catalysts or enzymes and harsh conditions hampered the implementation of these methodologies on an industrial scale. Here, we propose the utilization of a simple "swiss-roll" electrochemical reactor for the production of valuable carboxylic acids. We showcase that production of phenolic compounds, such as vanillin, is hindered by the electrochemical mechanism. Additionally, electrochemical stability experiments of possible products showed high reactivity of vanillin against the low reactivity of mono-and dicarboxylic acids. Simultaneously, the electrochemical process leads to stable carboxylic acids with high yields of 6.4, 26.8, and 4.2 % for oxalic, formic, and acetic acids, respectively, thus representing a competitive alternative to the catalytic and hydrothermal degradation process for the production of carboxylic acids.

Lignin valorisation via electrochemical depolymerization is a promising approach for commercial application due to its moderate reaction conditions. However, there is no available kinetics model for this reaction. Conventional reaction kinetics equations are inadequate when used for lignin degradation because of the limited kinetics information with respect the reaction mechanism. We suggest to use population balance equations to predict the evolution of molecular weight distribution of lignin with time. Solving the low molecular weight (MW) population balance equations is carried out discretely whereas a continuous solution was implemented for the high MW. Additionally, the model accounts for a recombination reaction for the depolymerized species. The model is capable of predicting the molecular weight distribution of lignin as a function of electrochemical processing time. New experimental results are used to extract kinetics constants for different kraft lignin samples.