Emulsion electro-oxidation of kraft lignin

Abstract

Lignin is one of the most abundant bio-polymers present in nature and its valorization is still a challenge to an economically feasible biorefinery concept. The heterogeneity and scarce reactivity of lignin are significant hurdles to the development of new valorization processes. We propose an in situ extraction electrochemical depolymerization system. Kraft lignin dissolved in a deep eutectic solvent together with an extractant phase is able to form a stable emulsion. Electro-oxidation of the emulsion using a nickel or graphite electrode results in successful depolymerization and simultaneous fractionation of the products. Over-oxidation of the depolymerization products is anticipated to be suppressed upon swift extraction from the lignin phase into the extraction phase.