Abstract
The bio refinery initiative in the pulp and paper industry aims at diversifying their product offering including value added biomaterials from lignin. As an alternative to the chemical method using carbon dioxide and sulfuric acid, we have developed an electrochemical approach to precipitate lignin from black liquor while recovering caustic. Our approach, which is based on electrolysis of black liquor, reduces its alkalinity electrochemically to the point of lignin precipitation. It does not require any chemicals from an external source and generates no additional effluent complying with sustainability development. The technology offers an increased production capacity for a Kraft mill limited by the recovery boiler capacity or the recausticizing system. In this study, we investigated the fundamental electrochemical phenomena involved and the the effect of variables on the process performance in order to determine the best operating conditions in terms of current efficiency, energy consumption and caustic production.