Production of activated carbons from technical lignin as a promising pathway towards carbon emission neutrality for second-generation (2G) ethanol plants

Technical lignin (TL) is a solid waste generated in industrial activities including pulp and paper mills and second-generation (2G) biorefineries. After isolation processes, TL is available in large quantities and has favorable compositional characteristics to produce high-performance activated carbons (ACs), such as low amount of residual carbohydrates, high reactivity due to the presence of different functional groups, and high aromatic carbon content. The value of the AC market is projected to reach US$ 7 billion by 2028, led by the water treatment sector. This work provides a brief overview of the status quo in the production of new adsorbents from TL, focusing on biorefineries, together with a bibliometric and patentometric survey. This evidenced a scarcity of publications on this topic, with the primary focus being on chemical modification of TL. A notable increase was observed in the production of ACs for electrochemical applications. Only a few patents were found on the subject, with China predominating technological development in this area. The findings revealed a technical-scientific-economic potential that has been largely unexplored, as no TL-derived AC from 2G biorefineries has yet been produced and applied in water treatment. Hence, there is excellent potential for the wider commercialization of AC produced from TL, representing an excellent opportunity to recycle TL and support the bio-based circular carbon economy, while also contributing to carbon emission neutrality. The marketing of high-performance ACs produced from TL could make biorefineries more profitable and less sensitive to market price fluctuations, while becoming carbon-neutral multiproduct platforms. [Display omitted] •Technical lignin (TL) has untapped technical-scientific-economic potential.•Production of activated carbon is a technological way to add value to TL.•Bibliometrics and patentometrics indicate a scarcity of value-added TL products.•Biorefineries as key contributors to carbon neutral emissions in the energy sector.•New opportunities and challenges identified for excess TL in 2G ethanol plant.