High purity lignin from untreated larch bark: an efficient green methodology for lignin valorization and low-value by-product mitigation

Increasing concerns toward climate change and fossil fuel-based products have opened the race toward viable alternative feedstocks, which could be utilized as alternatives for omnipresent chemicals such as fuels and polymers. Lignin is among one of the most promising candidates. Besides its promising chemical characteristics, it has also been put in the spotlight due to its economic potential for biorefinery profitability and waste reduction. As the timber industry has to fight a constantly growing larch bark by-product stream we decided to investigate its potential capacity as valuable source of biopolymers. Deep eutectic solvents due to their biodegradability, reusability and efficiency have been chosen as the extraction method of choice. The reaction parameters were optimized resulting in a very high lignin yield of 93%. Furthermore, the work-up process was investigated with a focus on quantitative chemical recycling and potential for upscaling to industrial scale.