Optimization of a formic/acetic acid delignification treatment on beech wood and its influence on the structural characteristics of the extracted lignins

Background In order to replace petrochemicals by bio‐based lignin products in high value‐added applications, a formic/acetic acid treatment was adapted to beech wood ( Fagus sylvatica L.) for lignin extraction . Results Beech wood particles were delignified at atmospheric pressure by a formic acid/acetic acid/water mixture. Cooking time and temperature were optimized for delignification, pulp yield and 2‐furfural concentration. Response surface design analysis revealed that delignification yield increased with cooking time and temperature . Conclusion The multi‐criteria optimization of delignification was used to find the ideal cooking conditions (5 h 07 min, 104.2 °C) to maximize delignification (70.5%) and pulp yield (58.7%) and, to a lesser extent, minimize 2‐furfural production. Treatment conditions were found to influence the chemical structure of extracted lignins. Cooking time and temperature inversely influenced lignin molecular weights. © 2013 Society of Chemical Industry