Structural changes of bamboo-derived lignin in an integrated process of autohydrolysis and formic acid inducing rapid delignification

Bamboo chips were efficiently fractionated using an integrated process of autohydrolysis and formic acid to induce rapid delignification. Autohydrolysis pretreatment facilitated oligosaccharide production, while the subsequent rapid-delignification using formic acid at a low liquid/solid ratio with a relatively short reaction time allowed obtaining cellulose fibers and lignin. The major inter-unit linkages of side-chain in lignin were cleaved during the combined fractionation process. The lignin fraction exhibited higher purity, more phenolic OH groups, less condensed phenolic OH groups, and higher syringyl/guaiacyl ratio (S/G) as compared to MWL and formic acid lignin from the direct formic acid delignification. These results indicate that the combined fractionation process presents a promising approach to the commercial utilization in the biorefinery industry.