Exploring the effect of lignin on the chemical structure and microstructure of Chinese fir wood by segmental delignification

This study proposed a new method for the rapid and uniform removal of lignin components from wood, which was applied to abundant fast-growing Chinese fir. Based on the lignin removal using acidic NaClO₂, the impregnation process with positive pressure-negative pressure circulation was used to promote the reaction. Using this method, the time of the impregnation and discharge of lignin was shortened, and the complete cellulose skeleton of Chinese fir can be easily prepared. The lignin removal effect on crystalline structure and chemical structure was discussed. It was deduced that the macroscopic morphology of Chinese fir was complete and the end face did not crack under the positive–negative pressure cycles. The FTIR showed that the proposed method can better reduce the damage of holocellulose by delignification treatment and uniform and efficient removal of lignin. The relative crystallinity gradually increased with the increase in the cycle number, achieving a selective delignification effect. This method achieved accurate regulation of the lignin removal effect, promoted the utilization of Chinese fir in functional materials, and provided a cellulose wood-based template for the high-value utilization of Chinese fir.