Efficient delignification of poplar and Chinese fir wood using a peroxyacetic acid/hydrogen peroxide system

Abstract The efficient removal of lignin is crucial for process optimization, as it enhances the exposure of polar groups in wood and provides interfacial binding sites for subsequent material modifications. In this study, an environmentally friendly peracetic acid/ hydrogen peroxide system was employed to delignify fast-growing wood. The results indicated mass loss rates of 30.7% for poplar and 31.3% for Chinese fir, with corresponding decreases in relative lignin content by 95.3% and 87.2%, respectively. Additionally, the specific surface area increased by 6.4% in poplar and 30.9% in Chinese fir. The relative crystallinity was enhanced by 31.2% in poplar and 15.7% in Chinese fir, and the O/C ratio increased by 29.6% and 19.7%, respectively. Microsocopic morphological analysis revealed noticeably thinner and slightly collapsed cell walls in the treated samples. The disappearance of lignin-specific peaks at 1507 cm −1 , 1460 cm −1 , and 1264 cm −1 confirmed the effective removal of lignin. Additionally, delignification resulted in a lower pyrolysis temperature, increased surface brightness, and reduced color variation. Due to the differences in internal structures and chemical compositions between poplar and Chinese fir, the effects of lignin removal varied, leading to significant changes in their physicochemical properties. These findings provide a theoretical foundational for lignin removal from wood and support future efforts in wood functionalization.