Gao Shuai, Tian Guoyu, Fu Yingjuan, Wang Zhaojiang
State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China.
Polymers (Basel). 2023 Mar 29;15(7):1693. doi: 10.3390/polym15071693.
Apple wood waste (AWW), mainly tree trucks, is collectible lignocellulosic biomass from orchard rotation. The biorefinery of AWW is challenging because of the hard and dense structure. In the present work, chemical composition determination and microstructure observation was performed for the first time on AWW. Alkali-preimpregnation-assisted soda cooking (APSC) was developed to separate cellulose a pulp and lignin from AWW. APSC attained pulp yield of 34.2% at 23% NaOH, showing a 13.2% improvement compared to conventional soda cooking (SC). Fiber length analysis showed APSC-AWW pulp consisted mainly of medium and short fibers, which means blending with long-fibered pulp to enhance the physical strength of pulp sheets. A blend of APSC-AWW pulp and long-fibered pulp in the proportion of 80:20 attained comparable physical strength to hardwood kraft pulp. ASPC-AWW lignin was separated from spent liquor by acidification and then purified by dialysis desalination. The purified ASPC-AWW lignin showed a weight-average molecular weight of 4462 g/mol, similar to softwood kraft lignin but more uniform. Structural analysis revealed that ASPC-AWW lignin was composed of a syringyl unit (S), guaiacyl unit(G), and -hydroxyphenyl unit (H), and an S unit was dominant with an S/G/H ratio of 74.5:18.2:7.3. It is believed the utilization of fruit tree wood waste as the feedstock of biorefinery is attractive to countries without sufficient forestry resources. Furthermore, the developed APSC is based on conventional SC, which ensures the feasibility of an industrial application.
苹果木废料（AWW），主要是树干，是果园轮伐期可收集的木质纤维素生物质。由于其结构坚硬致密，AWW的生物精炼具有挑战性。在本研究中，首次对AWW进行了化学成分测定和微观结构观察。开发了碱预浸渍辅助苏打蒸煮（APSC）工艺，以从AWW中分离出纤维素浆和木质素。在23%氢氧化钠条件下，APSC的纸浆得率为34.2%，与传统苏打蒸煮（SC）相比提高了13.2%。纤维长度分析表明，APSC-AWW浆主要由中短纤维组成，这意味着需要与长纤维浆混合以提高浆板的物理强度。APSC-AWW浆与长纤维浆按80:20的比例混合，可获得与阔叶木硫酸盐浆相当的物理强度。通过酸化从废液中分离出ASPC-AWW木质素，然后通过透析脱盐进行纯化。纯化后的ASPC-AWW木质素重均分子量为4462 g/mol，与软木硫酸盐木质素相似，但更为均匀。结构分析表明，ASPC-AWW木质素由紫丁香基单元（S）、愈创木基单元（G）和对羟基苯基单元（H）组成，其中S单元占主导地位，S/G/H比例为74.5:18.2:7.3。据信，将果树木材废料用作生物精炼原料对森林资源不足的国家具有吸引力。此外，所开发的APSC基于传统的SC，这确保了工业应用的可行性。
