关键词: 苎麻纤维, NHPI, 漆酶, 氧化脱胶, 断裂比功, 工艺优化

Abstract: " China, as a global powerhouse in bast fiber textiles, ranks first in the world in both the cultivation of bast crops and textile processing. Its bast textiles hold an absolute quantitative advantage in the global market. However, ramie fibers possess unique physical characteristics, such as a coarse and harsh hand feel, which are primarily caused by the presence of non-cellulosic substances like pectin, hemicellulose, and lignin. These substances adhere between or on the surface of cellulose, causing the fibers to become glued and entangled, significantly reducing their spinnability and the quality of the final product. Therefore, ramie fibers must undergo degumming before spinning. Traditional degumming methods mainly rely on chemical processes, such as acid and alkali treatments, which, although capable of producing fibers with excellent properties, suffer from drawbacks such as lengthy processes, high energy consumption, severe pollution, and large water usage. To address these issues, this paper proposes a novel hydrogen peroxide/N-hydroxyphthalimide (NHPI)/laccase catalytic oxidation system, aiming to shorten the process flow, reduce energy consumption, and enhance the mechanical properties of the fibers. In this study, four different treatment systems were initially established, including H2O2/NHPI, H2O2/laccase, NHPI/laccase, and H2O2/NHPI/laccase systems. The effects of these systems on the tensile properties of ramie fibers were compared and analyzed, and the oxidation mechanism of the H2O2/NHPI/laccase system was thoroughly investigated using 13C nuclear magnetic resonance (NMR) technology. Subsequently, through single-factor experiments and significance analysis, the influences of factors such as NHPI concentration, laccase concentration, H2O2 concentration, reaction temperature, reaction time, and pH value on fiber properties were explored. The process parameters were then optimized using a response surface methodology. The results showed that the H2O2 concentration, NHPI concentration, and pH value significantly affected the specific breaking work of ramie fibers. The optimal conditions for the oxidative degumming process were found to be: 11.04 g/L H2O2, 5 g/L laccase, 0.73 g/L NHPI, pH 4.77, temperature 55 °C, and time 20 min. The optimal conditions for the alkali treatment process were: 6 g/L NaOH, 2.5 g/L Na2SO3, 2 g/L Na2SiO3, temperature 100 °C, and time 60 min. Finally, this paper presented a comparative analysis between oxidative degumming and traditional alkali degumming in terms of fiber properties, reaction time, and energy consumption. The results indicated that the fineness of the ramie-refined dry fibers obtained through the oxidative degumming process was comparable to that of traditional alkali degumming. Moreover, the specific breaking work of the fibers from oxidative degumming was 0.133 cN/dtex, which was 12.7% higher than that of traditional alkali degumming and 18.0% higher than that of the process involving only alkali boiling without oxidation. Additionally, the total reaction time was reduced to 80 minutes, representing a 73% reduction compared to traditional alkali degumming, and the energy consumption at high temperatures was reduced by three-quarters. Characterization of the degummed ramie fibers using SEM, FTIR, and NMR methods revealed that after H₂O₂/NHPI/laccase oxidative treatment, the C6 primary hydroxyl groups of cellulose were oxidized, and non-cellulosic components were effectively removed, resulting in fibers with a smooth and unbonded surface. In conclusion, the H2O2/NHPI/laccase oxidative degumming method offers the advantages of short reaction time, low energy consumption, and high specific breaking work of the fibers, demonstrating significant potential for application in ramie degumming."

Key words: "ramie fiber, NHPI, laccase, oxidative degumming, specific breaking work, process optimization "