超声辅助硫酸水解法制备银杏果壳纳米纤维素及其特性表征

薛刚; 何易; 李小白; 章智; 张有做; 许光治

doi:10.13386/j.issn1002-0306.2020120006

超声辅助硫酸水解法制备银杏果壳纳米纤维素及其特性表征

Ultrasound-assisted Sulfuric Acid Hydrolysis Method for Preparation and Characterization of Nanocellulose from Ginkgo Nut Shell

摘要

摘要: 为充分利用银杏的工业生产副产物，以银杏果壳为原料，采用超声辅助硫酸水解法制备银杏果壳纳米纤维素（nanocrystalline cellulose isolated from ginkgo nut shell，NCC-GNS）。通过单因素实验研究了硫酸质量分数、反应温度和反应时间3个因素对NCC-GNS得率的影响，并应用正交试验进行优化，获得NCC-GNS的最佳制备条件。以常规硫酸水解法（未加超声辅助）制备的纳米纤维素（nanocrystalline cellulose，NCC）为对照，通过扫描电镜（scanning electron microscopy，SEM）、透射电镜（transmission electron microscopy，TEM）、Zeta电位和华体会（中国）光散射（dynamic light scattering，DLS）、X-射线衍射（x-ray diffraction，XRD）、傅里叶变换红外光谱（fourier transform infrared spectroscopy，FT-IR）、热重（thermogravimetric analysis，TGA）等分析超声辅助处理对NCC-GNS的影响。结果表明：超声功率120 W时，制备NCC-GNS的最佳条件为硫酸质量分数48%、反应温度60 ℃、反应时间25 min，最优条件下NCC-GNS得率为37.01%；超声辅助和常规硫酸水解法制备的NCC-GNS均为长棒型，尺寸无明显差异，超声辅助制备的NCC-GNS长度和直径的分布范围相对集中，长度80～180 nm、直径3.5～5.5 nm；超声辅助制备的NCC-GNS结晶度为88%，高于常规硫酸水解的75%；两种方法制备的NCC-GNS均具有较低的Zeta电位和有良好的热稳定性。综上，超声辅助硫酸水解法制备的NCC-GNS得率较高，获得的NCC-GNS结晶度高、热稳定性好，在生物质复合材料领域表现出良好的应用前景。

Abstract: In order to make full use of the by-products of industrial production of ginkgo, this study used ginkgo nut shell as raw materials and adopt ultrasonic-assisted sulfuric acid hydrolysis to prepare ginkgo nut shell nanocrystalline cellulose (nanocrystalline cellulose isolated from ginkgo nut shell, NCC-GNS). The effects of three factors (e.g. sulfuric acid mass fraction, reaction temperature, reaction time) on nanocellulose yield were investigated by single-factor tests, and orthogonal experiments were used to optimize them to obtain the best preparation conditions for NCC-GNS. Taking nanocrystalline cellulose (nanocrystalline cellulose, NCC) prepared by conventional sulfuric acid hydrolysis (without ultrasound assistance) as a control, analyzed the impact of ultrasound-assisted processing on NCC-GNS through scanning electron microscopy (SEM), transmission electron microscopy (TEM), Zeta potential and dynamic light scattering (DLS), X-ray diffraction (x-ray diffraction, XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), etc. The results showed that the optimal conditions for preparing NCC-GNS were sulfuric acid mass fraction of 48%, reaction temperature of 60 °C, reaction time of 25 min under the condition of ultrasonic power of 120 W. The NCC-GNS yield under optimal conditions was 37.01%. The NCC-GNS prepared by ultrasonic-assisted and conventional sulfuric acid hydrolysis methods were long rods with no significant difference in size. The length and diameter of the NCC-GNS prepared by ultrasonic-assisted were relatively concentrated with a length of 80~180 nm and a diameter of 3.5~5.5 nm. The crystallinity of NCC-GNS prepared by ultrasound was 88%, which was higher than 75% of conventional sulfuric acid hydrolysis. The NCC-GNS prepared by the two methods had lower Zeta potential and good thermal stability. In summary, the yield of NCC-GNS prepared by ultrasonic-assisted sulfuric acid hydrolysis was high, and the obtained NCC-GNS had high crystallinity and good thermal stability, which was expected to have better applications in the field of biomass composite materials.