TEMPO氧化-高压均质联用制备柑橘纳米纤维素及其性质表征

以柑橘皮渣为原料,采用2,2, 6,6-四甲基哌啶-1-氧自由基(TEMPO)介导氧化联合高压均质法制备柑橘纳米纤维素,研究次氯酸钠添加量(5、25、50mmol/g)对柑橘纳米纤维素长径比、形貌结构、理化性能等特性的影响。结果表明:随着次氯酸钠质量摩尔浓度的增加,柑橘纳米纤维素的直径和长度都逐渐缩短,并在50mmol/g时长度(150.57±24.99)nm]与直径(2.74±0.29)nm]达到最短。扫描电镜与红外光谱分析结果表明:随着氧化剂质量摩尔浓度的升高,柑橘纤维中的木质素、半纤维素被水解,柑橘纤维表面呈现出越来越粗糙的结构。X射线衍射和热重分析显示:氧化均质处理提高了柑橘纳米纤维素的结晶度和耐热性,且纤维素的Ⅰ型晶型未遭到破坏。理化性质分析表明:氧化均质处理可有效提高柑橘纳米纤维素持水力、持油力、胆固醇吸附力和葡萄糖吸附力,并在次氯酸钠质量摩尔浓度为50mmol/g时表现出最强的吸附力。纳米化的柑橘纤维素具有良好的功能特性,研究以期为柑橘皮渣的再利用提供一定的科学依据。

Preparation of Citrus Nanofibers by TEMPO Oxidation-High Pressure Homogenization and Its Characterization

Using citrus peels as raw materials, citrus nanofibers were prepared successfully by the method of the combination of 2,2, 6,6-tetramethylpiperidine-1-oxygen radical (TEMPO) oxidation and high pressure homogenization. Meanwhile, the effect of various molality of NaClO (5mmol/g, 25mmol/g, 50mmol/g) on the aspect ratio, morphology, physicochemical properties of citrus nanofibers were investigated. The results showed that with the increase of NaClO molality, the diameter and length of citrus nanofibers were gradually decreased. When the molality of NaClO was 50mmol/g, the diameter and length reached to the shortest, which were (150.57±24.99)nm and (2.74±0.29)nm, respectively. Results of scanning electron microscopy and FTIR spectra revealed that the lignin and hemicellulose in citrus fibers were hydrolyzed in the reaction of TEMPO oxidation with the increase content of NaClO, resulting in a rougher surface. The spectra of X-ray diffraction and thermogravimetry exhibited that TEMPO oxidation and high pressure homogenization treatment could improve the crystallinity and heat resistance of citrus nanofiber, and the formed cellulose I crystals was not destroyed. The analysis of physical and chemical properties of citrus nanofibers showed that the water holding capacity, oil holding capacity, cholesterol adsorption capacity and glucose adsorption capacity could be effectively improved after the TEMPO oxidation and high pressure homogenization treatment. And the strongest adsorption capacity was achieved when NaClO molality was 50mmol/g. The results showed that nano-sized citrus fiber possessed excellent functional properties, and this paper hoped to provide a scientific basis for the reuse of citrus peel.