催化剂预加载Fenton氧化法微纤化纤维素的制备

以溶解浆为原料,采用催化剂预加载Fenton氧化协同高压均质法制备微纤化纤维素(MFC)。探讨了过氧化氢用量、催化剂七水硫酸亚铁用量、反应温度和反应时间对氧化效率的影响,并对氧化后纤维的微观形貌、化学结构变化及MFC微观结构、结晶度、热稳定性进行了表征。结果表明,催化剂预加载Fenton氧化法可显著提高氧化纤维中的羧基和醛基含量,降低纤维素聚合度和Zeta电位,增大纤维之间的静电斥力,利于后续的均质处理。在浆浓25%、过氧化氢用量0.15 g/g浆、七水硫酸亚铁用量1.5 g、pH值3、反应温度45℃、反应时间120 min条件下,氧化纤维中羧基和醛基含量分别为85.43μmol/g和57.32μmol/g,聚合度为154,Zeta电位为?34.72 mV。傅里叶变换红外光谱(FT-IR)表明Fenton氧化纤维成功制备,扫描电子显微镜(SEM)、X射线衍射(XRD)、热重分析(TG)表明MFC尺寸分布比较均匀,直径在200nm左右,结晶度为81.3%,热稳定性有所降低。

Preparation of Microfibrillated Cellulose through Catalyst Preloaded Fenton Oxidation

Microfibrillated cellulose(MFC) was successfully prepared from dissolving pulp by catalyst preloaded Fenton oxidation following by high-pressure homogenization.The effects of various parameters such as the hydrogen peroxide dosage,ferrous catalyst dosage,reaction temperature and time on Fenton oxidation efficiency were discussed.Accordingly,the characterizations were carried out to investigate the microstructure and chemical structure changes of the oxidized fibers,and the morphology,crystallinity and thermal stability of MFC.The results showed that the catalyst preloaded Fenton oxidation method could significantly increase the content of carboxyl and aldehyde groups in oxidized fibers,and reduce the degree of polymerization and Zeta potential,which was beneficial to increase the electrostatic repulsion between the fibers,facilitating the subsequent homogenization treatment.Under the reaction conditions of 25% pulp consistency,H2 O2 0.15 g/g,FeSO4·7 H2 O 1.5 g,pH value 3,45℃and 120 min,the contents of carboxyl group and aldehyde group in the oxidized fibers were 85.43 μmol/g and 57.32 μmol/g respectively,the degree of polymerization was 154,and the Zeta potential was-34.72 mV.The Fourier transform infrared spectroscopy(FT-IR) indicated that the Fenton oxidized fibers were successfully prepared.The characterizations by scanning electron microscope(SEM),X-ray diffractometer(XRD) and thermogravimetric analyzer(TG) showed that the obtained MFC were uniform in size of about 200 nm in diameter,the crystallinity was 81.35%,while the thermal stability was slightly reduced.