亚氯酸钠碱性氧化制备微纤化纤维素的研究

Preparation of Microfibrillated Cellulose by an Alkaline Oxidation Process Using NaClO2

关键词:  亚氯酸钠  氧化  高压均质  微纤化纤维素  Zeta电位

Key Words:NaClO₂  oxidation  high-pressure homogenization  microfibrillated cellulose  zeta potential

摘要:以高温自水解处理后的漂白针叶木硫酸盐浆为原料,研究并开发了亚氯酸钠(NaClO₂)碱性氧化法结合高压均质制备微纤化纤维素(MFC)的工艺。探讨了氧化反应中氧化时间、NaClO₂用量、温度、浆浓对氧化后浆Zeta电位和NaClO₂消耗情况等的影响。结果表明：NaClO₂氧化后浆的Zeta电位降低,适宜的氧化条件为：时间6 h,NaClO₂用量8%,温度95 ℃,浆浓10%,该氧化条件下浆的Zeta电位为-37.6 mV。对高压均质后得到的MFC进行了形态尺寸、粘度、Zeta电位的表征和热失重分析,结果表明：最优条件下制备得到的MFC直径主要分布在20~60 nm,长径比大于100,MFC胶体的Zeta电位为-42.3 mV,稳定性好,MFC的热稳定性与自水解浆相近。

Abstract:In the present work, a combined method involving oxidation and high-pressure homogenization was used to treat the autohydrolyzed BKP (bleached softwood kraft pulp) for preparing microfibrillated cellulose (MFC). Under alkaline condition, the Sodium Chlorite (NaClO₂) was used as an oxidant to decrease the zeta potential and the DP of the pulp. The oxidation time, temperature, NaClO₂ dosage, as well as the pulp concentration were optimized, the zeta potential of the oxidized pulp, and the consumption of NaClO₂ were determined. The results showed that the optimum conditions of oxidation were as follows: pulp concentration 10%, NaClO₂ dosage 8%, oxidation time 6 h, and oxidation temperature 95 °C, where the zeta potential of the oxidized pulp came up to -37.6 mV under that conditions. After high-pressure homogenization, the obtained MFC was characterized. The SEM analysis showed that the diameter distribution of the MFC was mainly in the range of 20~60 nm, and its length-to-diameter ratio was over 100. The zeta potential of the MFC was as low as -42.3 mV, demonstrating that the MFC had a good dispersion stability in aqueous medium. In addition, the TGA analysis indicated that the thermal stability of the MFC was similar to the autohydrolyzed pulp.