亚氯酸钠碱性氧化制备纤维素纳米纤丝的研究

Preparation of Cellulose Nanofibril by Alkaline Oxidation Process with NaClO2

关键词:  NaClO₂  氧化  高压均质  纤维素纳米纤丝  Zeta电位

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

摘要:以高温自水解处理后的漂白硫酸盐针叶木浆为原料，采用亚氯酸钠（NaClO₂）碱性氧化结合高压均质处理制备纤维素纳米纤丝（CNF）。探讨了氧化时间、NaClO₂用量、氧化温度、浆浓对氧化后浆料Zeta电位和NaClO₂消耗情况等的影响。结果表明，NaClO₂氧化后浆料的Zeta电位显著降低，适宜的氧化条件为：氧化时间6 h，NaClO₂用量8%，氧化温度95℃，浆浓10%，该氧化条件下浆料的Zeta电位为-37.6 mV，较氧化前降低了43%。将上述氧化后的浆料进行高压均质处理，得到CNF产品，对其进行了形态尺寸、黏度、Zeta电位和热失重等分析。结果表明，最优氧化条件下得到的纸浆在80 MPa下均质70次，得到尺寸分布良好的CNF产品，其直径主要分布在20～60 nm之间，长径比大于100，CNF胶体的Zeta电位为-42.3 mV，具有良好的稳定性。

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 cellulose nanofibril(CNF). Under alkaline condition, 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 consistency were optimized, the zeta potential of the oxidized pulp, and the consumption of NaClO₂ were determined. The results showed that the zeta potential of the oxidized pulp was obviously decreased, and the optimum conditions of oxidation were as follows: pulp consistency 10%, NaClO₂ dosage 8%, oxidation time 6 h, and oxidation temperature 95℃. Under that optimized conditions, the zeta potential of the oxidized pulp was -37.6 mV, with a decrease of 43% compairing to the autohydorlyzed pulp. The oxidized pulp was treated using high-pressure homogenization to obtain CNF, and the dimension, viscosity, TG as well as the zeta potential of the CNF were analyzed. The results showed that the CNF with a good size distribution was prepared when the oxidized pulp was homogenized under 80 MPa for 70 times. The diameter distribution of the CNF was mainly in the range of 20~60 nm, and its length-to-diameter ratio was over 100. The zeta potential of the CNF was as low as -42.3 mV, indicating that the CNF had a good dispersion stability in aqueous medium.