Abstract

Production of nanocellulosic materials from loblolly pine (Pinus taeda) kraft pulp provides an opportunity to diversify the portfolio of traditional pulp and paper industries. In this study, pinewood was first subjected to dilute acid pre-extraction with 0.5% sulfuric acid in order to fractionate the hemicellulose, followed by kraft pulping and elemental chlorine free bleaching in order to obtain up to 97% pure cellulose fractions. CNCs (cellulose nanocrystals) were prepared by hydrolyzing the bleached kraft pulp with 64% sulfuric acid at 45 °C for 30 min; the resultant unhydrolyzed solid residues were homogenized using a microfluidizer in order to produce cellulose nanofibers (CNFs). The dilute acid pre-extraction step resulted in complete hydrolysis of galactan and arabinan from pinewood, as well as in partial removal of mannan (80%) and xylan (58%). As a result of pre-extraction, the CNC yield and crystallinity improved by 44% and 11%, respectively, from the corresponding kraft pulps. CNCs produced from the pre-extracted materials also exhibited 16% reduction in particle size, but a 70% increase in sulfur content as well as 20% increase in zeta potential. Higher purity of kraft pulps resulted in higher exposure of cellulose crystalline domains to sulfuric acid thereby resulting in the observed changes. Thus, pulp purity was found to play a significant role in determining the quantity and quality of nanocellulosic materials derived from loblolly pine.

中文翻译：

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研究半纤维素预提取物对火炬松纳米纤维素的生产和表征的影响

摘要

用火炬松（taeda松）生产纳米纤维素材料牛皮纸浆为传统纸浆和造纸行业的多元化提供了机会。在这项研究中，首先将松木与0.5％的硫酸进行稀酸预萃取，以分馏半纤维素，然后进行牛皮纸制浆和无元素氯漂白，以获得高达97％的纯纤维素馏分。CNCs（纤维素纳米晶体）是通过将漂白的牛皮纸浆用64％的硫酸在45°C下水解30分钟来制备的；使用微流化器将所得的未水解固体残留物均质化，以生产纤维素纳米纤维（CNF）。稀酸的预萃取步骤导致半木聚糖和阿拉伯聚糖从松木中完全水解，以及部分去除了甘露聚糖（80％）和木聚糖（58％）。由于预提取，相应的牛皮纸浆的CNC收率和结晶度分别提高了44％和11％。由预提取的材料生产的CNCs的粒径也减小了16％，但是硫含量增加了70％，ζ电位增加了20％。牛皮纸浆的较高纯度导致纤维素晶体结构域对硫酸的较高暴露，从而导致观察到的变化。因此，发现纸浆纯度在确定源自火炬松的纳米纤维素材料的数量和质量中起着重要作用。牛皮纸浆的较高纯度导致纤维素晶体结构域对硫酸的较高暴露，从而导致观察到的变化。因此，发现纸浆纯度在确定源自火炬松的纳米纤维素材料的数量和质量中起着重要作用。牛皮纸浆的较高纯度导致纤维素晶体结构域对硫酸的较高暴露，从而导致观察到的变化。因此，发现纸浆纯度在确定源自火炬松的纳米纤维素材料的数量和质量中起着重要作用。