TEMPO-mediated oxidation of softwood thermomechanical pulp
TEMPO-mediated oxidation of softwood thermomechanical pulp
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DOI：
10.1515/hf.2009.096
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发表时间：
2009-09
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影响因子：
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通讯作者：
Yusuke Okita;Tsuguyuki Saito;A. Isogai
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文献类型：
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作者：
Yusuke Okita;Tsuguyuki Saito;A. Isogai
摘要：将软木热机械纸浆（TMP）悬浮在水中，在pH为10的条件下，用次氯酸钠和催化量的溴化钠和2,2,6,6-四甲基哌啶-1-氧自由基（TEMPO）进行氧化。当NaClO添加量为TMP的20 ~ 26 mmol g-1时，水不溶性tempo氧化的TMP组分得率约为40%。糖组成和其他分析表明，TMP中的大部分木质素和半纤维素成分被氧化去除为水溶性组分。因此，几乎纯tempo氧化纤维素也可以由TMP制备，尽管NaClO的添加水平远高于纯纤维素的tempo介导氧化。水溶性组分经核磁共振分析表明，主要化合物为葡甘露聚糖和纤维素氧化生成的多醛酸。在NaClO浓度为20 ~ 26 mmol g-1的条件下制备的tempo氧化TMP的水不溶组分羧酸盐含量约为1.2 mmol g-1，并且具有与原始TMP相同的纤维素I异型和晶体宽度。将这些tempo氧化的TMPs在水中分解得到透明且高粘性的凝胶，凝胶由单个纳米纤维组成，宽度为4-6 nm。因此，tempo氧化纤维素纳米纤维也可以由TMP制备。
Abstract A softwood thermomechanical pulp (TMP) was suspended in water and oxidized with sodium hypochlorite and catalytic amounts of sodium bromide and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) at pH 10. When the NaClO addition levels were 20–26 mmol g-1 of the TMP, the yields of water-insoluble TEMPO-oxidized TMPs fractions were approximately 40%. Sugar composition and other analyses revealed that most of the lignin and hemicellulose components in the TMP were removed as water-soluble fractions by the oxidation. Thus, almost pure TEMPO-oxidized celluloses can also be prepared from TMP, although the addition levels of NaClO are much higher than for the TEMPO-mediated oxidation of pure celluloses. The water-soluble fractions were analyzed by NMR, showing that polyuronic acids formed from glucomannan and cellulose by oxidation were the main compounds. The water-insoluble fractions of TEMPO-oxidized TMPs prepared with NaClO of 20–26 mmol g-1 had carboxylate contents of approximately 1.2 mmol g-1, and had the same cellulose I allomorph and the same crystal widths as in the original TMP. Transparent and highly viscous gels were obtained by disintegration of these TEMPO-oxidized TMPs in water, and the gels consisted of individual nanofibers 4–6 nm in width. Thus, TEMPO-oxidized cellulose nanofibers can also be prepared from TMP.