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均相体系中,采用H2O2氧化降解法得到低分子量壳聚糖;以其为原料,氯磺酸-二甲基甲酰胺(DMF)为磺化试剂,在较温和的条件下制备低分子量磺化壳聚糖(S-LCTS),产物分子量较磺化壳聚糖(S-CTS)显著降低.红外光谱分析表明,所得产物在1236cm-1和808cm-1处有特征吸收,分别显示出-SO3H基团中S=O和C-O-S的伸缩振动.本文还检测了所得产物对超氧自由基(O2-·)、过氧化氢(H2O2)以及l,1-二苯代苦味酰基自由基(DPPH·)的清除效果.实验结果显示,S-LCTS对O2-·、H2O2和DPPH·的清除效果明显优于S-CTS,显示了良好的抗氧化活性. 相似文献
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不同黏均分子量壳聚糖制备及在染整中的应用 总被引:2,自引:0,他引:2
研究了壳聚糖在中性条件下用H2O2进行氧化降解的情况,讨论了反应温度和H2O2浓度对氧化降解反应的影响。结果表明,用H2O2使壳聚糖在中性条件下氧化降解是制备低分子量壳聚糖的一种简便易行的方法,以分子量为4.5万左右的壳聚糖预处理的棉织物,对活性染料染色增深效果最明显。 相似文献
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甲壳低聚糖是壳聚糖降解后的产物,其与壳聚糖相比分子量更小,水溶性更好,生物利用度更高。采用超声波协同α-淀粉酶处理壳聚糖制备甲壳低聚糖,以还原糖含量作为产品制备收得率的指标,通过正交实验优化制备工艺。结果表明,最佳工艺条件为:酶浓度1 000 U/g、酶解温度55℃、反应时间50 min、p H 5.2。在该条件下获得的降解产物还原糖浓度为2.25 mg/m L,制备效果优于单独超声波和酶解降解方法。对此方法制备的甲壳低聚糖的体外抗氧化活性进行研究,与抗坏血酸对比,其对DPPH自由基和超氧阴离子(O2-·)均有较强的清除能力。 相似文献
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本文采用H2O2氧化降解法对壳聚糖进行降解,对降解前后壳聚糖的分子量、脱乙酰度及聚集态结构进行测定和分析,并探讨壳聚糖对真丝绸抗皱性能的影响.结果表明,降解后壳聚糖的分子量明显降低,脱乙酰度提高,分子间作用力减弱,结晶度降低,热稳定性下降.壳聚糖可以明显改善真丝织物的抗皱性能,且降解后分子量较小的壳聚糖对织物的抗皱性能更佳. 相似文献
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针对染料废水色度大,光催化降解体系受限于通透性差的问题,采用化学共沉淀法制备了MgFe2O4催化剂。利用傅里叶转换红外光谱FT-IR、X射线粉末衍射仪和纳米粒度仪表征MgFe2O4的结构。通过实验考察了该催化剂在微波辐照下催化H2O2脱色活性染料的效果。在单因素实验设计基础上,结合响应面分析,研究了MgFe2O4质量浓度、H2O2体积分数、微波功率和反应时间对模拟染料废水脱色率的影响。实验结果表明,MgFe2O4质量浓度4.5 g/L,H2O2体积分数6.2 m L/L,微波功率281.58 W,反应时间7.86 min时,该催化体系可使200 mg/L活性染料废水的脱色率接近100%,且催化剂可通过磁力回收重复使用。 相似文献
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利用双氧水氧化降解壳聚糖,以2,3-环氧丙基三甲基氯化铵为改性剂,对氧化降解后的低分子量壳聚糖进行季铵化改性,得到壳聚糖季铵盐(HTCC),利用HTCC对大豆蛋白复合纤维改性后进行无盐染色,并与传统染色工艺进行对比分析。红外光谱曲线表明己经有效合成了HTCC;实验结果显示,季铵化改性后可以大大提高壳聚糖的水溶性,取代度达到90%左右;另外发现,HTCC在温度90℃、浓度8 g/L条件下浸渍处理大豆蛋白复合纤维10 min,可获得最佳的预处理效果;经HTCC改性的大豆蛋白复合纤维织物在染色中可以降低盐的用量,且无盐染色织物水洗色牢度与传统染色工艺的相当。 相似文献
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分光光度-低压离子色谱法测定Cu2+、Ni2+、Zn2+、Pb2+、Fe2+和Mn2+ 总被引:1,自引:1,他引:0
建立了分光光度-低压离子色谱法测定Cu2+、Ni2+、Zn2+、Pb2+、Fe2+和Mn2+6种重金属离子的分析方法.选用柠檬酸-草酸混合液作为洗脱体系进行梯度洗脱,将6种金属离子完全分离,柱后采用1-(2-吡啶偶氮)-2-萘酚(PAN)进行衍生反应,于波长560 nm处进行检测.6种离子的检出限分别为0.006、0.012、0.005、0.125、0.070、0.020 mg/L.该方法用于环境水样测定,结果与原子吸收法所测值基本吻合,分析结果令人满意. 相似文献
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添加助剂的过氧化氢漂白 总被引:2,自引:0,他引:2
麦草NaOHO2/NaOH两段蒸煮纸浆具有良好的可漂性,采用简单的酸处理H2O2漂白(AP)程序,仅用15%的H2O2可使漂白浆的白度达到74%~753%(ISO)。为了进一步提高麦草NaOHO2/NaOH两段蒸煮纸浆无氯漂白的效果,又进行了添加助剂的H2O2漂白试验。1试验部分漂白用浆为麦草NaOH预处理O2/NaOH蒸煮的氧碱浆,其白度为594%(ISO),卡伯值109,粘度827ml/g。漂白采用酸处理H2O2漂白(AP)程序,浆样先用H2SO4进行预处理,再进行H2O2漂白。酸处理在烧杯中进行,H2… 相似文献
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氯化钙用于高得率浆H2O2漂前预处理 总被引:2,自引:1,他引:2
研究了CaCl2用于高得率桦木浆H2O2漂前预处理的效果,并与DTPA、EDTA、H2SO4等预处理剂的预处理效果进行了比较。结果表明,CaCl,是一种优良的预处理剂。CaCl2预处理的适宜条件为:用量0.5%,pH值7,温度40℃,时间25min。 相似文献
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Yu-Jing Zhu Han-Tao Zhou Yong-Hua Hu Jian-Yang Tang Ming-Xing Su Yun-Ji Guo Qing-Xi Chen Bo Liu 《Food chemistry》2011
The inhibition kinetics of 2-phenylethanol, 2-phenylacetaldehyde and 2-phenylacetic acid on the enzyme activity of mushroom tyrosinase have been investigated. The results showed that these aromatic compounds can lead to reversible inhibition of the enzyme; furthermore, 2-phenylacetaldehyde and 2-phenylacetic acid are uncompetitive inhibitors and 2-phenylethanol is a mixed-type inhibitor. The inhibition constants have been determined and the inhibiting ability was: 2-phenylacetaldehyde > 2-phenylacetic acid > 2-phenylethanol, indicating that the functional group on the benzene ring group played an important role in the inhibition of the enzyme. In addition, 2-phenylacetic acid and 2-phenylethanol were found to have effective antibacterial activities, and 2-phenylacetic acid was more effective against Escherichia coli and Ralstonia solanacearum than 2-phenylethanol, but 2-phenylacetaldehyde lacked of antibacterial activity. 相似文献
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Cerrato JM Barrows CJ Blue LY Lezama-Pacheco JS Bargar JR Giammar DE 《Environmental science & technology》2012,46(5):2731-2737
The dissolution of UO(2) in a continuously stirred tank reactor (CSTR) in the presence of Ca(2+) and Zn(2+) was investigated under experimental conditions relevant to contaminated groundwater systems. Complementary experiments were performed to investigate the effect of adsorption and precipitation reactions on UO(2) dissolution. The experiments were performed under anoxic and oxic conditions. Zn(2+) had a much greater inhibitory effect on UO(2) dissolution than did Ca(2+). This inhibition was most substantial under oxic conditions, where the experimental rate of UO(2) dissolution was 7 times lower in the presence of Ca(2+) and 1450 times lower in the presence of Zn(2+) than in water free of divalent cations. EXAFS and solution chemistry analyses of UO(2) solids recovered from a Ca experiment suggest that a Ca-U(VI) phase precipitated. The Zn carbonate hydrozincite [Zn(5)(CO(3))(2)(OH)(6)] or a structurally similar phase precipitated on the UO(2) solids recovered from experiments performed in the presence of Zn. These precipitated Ca and Zn phases can coat the UO(2) surface, inhibiting the oxidative dissolution of UO(2). Interactions with divalent groundwater cations have implications for the longevity of UO(2) and the mobilization of U(VI) from these solids in remediated subsurface environments, waste disposal sites, and natural uranium ores. 相似文献