The final bleaching of eucalypt kraft pulps with hydrogen peroxide: relationship with industrial ECF bleaching history and cellulose degradation

BACKGROUND: The process of chemical pulp bleaching is based for the most part in chlorine dioxide within elemental chlorine free (ECF) technologies. The use of greener alternatives such as bleaching with hydrogen peroxide (P stage) is not widely used owing to selectivity concerns related to transition metal‐catalyzed decomposition reactions. Even at the final stage where peroxide is recognized to boost brightness and improve the brightness stability of the bleached pulp, cellulose degradation often overcomes these advantages. This paper presents the results of studies intended to optimize final peroxide bleaching performance considering two standard ECF industrial bleaching sequences: the conventional DED and the ECF‐light OQ(PO)D (stages name: D—chlorine dioxide; E—alkaline extraction; O—oxygen; Q—chelation, (PO)—hydrogen peroxide pressurized with oxygen). RESULTS: The addition of sodium diethylenetriaminepentaacetate (DTPA) was the most effective option in terms of DED pulp bleachability and selectivity with hydrogen peroxide, as well as in terms of brightness reversion. As regards the OQ(PO)D pulp, a blend of DTPA and magnesium was the most beneficial in those properties. CONCLUSIONS: The choice of the best hydrogen peroxide stabilizer, among the different tested combinations of magnesium and chelants (EDTA and DTPA) studied, in terms of pulp bleachability, bleaching selectivity and brightness reversion is dependent on the impact of the previous bleaching stages on metallic nature and content. The pulp Mg/(Fe + Cu) ratio was highlighted as a process parameter controlling cellulose degradation in peroxide bleaching. Copyright © 2010 Society of Chemical Industry     

测量纤维卡伯值的一种新方法

介绍一种利用吖啶登染色产生的荧光特性来测量纤维卡伯值的新方法，并对其测定原理、测定方法和测量中要考虑的影响因素作了具体的阐述。     

Polyoxometalate catalyzed ozonation of chemical pulps in organic solvent media

Polyoxometalate (POM) catalyzed ozonation of chemical pulps in organic solvent media was found to be particularly effective and selective environmentally benign bleaching approach providing a way for substantial increase in pulp brightness, viscosity and degree of delignification in comparison with other ozone-based bleaching techniques. A series of tested low-boiling polar aprotic and protic organic solvents showed a well-defined capacity for ozonation improvement in the presence of Keggin-type heteropolyanion [PMo₇V₅O₄₀]⁸⁻ (HPA-5). Even moderate solvent proportion of 6% (w/w) in the reaction solution caused additional gain in brightness up to 3.4% ISO with simultaneous increase in pulp viscosity up to 8.8% and lignin removal up to 18.9% after HPA-5 catalyzed ozonation (0.8% O₃; 0.5 mM HPA), as compared with the control solvent-free process. An aqueous acetone solution was found to be the preferred reaction medium in terms of pulp brightening and delignification. Under optimized conditions, the POM-catalyzed ozonation of eucalypt kraft pulp in acetone/water solution showed remarkable brightness improvement by 15.1% ISO with additional lignin removal by 39.4% and increase in intrinsic viscosity by 3% in comparison with pulp bleached in water media.     

The antioxidant capacity of red wine in relationship with its polyphenolic constituents

The “antioxidant power” of a food is an expression of its capability both to defend the human organism from the action of the free radicals and to prevent degenerative disorders deriving from persistent oxidative stress. Purpose of this study is to analyse the antioxidant capacity (measured by means of the crocin bleaching method) of several samples of Sicilian red wines and to evaluate their dependency on the vintage and on the grape variety. Finally, the correlation between the single flavonoids compounds and the antioxidant capacity has been investigated. The analyses show that the antioxidant properties of red wine appear to be unequally influenced by the vintages for the different cultivars and that the correlation between antioxidant capacity and the total phenolic contents is weak. The latter can be explained by the fact that the wine’s antioxidant properties are influenced differently by each polyphenolic molecule.     

氧漂稳定剂NCS-PB的研制及应用

NCS-PB是模拟水玻璃、102、106对H2O2的稳定作用,研制出的新型含高分子化合物的水溶性混合物,主要组成为变性聚丙烯酰胺,对H2O2有优良的稳定作用,适用于浸漂工艺及退煮漂一浴法工艺.NCS-PB稳定剂经应用证明:H2O2分解率、漂白品的白度、聚合度等指标均达到使用要求,且超过了其它常用的稳定剂,彻底根除了硅垢之弊,具有重大经济意义.     

常用表面活性剂在彩漂液中的稳定性研究

研究了10种常用表面活性剂在含氧系彩漂液中的应用,并追踪了22个月的稳定性测试。结果表明,APG(650EC)、XP-80、AEO9、15-S-9、TO-10这5种非离子表面活性剂和烷基苯磺酸、SAS这类磺酸类物质的阴离子表面活性剂和AES均具有保持彩漂液中有效氧的稳定性,而C16MES和国产APG则不能保持彩漂液中有效氧的稳定性。     

用于应力传感的双芯光纤马赫-曾德尔干涉仪

将一根单模双芯光纤(TCF)熔接在两根单模光纤(SMF)间,实验制得双芯光纤马赫-曾德尔干涉仪(MZI)型梳状滤波器。用干涉原理分析了器件的传输谱相邻峰值的波长间隔与波长、TCF长度和两纤芯间有效折射率差的关系。结果表明,在滤波器梳状传输谱中的某中心波长处,相邻峰值的波长间隔与该中心波长的平方成正比,与TCF长度和两纤芯间有效折射率差的乘积成反比。实验检测了所制器件的应力特性,结果表明在轴向微应力的作用下,器件的传输谱向短波长方向移动,且微应力敏感度为-0.64 pm/με。     

漂粉精分解温度的试验

在不同环境下进行了漂粉精分解温度的试验,结果表明:漂粉精在158℃恒温烘箱中一般12 min左右发生分解;由此可知,在外界温度约为158℃时漂粉精会分解。     

杂多酸催化氧脱木素

简要介绍了氧漂催化剂的类型，主要概述了新型氧漂催化剂杂多酸的结构、特点、催化特性、脱木素机理及其催化氧脱木素的研究现状和发展前景。     

潲水油脱色工艺的研究

研究了双氧水氧化和活性白土吸附的联合方法对潲水油中有色物质的去除效果,考察了影响氧化、吸附过程的各种因素。确定潲水油的最佳脱色条件为:加入3.6%(W/W)的双氧水,于60℃加热搅拌20 min,然后加入5%(W/W)的活性白土升温至70℃,继续加热搅拌20 min,潲水油色泽由脱色前的黑褐色变成浅黄色,透光率增加,且脱色后潲水油的臭味基本消失,可以满足皂化生产洗衣粉的要求。