过氧酸脱木素和漂白研究近况

本文综述了过氧酸的制备技术以及在纸浆脱木素和漂白中的研究近况。用作含氧漂白剂的过氧酸具有较强的木素活化作用，有希望取代ClO_2（D）而实现纸浆的TCF漂白。     

过氧酸预处理时过氧酸与木素的反应机理

综述了过氧酸溶液（过氧乙酸、过氧一硫酸、混合过氧酸和二甲基二环氧乙烷）在预处理浆料时过氧酸与本素之间反应的有关机理,阐述了过氧酸预处理提高后续氧脱木凳的选择性,改善氧脱木素效果的原因。过氧酸作为一类具有很强氧化性的无氯漂剂,随着有关技术的日益发展和完善,完全可以代替有氯漂剂从而实现氯漂白。     

烷基—过氧丁二酸的制备与应用

叙述了表面活性剂过氧酸漂白剂合成的新方法和α或β烷基一过氧丁二酸的制备,该烷基可为6～16碳原子的不饱和或饱和直链烷基,6～20碳原子的不饱和或饱和支链烷基,带有1或多个H,1～14碳原子烷基,F,Cl,NO_3,OSO_3M,SO_3M或COOM的饱和苯基团,该M为H,碱金属或铵阳离子。该合成烷基一过氧丁二酸的新方法比较经济,收率高,安全性好。该漂白合成物可用于漂白织物和其他洗涤目的。该漂白合成物还可含有过氧酸稳定剂、成型剂、填充剂和表面活性剂。     

DMD在纸浆漂白中的应用进展

综述了二甲基二环氧乙烷（DMD）的制备方法、结构特点、选择性氧化的化学特性、与木质素的相关反应机理及DMD在纸浆漂白中的作用.DMD作为一种强的亲电氧化试剂,具有良好的脱木质素能力和选择性.DMD作为漂白剂单独用于纸浆漂白,可以使纸浆达到较高的白度;DMD作为多段漂段间的活化剂,可提高后续漂白的效果.不同于传统含氯漂白的污染性,DMD的低污染和高漂白效率的特点,使其在纸浆全无氯漂白方面有着良好的应用前景.     

不饱和橡胶环氧化改性的研究进展

综述国内外常用的有机过氧酸法、过硫酸氢钾复合盐/丙酮法和过渡金属催化剂/过氧化氢法环氧化改性不饱和橡胶的研究进展,重点分析不饱和橡胶环氧化反应的机理;概述不饱和橡胶各种环氧化改性方法的优缺点;指出未来会继续重视环境友好型不饱和橡胶环氧化改性方法及高效、低廉、可再利用催化剂等的研究。     

纸浆漂白废水中可吸附有机氯化物的特性研究进展

纸浆漂白废水中含有的可吸附有机氯化物是国内外造纸工业严控的废物,是造纸环保界关注的重点。在查阅资料基础上,对目前关于纸浆漂白废水中可吸附有机氯化物的成分、分布、生成以及降解特性等方面的研究进行了述评,重点介绍了纸浆漂白废水中可吸附有机氯化物的生成及降解性能方面的研究成果,并在此基础上对今后的研究趋势进行了展望。     

漂白活化剂制备的研究

介绍了近10年来漂白活化剂制备的进展。漂白活化刑是含有氧或氮酰基团的化合物，可与强亲核过氧酸反应产生过乙酸，从而提高漂白效果。它广泛用于织物、硬质表面和餐具的洗涤。介绍了漂白活化剂烷酰氧苯甲酸可由对(间)经基苯甲酸与各类酰化剂(从脂肪酸、酰氯、酸酐中选取)反应制备。此外，还介绍了胺类、糖类等化合物与酰化剂反应合成漂白活化剂。     

含羰基β-环糊精的合成及对苯乙烯的不对称环氧化

由β-环糊精合成单-2-羟丙基-β-环糊精,再利用二氧杂环丙烷氧化成单-2-丙酮基-β-环糊精。以过氧硫酸氢钾复合盐与单-2-丙酮基-β-环糊精产生的二氧杂环丙烷作氧化剂,考察了单-2-丙酮基-β-环糊精与苯乙烯不同物质的量比、NaHCO₃用量、过氧硫酸氢钾复合盐用量、以及反应时间和温度等对苯乙烯不对称环氧化的影响。结果表明,单-2-丙酮基-β-环糊精能诱导苯乙烯的不对称环氧化;当反应时间5 h和单-2-丙酮基-β-环糊精、过氧硫酸氢钾复合盐、NaHCO₃和苯乙烯的物质的量比为2∶6∶12∶1时,ee值可达到13%。     

海外传真

过氧化氢纸浆漂白工艺凯米拉公司开及成功一项述氧化氛纸浆漂白新工乞，据说这项新工乞不使用氯化学品或臭氧，而纸浆质量达到了用二氧化氯漂白的纸聚的质量。这项经过改进的工艺可替代臭氧工艺，适用于漂白过程的脱木质素工序，该工艺是以过氧化氢或过氧化物／过酸与聚氧金属化物的混合物的活化作用为基绌，加入杂原子化合物或硅酸盐可进一步改进其活化特性。活化剂循坏至工艺过程，排出的微量废液对环境无害。采用上述工乞可特蒸煮和氧气脱木辰素工序后仍留在纸浆中的木卮素有效地和途择性地脱除，且纸浆的全光亮度可注到90。（美雯）世界…     

日本学者开发生物漂白技术

日本神户制钢所的生物研究所和九叶大学合作,用高活性木素分解菌,成功地进行了硫酸盐纸浆的漂白,从而开发出实用的生物漂白技术.据称,用木素分解菌的生物漂白技术与非氯系药剂结合,就可得到白度为85％的全漂白纸浆,并可避免氯系漂白剂漂白所造成的环境污染。新技术包括用酶素漂白、用木素分解菌的生物漂白和同非氯系     

桉木硫酸盐浆DMD漂白工艺条件的研究

使用新漂剂二甲基二环氧乙烷（Dimethyldioxirane,简称DMD）漂白桉木硫酸盐浆时,应严格控制反应的pH值为7．0~7．5;过氧硫酸盐和丙酮用量增加,二甲基二环氧乙烷的漂白能力随之增强;5％用量的DMD漂浆经碱抽提后脱木素能力与氧脱水素相当,但前者漂浆得率高,脱木素选择性好。     

Bleaching of Olive Oil by Membrane Filtration

In this study the application of membrane processes for olive oil bleaching is investigated. Olive oil is treated by adding 0.7 wt% of bleaching earth, 0.3 wt% of activated charcoal, and 5% wt% of sodium dodecyl sulfate solution (0.05 m ) and then charged into the membrane cell. Operating conditions including pressure ((2?4) × 10⁵ Pa), temperature (25–45 °C), and stirring rate (100–300 rpm) are optimized. Physico‐chemical properties of membrane bleached oil are evaluated and compared with crude and industrially bleached olive oil. Results show that the filtration conditions for the optimized point are as follows: pressure = 3.7 bar (3.7×10⁵ Pa), temperature = 36.5 °C, and stirring rate = 300 rpm. Under optimum conditions, the amounts of carotenoid and chlorophyll contents are decreased (71.3% and 40.42%, respectively). Acidic and thiobarbituric acid values reduction in membrane‐processed oil (12.42% and 14.46%, respectively) are more than the industrial one. Also, some bioactive compounds such as sterols and phenolic compounds are increased in the membrane‐filtered sample (23.13% and 57.12%, respectively). Practical Applications: Olive oil bleaching is an important step along the refining process. Pigments and minor impurities that reduce olive oil stability are removed in this step. Given the disadvantages of conventional bleaching, alternative methods are introduced. In this study, the effect of membrane filtration on olive oil color is studied. Because of the mild operating conditions, the reduction of clay percentage, as well as the increase of bioactive compounds in optimum conditions, this method has the potential to be a good alternative to conventional bleaching processes.     

高粘度、多功能过氧化脲洁牙凝胶的制备研究

制备了具有洁牙、护牙、抗菌消炎作用的高粘度、多功能过氧化脲洁牙凝胶。该凝胶无毒、无副作用 ,在口腔应用中粘度稳定 ,避免唾液溶解 ,使洁牙成分持久释放 ,提高洁牙效率。研究了过氧化脲的制备方法 ,所制备的过氧化脲质量分数大于 98%。所制备的齿科材料为粘度 30 0～ 4 5 0Pa .s,pH值 5～ 7的无色透明凝胶 ,含过氧化脲质量分数 6 %～ 2 0 % ,稀释剂 4 0 %～ 80 % ,增稠剂 4 %～ 10 % ,pH调节剂 2 %～10 %及稳定剂、抗过敏剂、护牙剂、调味剂等成分。     

Process Modelling of Combined Degumming and Bleaching in Palm Oil Refining Using Artificial Neural Network

Combined degumming and bleaching is the first stage of processing in a modern physical refining plant. In the current practice, the amount of phosphoric acid (degumming agent) and bleaching earth (bleaching agent) added during this process is usually fixed within a certain range. There is no system that can estimate the right amount of chemicals to be added in accordance with the quality of crude palm oil (CPO) used. The use of an Artificial Neural Network (ANN) for an improved operating procedure was explored in this process. A feed forward neural network was designed using a back-propagation training algorithm. The optimum network for the response factor of phosphoric acid and bleaching earth dosages prediction were selected from topologies with the smallest validation error. Comparisons of ANN predicted results with industrial practice were made. It is proven in this study that ANN can be effectively used to determine the phosphoric acid and bleaching earth dosages for the combined degumming and bleaching process. In fact, ANN gives much more precise required dosages depending on the quality of the CPO used as feedstock. Therefore, the combined degumming and bleaching process can be further optimised with savings in cost and time through the use of ANN.     

Zur Bleichung pflanzlicher Öle III: Kontinuierliche Anordnung des Bleichprozesses

Bleaching of Vegetable Oils III: Continuous Bleaching The bleaching of vegetable oils can be carried out in either a batch or a continuous way. When the continuous procedure is performed, fresh oil and adsorbent are supplied to the system, while the bleached oil (containing different concentration of colour substances) and the used adsorbent are carried off. The kinetics of the batch bleaching has been described in literature, but the data concerning the continuous bleaching are hardly available. The present study discusses particular relations concerning the continuous bleaching arrangements.     

Peroxide Bleaching Reactions Under Alkaline and Acidic Conditions

An examination of previously reported kinetic expressions describing peroxide bleaching of wood pulp under alkaline conditions reveals that the overall process can be considered as a combination of two parallel reaction routes. The first route corresponds to a reaction involving direct participation of the perhydroxyl anion in chromophore elimination. This mechanism can be identified with the classical explanation for peroxide bleaching. The second route can be associated with reactions in which chromophores are eliminated through the action of free radical intermediate species. New experimental evidence is presented to show that processes catalysed by transition metal ions can lead to enhancement of bleaching. A two stage peroxide bleaching sequence, initially under acidic conditions in the presence of chromium, followed by alkaline conditions produces an acceleration in bleaching rate, without significant additional consumption of peroxide.     

Zur Miscellableichung von Rapsölen, 1. Mitteilung: Untersuchungen zur Bleichkinetik von Bleicherden in Rapsöl-Miscellen

Miscellableaching of Rapeseed Oils I: Investigations of Bleaching Kinetics of Bleaching Earths in Rapeseed Miscella Investigations of (pre-) bleaching of rapeseed-benzine-miscella as available as result of the extraction of rapeseed have shown that the same characteristic data which are applied for screening of their effects in a process without solvent, can be used for classifying of acid-active bleaching earths according to their relative suitability for miscella bleaching. This agrees with the fact that the bleaching kinetics in miscella is described with the same law of velocity as in the phase without solvent.     

Description of a Novel Mechanism Possibly Explaining the Antiproliferative Properties of Glucocorticoids in Duchenne Muscular Dystrophy Fibroblasts Based on Glucocorticoid Receptor GR and NFAT5

Glucocorticoids are drugs of choice in Duchenne muscular dystrophy (DMD), prolonging patients’ ambulation. Their mode of action at the protein level is not completely understood. In DMD, muscle tissue is replaced by fibrotic tissue produced by fibroblasts, reducing mobility. Nuclear factor of activated T-cells 5 (NFAT5) is involved in fibroblast proliferation. By treating one DMD fibroblast cell culture and one of unaffected skeletal muscle fibroblasts with methylprednisolone (MP) or hydrocortisone (HC) for 24 h or 12 d, the antiproliferative properties of glucocorticoids could be unraveled. NFAT5 localization and expression was explored by immunocytochemistry (ICC), Western blotting (WB) and RT-qPCR. NFAT5 and glucocorticoid receptor (GR) colocalization was measured by ImageJ. GR siRNA was used, evaluating GR’s influence on NFAT5 expression during MP and HC treatment. Cell proliferation was monitored by IncuCyte ZOOM. In DMD fibroblasts, treatment with MP for 24 h induced dots (ICC) positive for NFAT5 and colocalizing with GR. After 12 d of MP or HC in DMD fibroblasts, NFAT5 expression was decreased (RT-qPCR and WB) and growth arrest was observed (Incucyte ZOOM), whereas NFAT5 expression and cell growth remained unchanged in unaffected skeletal muscle fibroblasts. This study may help understand the antiproliferative properties of glucocorticoids in DMD fibroblasts.