Organochlorine Formation in Tertiary Amine Catalyzed Pulp Bleaching

An oxygen delignified eucalyptus kraft pulp was bleached by applying a catalytic amount of a tertiary amine, 1,4-diazabicyclo[2,2,2]octane, and hypochlorous acid at varying pH, temperature, and time. The bleaching filtrate was analyzed for chloroform and AOX and the pulp for residual lignin, hexenuronic acid, and OX. In comparison with chlorine dioxide bleaching, the novel catalytic bleaching (pH < 6) generated only traces of chloroform and low contents of AOX and OX. Separate catalytic oxidations of authentic hexenuronic acid showed that it was a major precursor of chloroform. The results demonstrate a practical way to reduce organochlorine formation in pulp bleaching and provide new understanding on the reaction pathways that yield chloroform.     

ECF漂白过程中AOX减量技术研究进展

对纸浆漂白过程中可吸附有机卤素(AOX)减量技术的研究背景与国内外研究现状进行了论述;并通过调查ECF漂白过程中AOX减量技术的研究进展,对AOX相关减量技术做出如下概括：①优化工艺;通过调整漂白工序减少含氯漂剂的用量,从而减少AOX的生成量。②添加化学助剂;通过添加H2O2或添加含硫基、氮基等助剂抑制AOX产生。③漂前预处理;纸浆漂白之前采用热水预抽提、酸碱预处理以及生物酶预处理等方法处理纸浆,减少纸浆中的木素和半纤维素含量,从而降低AOX生成量。     

我国制浆造纸AOX的来源分析及其减量化建议

使用AOX分析仪分析了若干纸张、纸浆、制浆原料和相关化学品AOX的含量,初步了解了制浆造纸AOX的来源并提出了几点AOX减量化建议。结果表明,收集到的纸张、纸浆、化学品、原料等都含有AOX。制浆造纸AOX的来源主要有原料本身的农药残留、水源或者化学品以及含氯漂白剂的使用。可以采用源头控制、清洁生产技术以及制定相关产品标准来减少我国制浆造纸AOX的产生量。     

木聚糖酶预处理降低漂白废水中的AOX

研究了木聚糖酶预处理对后续漂白废水中AOX含量的影响.研究表明,木聚糖酶预处理降低了纸浆中的木素含量,提高了后续漂白中纸浆的可漂性,后续漂白中在不影响纸浆白度的情况下,降低漂剂用量,减少漂后废水中AOX的含量.     

Analysis of methanol–ethanol mixtures from falsified beverages using a dual biosensors amperometric system based on alcohol dehydrogenase and alcohol oxidase

A portable bienzymatic analytical system was developed for the chronoamperometric analysis of methanol–ethanol mixtures. The system consists of two biosensors, one based on alcohol dehydrogenase (ADH) that responds only to the ethanol and the second one based on alcohol oxidase (AOX) that responds to both methanol and ethanol. The transducers were screen-printed electrodes (SPEs) modified with mediators: Meldola blue for ADH and Co-phthalocyanine for AOX. The calibration graph of the ADH biosensor is linear between 0.3 and 8 mmol/L ethanol. The AOX biosensor is able to quantify both analytes in mixtures that contain methanol between 3 and 70 mmol/L and ethanol ranging from 15 to 110 mmol/L. Interferences due to non-specific oxidations from common oxidizable compounds like gallic acid and ascorbic acid were smaller in the case of transducer based on Meldola blue. The analytical system was successfully tested on real samples: non-alcoholised beer (NAB) spiked with ethanol or methanol and a falsified rose wine (FRW).     

竹浆木聚糖酶预处理对常规CEH三段漂的影响

进行了竹浆木聚糖酶预处理对常规CEH三段漂影响的研究.实验结果表明:在总用氯量均为8.5%时,用木聚糖酶预处理的硫酸盐竹浆的白度增加了1.99%ISO;在用氯量减少了11.76%的条件下,酶预处理竹浆能够达到普通CEH三段漂的白度,同时,纸浆的裂断长、撕裂度和耐折度分别提高了7%、11%和32%;此外,用木聚糖酶预处理后再漂白工艺可有效降低废水污染负荷.     

Influence of pH on recombinant human growth hormone production by Pichia pastoris

BACKGROUND: Effect of pH on recombinant human growth hormone (rhGH) production by Pichia pastoris hGH‐Mut⁺ was investigated at pH = 4.2, 5.0, 5.5, and 6.0. RESULTS: The highest cell concentration was obtained at pH = 6.0 with 53 g L^?1, while the highest rhGH concentration was attained at pH = 5.0 as 0.27 g L^?1. Total protease secretion increased with increase in pH and with the cultivation time. Oxygen uptake rate increased with increasing pH up to pH = 6.0, having the maximum value, 37 mmol m^?3 s^?1, at pH = 5.5. K_La values were similar at all the conditions, having a maximum value of 0.14 s^?1 at pH = 5.0. Taking the final rhGH concentration into account, the most favourable pH was 5.0; where AOX1 expression level showed a similar trend to AOX activity profiles, having the highest value of 9.4 × 10¹⁰ copy mg^?1 CDW at t = 15 h; in parallel to AOX1 expression profile, hGH expression level increased until t = 15 h, with the highest value of 4.0 × 10¹⁰ copy mg^?1 CDW, where a sharp increase in rhGH concentration was obtained. The expression levels of pep4, prb1 and prc1 genes, responsible from the production of proteinase A, proteinase B and, carboxypeptidase Y, were parallel to each other. CONCLUSION: Since it was shown that pH is a crucial operating parameter in fermentation processes using P. pastoris, keeping pH constant at its determined optimum value, pH = 5.0, during the bioprocess is vital in terms of recombinant protein production. Copyright © 2010 Society of Chemical Industry     

无污染漂白--造纸工业可持续发展的要求

分析了造纸业在可持续发展中的重要地位，并从可持续发展角度论述了纸浆无污染漂白的重要性和必要性，指出无污染漂白是解决制浆工业面临的化工药品浪费大、污染严重等问题的有效途径，并提出了发展无污染漂白技术的对策。     

从OHMP漂白的工业化应用谈常规含氯元素多段漂的改造

对常规的含氟元素多段漂工艺,如CEH三段漂和CEHH/CEHP四段漂,进行OHMP清洁生产技术改造,是降低废水负荷和提高质量的较佳选择.本文主要介绍了这一改造的三个关键问题:(1)氧脱木素段数的选择和位置的确定;(2)过氧化氢漂白方法的选择;(3)过程工艺设备及管道材质的选用.     

纸浆漂白废水AOX含量的检测技术

纸浆漂白废水中AOX含量的测定分析方法除了两个国家标准外,还有仪器检测和一些简单分析方法.在分析中会有各种影响因素,采取正确及时的措施可以使AOX的检测既迅速又准确.