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31.
Naveen Kumar Chenna Pablo Piovano Christian Järnefelt Tapani Vuorinen 《木材化学与工艺学杂志》2016,36(5):318-328
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. 相似文献
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Colza oil bleaching through optimized acid activation of bentonite. A comparative study 总被引:1,自引:0,他引:1
The acid activation of an Algerian bentonite was investigated using a factorial 33 experiment design in order to improve the bleaching capacity in the colza oil processing. Optimized acid treatment of this bentonite gave rise to an effective bleaching earth in colza oil treatment. The 80 °C temperature value was regarded as being convenient in this study. For this purpose, the effects at 80 °C of three key parameters were investigated, namely the effects of the acid concentration in aqueous solution, the contact time and the clay to acid (S/L) ratio upon the clay effectiveness, regarded as the response function to be prone to modeling, simulation and optimization. The results showed that the acid concentration displays a stronger individual effect, as compared to the other parameters. In optimal activation conditions (acid concentration 31%, contact time 10 h and solid to liquid ratio 320 g/L), the highest bleaching capacity was found to be 99%. Comparison of the bleaching capacity from our bentonite shows that similar performances require less acid activated bentonite than any other bentonite. The acid acid-activated bentonite displayed also even higher color and chlorophyll removal than both the Tonsil and Maghnia standards, for similar bleaching earth amounts. The recommended features for the colza oil were obtained using only 1 wt.% of acid-activated bentonite, as compared to the Tonsil and Maghnia standard (1.2–1.4 and 2 wt.%, respectively). The model adequacy was also verified through additional bleaching experiment within the fixed parameters ranges, and was discussed. 相似文献
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显微观测技术可以有效地监测漂粉精生产的氯化反应进程,准确确定反应终点,从而获得较高的产率和产品质量,显微观测技术还可以用于石料活性的鉴定,简单,准确。 相似文献
36.
国产DCS在造纸行业的应用不多,尤其是在洗选漂工段更少应用,本文从项目背景、项目概况及项目实现等方面详细介绍了浙江中控的JX-300X在造纸业洗选漂工段上的应用。 相似文献
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El‐Sayed Z. El‐Ashtoukhy 《加拿大化工杂志》2010,88(1):126-132
In situ single‐stage electrochemical bleaching of kraft bagasse pulp was carried out in a cylindrical agitated vessel fitted with four graphite rod anodes and a cylindrical stainless steel screen cathode, using NaCl as an electrolyte. The effect of current density, pH, NaCl concentration, impeller rotational speed, temperature, and pulp consistency on the rate of bleaching was studied. It was found that the rate of bleaching increased with increasing current density, NaCl concentration, and temperature and decreased with increasing pH and pulp consistency. The effect of temperature was found to fit Arrhenius equation with an activation energy of 0.515 kcal/mol, which denotes a diffusion‐controlled mechanism. Energy consumption (EC) calculation showed that EC ranged from 0.225 to 3.11 kWh/kg dry pulp depending on the current density. The strength of bleached pulp was little affected by bleaching lying within an acceptable range. 相似文献
38.
在碱性条件下,用双氧水对白绒进行漂白,并在漂白过程中加入羊绒保护剂,以改善漂白后羊绒纤维的性能。通过单因素试验,重点分析了白绒漂白过程中各助剂用量对漂白效果的影响,以漂白后纤维的白度、碱溶解度等指标来评价各因素对漂白效果的影响,得出白绒漂白的最优工艺为:双氧水70%(omf),氧化稳定剂25%(omf),羊绒保护剂4%(omf),氨水1%(omf),浴比1︰20,55℃,85 min。普通白绒的白度为48.73%,碱溶解度为12.35%,单纤维强力为4.96 c N,经上述工艺漂白后的白度为66.52%,碱溶解度为13.83%。 相似文献
39.
以钛酸四正丁酯为原料,采用溶胶-微波法合成了La和Eu共掺型纳米TiO2粉体(La-Eu-TiO2),以甲基橙为模型污染物考察了掺杂量对光催化活性的影响。XRD分析表明,所得粉体均为锐钛矿相纳米TiO2,且La和Eu掺杂后纳米TiO2特征衍射峰宽化,强度降低;UV-vis吸收光谱表明,La和Eu掺杂后对光的吸收显著增强;光催化实验表明,La和Eu共掺杂能显著提高纳米TiO2的光催化活性,当La和Eu掺杂量分别为0.1%和0.25%时,纳米TiO2光催化剂具有较高的催化活性,自然光照下光催化氧化处理卷烟厂蒸叶车间废水,效果较好,废水COD去除率达到92.4%,且催化剂易沉降分离、重复使用性能稳定。 相似文献
40.
本文研究了竹子磺化化机浆(SCMP)在 H_2O_2漂白时的反应动力学,并就其发色基团的脱除机理进行了探讨。结果表明:竹子 SCMP 浆 H_2O_2漂白表现出与木材机械浆相似的反应性。竹子 SCMP 浆 H_2O_2漂白初始反应速率很快,此后渐趋平缓。提高漂白浓度,增加药品用量有利于浆中发色基团的脱除。确立竹子 SCMP 浆H_2O_2漂白动力学方程为:—dC_R/dt=k[H_2O_2]~(0.89)[OH]~(0.18)C_R~(5.25) 相似文献