如何准确测定化学水中的游离二氧化碳

游离二氧化碳的含量是化学水装置的一项重要工艺参数,如何选择适当的分析方法准确测定游离二氧化碳尤为重要。测定方法有直接法和固定发两种,通过实验决定选用"固定法"测定化学水中游离二氧化碳含量,此方法灵敏度较高,滴定终点颜色易于判断,适于现场控制分析。     

普通烘箱法快速测定粒状重钙游离水含量

化工行业标准 HG2 2 2 2 91规定粒状重钙游离水分含量是采用真空烘箱在一定真空度和温度下 ,以失重来测定。此法对设备有特殊要求 ,耗时在 2 .5 h以上 ,不能满足生产控制的要求。采用普通烘箱在不同温度、不同烘干时间下对粒状重钙的游离水含量进行了测定 ,并将测定结果与真空烘箱法所测结果进行对比 ,摸索出合适的测定条件。实验结果表明 ,采用普通烘箱快速测定重钙中游离水含量的方法是可行的 ,具有测定条件简单、耗时较短的特点 ,其准确度可满足生产中控分析的要求。1　实验部分1·1　主要仪器ZK 82 A型真空干燥箱 ;2 X 2型旋片式真空…     

液体稳定剂中游离苯酚的测定

提出了一种测定液体稳定剂中的游离苯酚含量的化学分析方法。其原理基于苯酚能与溴定量反应。具体的步骤是,向液体稳定剂中加入定量的溴,用定量的碘化钾与溴化反应后剩余的溴反应,再用Na2S3O3标准溶液滴定反应生成的碘。根据Na2S3O3标准溶液用量,可以计算出液体稳定剂中游离苯酚的含量。     

电子工业用气体等十项标准通过审查

<正> 由化工部西南化工研究院主持,1991年底在蓉召开了电子工业用气体等气体标准审查会。会议审议通过了电子工业用气体氧、电子工业用气体氧化亚氮、电子工业用气体高纯氨、电子工业用气体三氟化硼、电子工业用气体氯化氢、工业液体二氧化碳、二氧化碳含量的测定化学吸附法、氧气中微量氩、氮、氪的测空气相色谱法、高纯氧和气体中总烃的测定     

低含量碳酸盐的測定

在低含量碳酸盐的测定方面,美国商业部标准局发展了一种简单快速的气体层析操作法。这种方法,用酸使二氧化碳逸出,一般适用于测定固体或液体的碳酸盐含量方面。试验极限是百万分之0.2(0.2ppm),而误差小于1%。按标准的重量法或容量法的操作技术(维持样品合理大小)。百万分之10(10ppm)以下的碳酸盐含     

工业三氯化磷中游离磷分析方法的改进

以无水乙醇替代乳化剂，使析出的银均匀分散在苯－ 乙醇－ 水体系中，在确定波长下比色测定游离磷的含量。该方法所用试剂易得，空白值较小，更利于测定低含量游离磷。     

自动电位滴定仪测定循环液中碱度

目的:本着提高工作效率,建立了一种操作简单、准确测定循环液中碱度(KHCO3)的自动电位滴定法。方法:5 m L样品中加入50 m L无二氧化碳水,使用0.5059 mol/L盐酸标准溶液进行自动电位滴定,当p H=4.2到达滴定终点,根据消耗盐酸标准溶液体积测定循环液中KHCO3的含量。结论:与用于循环液中KHCO3含量测定的手动滴定比较,自动电位滴定法具有样品用量少、仪器操作简单、终点判断准确,灵敏度高、测量数据准确,适合硫磺回收循环液中KHCO3含量的检测。     

工业三氯化磷中游离磷分析方法的改进

以无水乙醇替代乳化剂，使析出的银均匀分散在苯－乙醇－水体系中，在确定波长比色测定游离磷的含量，该方法所用试剂易得，空白值较小，更利于测定低含量游离磷。     

烷基磷酸酯钾盐中游离十二醇含量测定

本文探讨了十二烷基磷酸酯钾盐中游离醇的提取方法，并对所提取的游离醇进行了衍生化处理，利用气相色谱法进行含量测定。本方法操作简单、快速，适用于工业生产中的控制及分析。     

环保型脲醛树脂粘合剂合成的研究

脲醛树脂是广泛用于木材工业中一种重要的胶粘剂。对降低脲醛树脂粘合剂中游离甲醛含量的措施以及改性方法进行了探讨,并在大量的实验基础上摸索出了一套简单实用的合成工艺,根据此合成方法生产的产品具有粘度好、反应条件易控制、甲醛含量低和成本低等优点,树脂的甲醛含量达到国家室内板用粘合剂游离甲醛含量标准(GB18 587-2001)。     

Schneiden und Bohren mit flüssigem Kohlendioxid

Water jet cutting is used for cutting various materials for decades. However, due to the disadvantages of this method not all materials can be processed. Many disadvantages can be avoided if CO₂ is used instead of water. Carbon dioxide evaporates after processing and allows a dry, residue‐free cutting process. A method for jet cutting with liquid carbon dioxide is presented and the first results of cutting tests on various materials are shown.     

二段式吸收塔强化水洗技术提纯沼气过程

压力水洗技术已成为提纯沼气的关键技术之一。采用填料吸收塔进行CO₂脱除实验研究,考察了液气比、吸收压力、吸收温度、CO₂初始含量、填料层高度对CO₂脱除率的影响,以及液气比、沼气流量对总体积吸收系数的影响,并运用填料塔与喷雾塔结合的二段式吸收塔进行压力水洗提纯沼气的过程强化实验。实验结果表明,吸收压力和液气比的增大、吸收温度的降低、填料层高度的增加有利于CO₂的脱除,体积总吸收系数随着液气比及沼气流量的增加而增大。二段式吸收塔能够提高CO₂吸收效果,当沼气处理量为10 L·min^-1,填料层高度为100 cm,CO₂含量小于3%时,与填料塔相比二段式吸收塔可以减少约12%的吸收液用量,并且采用110 cm填料的二段式吸收塔获得最佳的提纯效果,CO₂脱除率达到97.4%。     

Mass transfer from single gas bubble — a comparative study on experimental methods

A comparative study on the experimental techniques which have been used for the study of mass transfer from single gas bubble was made. The instantaneous mass transfer rates from a single carbon dioxide bubble rising through quiescent liquid medium (water) were measured using two different methods. For the first method, two movie cameras were placed on a moving platform along perpendicular directions and were used to record the position and size change of the bubble. The second method measured the mass transfer rates by recording the pressure changes in the free space at top of the bubble column, which was caused by the change of bubble size. The instantaneous mass transfer coefficients determined by either method exhibited wide scattering which is typical of work of this kind. Discussions are given on the relative merits of these two methods.     

尿素循环水水质异常原因分析

循环水系统有工艺物料漏入,是导致水质异常的直接原因,塔西南石化厂尿素循环水碱度异常,导致加酸量、排污量和补水量剧增,通过分析判断水中有大量的HCO3-存在,找出一种快速定性测定水中游离二氧化碳的方法并在现场灵活使用,可在第一时间找出内漏的CO2冷却器,将泄漏造成的损失降到最低。     

Characterization of Products Consisting of Synthetic,Amorphous Silica and Water with Different Moistures by Means of NMR

Mixtures of liquid and powder have usually totally different structures dependent on the moisture content. They vary from dry powders with small amounts of liquid to suspensions with a low solid concentration. For all moisture contents the binding mechanisms between the solid particles and the molecules of the liquid play an important role. In order to study these interactions, various products composed of synthetic, amorphous precipitated silica and water were produced using a special spraying technology with supercritical carbon dioxide. Thus, it is possible to produce disperse solid/fluid systems with high homogeneity. All samples were studied by means of nuclear magnetic resonance (NMR) which allows to distinguish between different types of water with regard to their mobility. The aim of this study is to develop a method for the characterization of solid/liquid systems in terms of their loading capacity of the liquid.     

Desorption of carbon dioxide from supersaturated water in an agitated vessel

The rates of desorption of carbon dioxide from supersaturated water solutions into pure carbon dioxide or nitrogen gas stream were measured at 15,25, and 35°C in a baffled agitated vessel with a flat gas-liquid interface operated in a continuous manner. The volumetric liquid-phase mass transfer coefficients for the bubbles generated in the agitated liquid and the enhancement factors of the volumetric liquid-phase mass transfer coefficient for the free liquid surface due to the bubbling were calculated from the measured desorption rates and correlated as functions of the relative supersaturation of the solution and the liquid-phase Reynolds number.     

Intensified biogas purification in a stirred tank

The present study aims at intensifying the absorption of carbon dioxide in aqueous phases. For this purpose, a second immiscible liquid phase is used to improve the mass transfer of carbon dioxide in water. Absorption measurements are carried out in a stirred cell by online infrared monitoring of the output carbon dioxide concentration. As dispersed phase, 1-octanol shows an improvement in mass transfer whereas colza oil retards it. Toluene has no significant effect in the range of concentrations investigated. Mass transfer coefficients are determined using a chemical method. Nevertheless, the variety of behaviors could not be explained simply by solubility or variation of mass transfer coefficients. In order to understand the complex gas–liquid–liquid interactions and deduce the mass transfer mechanism between these three phases, surface and interface tension measurements and direct observation of bubbles and droplets are also carried out.     

Viscosity measurements on saturated gas-expanded liquid systems—Ethanol and carbon dioxide

A recently developed method of falling-weight viscometry was employed to determine the experimental viscosities of the gas-expanded liquid system of ethanol and carbon dioxide at saturation. By adding carbon dioxide into an isochoric system containing metered amounts of ethanol, carbon dioxide concentrations within the gas-expanded liquid system were systematically varied between 0.15 and 0.80 mole fraction in 0.05 increments at constant system temperatures of 25, 30, 35 and 40 °C. Similar to the gas-expanded liquid system of methanol and carbon dioxide, an increase in carbon dioxide concentration in the liquid phase, liquid volume expansion, liquid density and system pressure resulted in a decrease in liquid phase viscosity. The significance of system temperature however, is more apparent with the gas-expanded liquid system of ethanol and carbon dioxide when compared to the gas-expanded liquid system of methanol and carbon dioxide. At equal compositions but varying system temperatures, not only is the viscosity of the ethanol and carbon dioxide system affected to a greater extent, the point at which viscosity reduction is insignificant with an increase in carbon dioxide composition occurs earlier with increasing system temperatures. The estimation of liquid phase viscosities of gas-expanded liquid systems is therefore difficult without experimental data.     

Hydrophobic recovery of repeatedly plasma-treated silicone rubber. Part 2. A comparison of the hydrophobic recovery in air,water, or liquid nitrogen

Surfaces of medical grade silicone rubber (Q7-4750, Dow Corning) were modified by repeated (six times) RF plasma treatments using various discharge gases: oxygen, argon, carbon dioxide, and ammonia. The treated samples were stored for a period of 3 months in ambient air, water, or liquid nitrogen. Subsequently, the temporal behavior of the effects of the plasma treatment on the physicochemical surface properties of the silicone rubber was investigated using water contact angle measurements and X-ray photoelectron spectroscopy (XPS). Hydrophobic recovery during 3 months storage in ambient air was considerable and nearly complete for all four plasmas used. Hydrophobic recovery was almost completely suppressed during storage in liquid nitrogen, and only a minor increase of around 10° in advancing water contact angle was observed for all four plasma treatments. Also during storage of treated samples in water, hydrophobic recovery was minimal and initiated again by returning the treated samples to ambient air. XPS analyses showed that argon, carbon dioxide, and ammonia plasma-treated silicone rubber all had increased carbon percentages at the expense of oxygen and silicon after storage in water, or in liquid nitrogen, compared with after storage in ambient air. Interestingly, the carbon content of oxygen plasma-treated silicone rubber decreased during storage in water, or in liquid nitrogen, compared with storage in ambient air, while its oxygen and silicon percentages increased.     

丙烯杂质对聚合的影响及消除措施

在液相本体法生产聚丙烯工艺中,原料丙烯的质量直接影响到聚合反应,文章探讨了丙烯中的水、氧、烃类、一氧化碳、二氧化碳、硫、砷等杂质对丙烯聚合反应的影响,同时讨论了去除丙烯杂质的方法和工艺调整等措施。