盐水杂质对胺法制碱碳化及结晶的影响

在搅拌鼓泡反应器中进行胺法制碱的碳化试验，探讨了盐水中其它物质：CaCl2,MgCl2,KCl,Na2SO4,CaCO3,MgCO3对NaCl溶液碳化的影响，其碳化能力顺序为：CaCl2>MgCl2>NaCl>KCl.考察了温度对海盐溶液与纯氯化钠溶液碳化和重碱粒度的影响。讨论了硅油消除液液两相界面气泡的可能性，从而提出了胺法制碱中必须去除Ca^2 和Mg^2 。     

结合吸附模型预测油水液滴的界面流变性质

界面活性分子在油水界面的吸附将改变其界面性质,如界面张力、界面流变性质,从而影响乳状液体系的稳定。通过吸附模型较为准确地描述活性分子在界面上的吸附行为,是定量描述油水界面性质的有效方法之一。以Span80为界面活性物质,模拟油、去离子水为实验介质,研究了低于及超过临界胶束浓度(实验中确定为0.45 mmol·L^-1)下界面张力及界面扩张模量的影响特性,表现为界面扩张模量随Span浓度的增加而先增大后减小的趋势。将描述纯扩散弛豫的Lucassen-van den Tempel模型,同Langmuir、Frumkin、reorientation和rigorous reorientation(严格重排)吸附模型相结合,用于预测含活性分子油水界面张力及扩张流变的性质;结果表明,结合严格重排吸附模型能够准确地预测油水界面张力,界面扩张模量、相角、弹性和黏性模量随浓度、频率的变化趋势。     

牛血清白蛋白和溶菌酶混合溶液的泡沫性能与其浓度的关系

生物表面活性物质的浓度对其溶液的泡沫性能有很大的影响。泡沫性能包括起泡性和泡沫稳定性。本文以初始泡沫高度和泡沫半衰期分别表征了起泡性和泡沫稳定性。首先利用Szyszkowski扩展方程和Rosen的经验模型,导出了低于临界胶束浓度(CMC)时,两种表面活性物质混合溶液的初始泡沫高度与其各自浓度的关系式;然后根据泡沫相中溶液的重力势能和表面能随气泡破裂而减小的规律,建立了低于CMC时两种表面活性物质混合溶液的泡沫半衰期与其各自浓度的关系式;最后用牛血清白蛋白(BSA)和溶菌酶(LZM)作为实验物系考察了这两种关系式的准确性。结果表明这两种关系式能准确预测BSA和LZM混合溶液的泡沫性能。在BSA和LZM混合溶液中,BSA能显著影响溶液的泡沫性能,而LZM对溶液泡沫性能的影响小。     

单乙醇胺水溶液化学吸收CO_2的研究

有机胺水溶液化学吸收CO2在工业上广泛应用,对其传质过程的微观机理进行研究十分必要。文中以对流扩散方程为基础,考虑了界面阻力对传质的影响,建立了带有化学反应的气液吸收过程液相侧非稳态传质模型,得到了传质系数表达式。利用激光全息干涉仪对不同液相主体流速下单乙醇胺(MEA)水溶液化学吸收CO2过程进行了实验研究,测定了传质达到稳态时的液相侧近界面浓度、浓度边界层厚度和传质系数。结果表明:随着液相主体流速的增加,近界面浓度和浓度边界层厚度减小,而传质系数增大;MEA在水溶液中的质量分数由0.1%增大到0.2%时,CO2吸收过程达到稳态时的近界面浓度、浓度边界层厚度及传质系数均增大。传质系数模型计算值与实验值吻合良好。     

泡沫浮选分离法的最新发展动态

泡沫分离是根据吸附的原理,向含表面活性物质的液体中鼓泡,使液体内的表面活性物质聚集在气液界面上,在液体主体上方形成泡沫层,将泡沫层和液相主体分开,就可以达到浓缩表面活性物质和净化液相主体的目的。泡沫分离是以气泡作分离介质来浓集表面活性物质的一种新型分离技术。本文注重介绍了泡沫浮选分离法的发展历史及其发展状况,另外也论述了其最新的发展动态,以及其优缺点。     

直链型非离子表面活性剂在油水界面吸附的动态Monte Carlo模拟

用动态Monte Carlo方法模拟了对称性和非对称性直链非离子表面活性剂在油水界面的吸附过程,得到了关于系统达到平衡所需要的时间、界面上吸附的表面活性剂分子数、界面层厚度、系统链节密度分布、油水界面张力等动态和静态信息,讨论了表面活性剂分子的结构和浓度对它们的影响;系统达到平衡所需要的时间与表面活性剂分子的结构和浓度有关,表面活性剂分子结构一定时,系统处于临界胶束浓度（CMC）以下时,平衡时间随浓度增加而增加;表面活性剂分子数目一定,平衡时间与表面活性剂的链长和结构有关;达到平衡以后,系统的链节密度分布关于油水分界面的对称性与表面活性剂分子的对称性有关;直链型非离子表面活性剂的表面活性主要由其结构决定,对于对称性的非离子表面活性剂,链越长表面活性越高,而对于非对称非离子表面活性剂,其对称性越高,表面活性越高;在链长一定的情况下,油水界面张力随着表面活性剂分子浓度的增加而增加,在达到一个稳定值后,不再随着浓度改变而改变.     

添加剂对乙二醇—水溶液沸腾传热的强化

以乙二醇—水溶液及加入微量添加剂 (表面活性物质 )为工质进行池式沸腾传热实验。实验结果表明 ,十二烷基硫酸钠等表面活性物质对乙二醇—水溶液的沸腾传热有明显的强化作用。在此基础上 ,分析了表面活性物质强化乙二醇—水溶液沸腾传热的原因。     

N—（3—十二烷氧—2—羟）丙基—N—二甲基甜菜碱两性表面活性剂的合成？…

脂肪醇和表氯醇反应得到相应的氯代甘油醚,以此为原料分别和二甲胺和氯乙酸钠进行胺化和季铵化,最后得到Ｎ－（３－十二烷氧－２－羟）丙基－Ｎ〈Ｎ－二甲基甜菜碱,本文了合成了方法和条件,并探讨了其表面活性。     

填料塔萃取回收醋酸废水的工艺研究

采用络合萃取方法处理工业中的低质量浓度醋酸废水,考察了三烷基胺与三正辛胺对醋酸废水的萃取效果,分析了三烷基胺、正辛醇和煤油体积分数、原料液初始质量浓度和pH对萃取效果的影响。利用填料萃取塔和反萃塔,观察混合萃取剂对醋酸废水的萃取效果。实验结果表明,在相同的体积分数下,三烷基胺萃取效果优于三正辛胺。在填料萃取塔中,使用混合萃取剂体积分数40%三烷基胺-30%正辛醇-30%煤油处理初始质量浓度为30 g/L醋酸水溶液,萃取效果较好,醋酸回收率可达95.25%。     

三烷基胺萃取丙酸的动力学特性

为研究胺类萃取剂萃取有机酸的动力学行为 ,以丙酸稀溶液为分离溶质 ,三烷基胺 ( 730 1)为萃取剂 ,正辛醇和煤油的混合物为稀释剂 ,采用恒界面池法考察了萃取剂和溶质浓度、搅拌速率、两相接触面积、温度等操作参数对丙酸萃取动力学的影响。结果表明 :730 1萃取丙酸为准一级反应萃取过程 ;且萃取发生在相界面 ,即界面反应萃取机制 ;表观活化能为 2 8.5kJ/mol,萃取速率受温度的影响不显著 ;经计算 ,在一般的萃取塔操作条件下 ,该体系的萃取过程为反应和传质过程的混合控制。     

Evaluation of surface-active agents by mechanical properties of highly filled composites

Mechanical spectroscopy is used to study the behavior under accelerated aging of surface-active additives in highly filled composites using a binder based on an hydroxyl-terminated polybutadiene. First, the mechanical properties of composites containing an amine polyester or an aziridine polyester are compared to those of a composite without any surface-active agents. It is thus confirmed that the aziridine polyester is a better surface-active agent than the amine polyester. The improvement in properties from the aziridine polyester is not affected by accelerated aging at 333°K. It was also established that composites with a mixture of both polyesters showed adequate initial mechanical properties and maintained those properties upon accelerated aging. Various hypotheses are proposed to explain the behavior of surface-active agents.     

Mass transfer with chemical reaction in liquid foam reactors

Mass transfer studies were conducted in a stable liquid foam reactor under various operating conditions to evaluate gas holdup, effective interfacial area, liquid-phase mass transfer coefficient and a modified interfacial mass transfer coefficient to include the surface-active agents employed. Gas holdup and effective interfacial area were evaluated experimentally. The interfacial mass transfer coefficient was evaluated semitheoretically, by considering the interfacial region as a separate phase and using the experimental data developed for mass transfer accompanied by a fast first-order chemical reaction. The liquid-phase mass transfer coefficient was also evaluated semitheoretically, using Danckwert's theory for the liquid phase and the experimental data on mass transfer accompanied by a slow pseudofirst-order chemical reaction. An experimental unit was set up to provide a stable flowing foam column, simulating the foam reactor. Mass transfer rates were studied for superfacial gas velocities in the range from 1.5 × 10⁻² m/s to 5 × 10⁻² m/s, giving gas residence times in the range from 20 to 55 seconds. A cationic and nonionic surface-active agent and three different wire mesh sizes, giving bubble size distributions in the range from 2.2 to 5.4 mm Sauter mean diameters, were employed. It is observed that gas holdup is insensitive to the type of surface-active agent; it is however, dependent on wire mesh size and gas velocity. The bubble diameter and, hence, the interfacial area are found to be insensitive to gas velocity in the range studied; they are, however, strong functions of wire mesh size. The liquid-phase mass transfer coefficient increases with increase in gas velocity. The surface-active agent introduces additional resistance to mass transfer in both reaction cases, this being the controlling one in the case of the fast reaction. A comparison with conventional packed bed contactors indicates the mass transfer rates to be about 8 times lower for the foam reactor, for the fast reaction case; for slow reactions, the foam reactor has mass transfer rates approximately 2-4 times higher than those for conventional packed bed contactors.     

Crystallization at Interfaces in Food Emulsions – A General Phenomenon

Monoglycerides based on saturated acyl chains, which are a dominating emulsifier type in foods, have been studied by interfacial tension measurements and crystallization behaviour. It was found that the requirement for formation of an interfacial film is that the concentration and temperature limits for crystallization in the corresponding oil has been reached. Thus, association of the emulsifier molecules into a layer with crystalline chains between oil and water cannot take place unless the limit of association of the emulsifier in oil has been reached. Crystals at the interface will expose a hydrophobic surface towards the oil and a hydrophilic surface towards water, and might therefore be termed surface-active crystals. This interfacial crystallization explains the mechanisms behind numerous presently applied emulsification processes, derived empirically, as well as other food emulsion phenomena, such as interfacial desorption of proteins by monoglycerides in the preparation of ice-cream.     

Mechanisms of grinding modification by chemical additives: organic reagents

The effects of dodecylammonium chloride on properties of quartz slurries that are relevant to grinding, such as pulp fluidity, flocculation and dispersion, and primary breakage, have been investigated in this study. These tests were conducted under chemical conditions (pH, ionic strength, additive concentration, etc.) similar to those used in wet ball milling tests. The data obtained were correlated with the grinding results. Amine was found to improve grinding, pulp fluidity, and primary breakage of quartz suspensions, especially in the alkaline pH range. These beneficial effects are attributed to the formation of highly surface-active amineaminium complexes in this pH range. In contrast to the above, amine decreased the grinding rate in the acidic pH range owing to increased flocculation of quartz fines in the presence of amine in this pH range. These results show that grinding of quartz can be improved by amine if other conditions such as pH are controlled. Also, the results indicate that the effect of chemical additives on grinding cannot be attributed to a single mechanism, but that the cumulative effect on different pulp properties has to be taken into consideration. Examination of the effect of all properties has led to a better understanding of the mechanisms responsible for the observed grinding aid effects in the present study.     

Effect of Surface-Active Substances on the Rheological Properties of Silicon Carbide Suspensions in Paraffin

In this paper, the possibility of stabilization of SiC suspensions in paraffin (hot-molding slips) was investigated from the colloid science point of view. By considering the surface properties of finely dispersed silicon carbide, surface-active agents (fatty amine and alkylsuccinimide) which are suitable for surface modification by chemical adsorption on SiC were selected. Adsorption of fatty amines and alkylsuccinimide was carried out in model experiments in chloroform. Increasing the length of the carbon–hydrogen chain caused the adsorption to decrease, and the adsorption area of one molecule in the saturated adsorption layer to increase. The stabilizing effect of surface-active agents resulted in improved flow behavior of hot-molding slips. The efficiency of surface-active agents increased with increased adsorption layer thickness. In highly concentrated SiC hot-molding slips, a combination of alkylsuccinimide and fatty amine proved to be very efficient. This synergistic effect of long- and short-chained surface-active agents is discussed in terms of an adsorption layer model.     

混合醇胺溶液吸收烟气中CO2

研究了温度、CO2含量与吸收液浓度对醇胺溶液吸收CO2性能的影响,并比较了不同复配体系对二异丙醇胺(MDEA)的活化效果。结果表明,醇胺溶液对CO2的吸收速率随反应时间的增加而降低,随吸收温度的升高而增强,以40℃为宜;吸收反应速率均随气、液相反应物含量增大而增强;混合体系对MDEA的活化效果为二乙烯二胺最好,乙醇胺最差。     

Tuning Interfacial Activity of Polymeric Resin–Surfactant/<Emphasis Type="Italic">n</Emphasis>-Alcohol Solution Interactions

Measurements of surface tension were carried out for several aqueous solutions of different amphiphilic systems. This research studied the interaction between two polymeric resins (more structure definition) (PR) and nonyl phenol ethoxylates (NP) with degrees of ethoxylation varying from 10 to 20 ethylene oxide groups. The results show that in mixtures of PR and NP₂₀EO, the adsorption on the surface was lower, with the molecules tending to remain within the liquid. On the other hand, mixtures of PR and NP₁₀EO have resulted in greater surface adsorption. The effect of the added alcohols was to tune the interfacial activity of the PR as function of the PR and alcohol concentrations. The general tendency of the surface tension curves to decrease with increasing PR/alcohol concentration in solutions was not significantly modified with the addition of alcohols; however, the surface tension values changed due to the addition of alcohols and a model is proposed to explain these changes, as they depend on both alcohol chain length and the PR/alcohol concentration. An emulsion stability test was performed on polymeric resins–surfactant systems to determine the correlation between their surface properties. Nonionic surfactants present in these mixtures are mainly responsible for the emulsion stability. It was concluded that mixtures of the less hydrophilic PR (PR_B) with NP₁₀EO have good interfacial properties, including a high interfacial concentration and a low critical micellar concentration.     

Thin film composite nanofiltration membranes fabricated from polymeric amine polyethylenimine imbedded with monomeric amine piperazine for enhanced salt separations

Thin film composite (TFC) nanofiltration membranes were fabricated by interfacial polymerization using polymeric amine polyethylenimine (PEI) and monomeric amine piperazine (PIP) as the amine reactant. Membranes with a single-ply polyamide layer were produced by reacting trimesoyl chloride (TMC) with mixed amines of PEI and PIP, and incorporation of a small amount of PIP in PEI was found to increase the permeation flux effectively while still maintaining a good solute rejection. For instance, adding 10 wt% PIP in the amine reactant solution resulted in a 6-fold increase in permeation flux, while a 91.6% MgCl₂ rejection was maintained. In addition, 2-ply polyamide membranes were also prepared by two cycles of PEI–TMC and PIP–TMC interfacial reactions separately, and they showed a higher rejection than the single-ply polyamide membrane. At a low PIP/PEI concentration ratio, the single-ply polyamide membranes formed with mixed amines of PIP and PEI tended to be more permeable than the 2-ply polyamide membranes. However, it was demonstrated that by properly controlling the PIP/PEI concentration ratio, the 2-ply polyamide membranes with both a higher permeation flux and salt rejection than conventional single-ply polyamide membranes could be produced. The resulting membranes were characterized for chemical composition, surface hydrophilicity, surface charge and morphology of the polyamide skin layer.     

Liquid–liquid extraction of copper(II)–EDTA chelated anions with microporous hollow fibers

The rates of extraction of Cu(II)–EDTA (ethylenediaminetetraacetic acid) chelated anions from aqueous solutions across microporous hollow fibers to kerosene solutions of Aliquat 336 (a quaternary amine) were measured. Experiments were performed as a function of aqueous pH, the chelated anion concentration, the organic amine concentration, and temperature. From experiments performed on the temperature dependence of extraction rate, it was shown that the resistance of interfacial chemical reaction was negligible. It was shown that the extraction rate increased with increasing concentrations of both the chelated anions and the amine. However, the aqueous pH had little effect on extraction rate under the ranges studied. The mass transfer mechanism of this extraction process was also discussed. © 2000 Society of Chemical Industry     

Preparation of dibasic acid-containing soy phospholipids by chemical and enzyme-catalyzed transesterification and evaluation of their surface-active properties

The preparation of dibasic acid-containing soy phospholipid was made by transesterification reaction with alkyl ester of diabasic acid with both lipase and alkoxide as a catalyst. The extent of incorporation of a dibasic acid varied with the molecular size of the dibasic acid. The extent of incorporation in soy phospholipids was 4–13% in the case of adipic acid and 9–20% in the case of sebacic acid. The surface-active properties of these modified soy phospholipids were examined and were found to be different from those of the original (unmodified) soy phospholipid. The interfacial properties such as critical micelle concentration (CMC), γ_CMC, surface excess concentration Γ_max, and minimum area per molecule (Å), and thermodynamic parameters such as standard free energy of micellization, were found to depend on the hydrophobic part of the dibasic acids.