Analyzing the Stability of the Water-in-Diesel Fuel Emulsion

The diesel engine exhaust gas consists of many hazardous components that need to be reduced. Incorporation of water in fuel restricts the emission of such toxic gases and helps to reduce pollution. The aim of this research work is to develop a water-in-diesel fuel emulsion having maximum stability. Initially, the most suitable surfactant/blend of surfactants has been investigated, which gives the maximum stability to the Water-in-Diesel (W/D) emulsion. It is found that a blend of Span 80 and Tween 80 gives an effective result. The W/D emulsion was prepared by using a high-speed mixing homogenizer and adding a small amount of water into the diesel containing blend of Span 80 and Tween 80. The results show that 10% W/D emulsion having 5% surfactant concentration gives the most desirable emulsion stability. Beyond 10% water concentration, the properties of the W/D emulsion get lowered.     

乳状液对色谱过程的影响

运用特征线法和多流动相色谱的概念,从理论上研究了在非线性色谱过程中流动相为乳状液时其溶质浓度波的类型与特征。当流动相为乳状液时,溶质在乳状液的内相和外相之间发生分配并同时在固定相上进行吸附,此时其浓度波图像与流动相为均相时有很大不同。结合相应的算例分析并讨论了表面活性剂在乳状液内相和外相间的分配关系及其在固定相上的吸附等温线为Langmuir型时其浓度波的各种运动图像及形成机理,并与流动相为均相时的色谱过程作了比较。分析结果表明,多流动相的存在可能使简单波“陡峭化”而成为激波,或使激波溃散为简单波。     

界面膜引发的乳化燃油燃烧中的振荡反应

有关小分子醇、H。和CO等易燃气体在铂催化下的高温燃烧的温度振荡及以表面活性剂为关键组分的液膜扩散振荡已有报道"－'－．但由界面膜作用而产生的乳化燃油燃烧中的振荡反应尚无其它可操作的原始研究文献,只是在前文［'j中提及过出现该现象．为了解乳化燃油燃烧过程中界面变化及其对燃烧的作用,通过静态燃烧实验配方的调节及变换以改变燃烧界面的情况．实验发现,在乳化燃油中加入一般的食用豆油,并使之水解出长链竣酸盐,则富集在燃烧界面上的长链竣酸盐所形成的界面膜对燃烧的自阻抑作用便会产生明显的振荡反应,形成火焰温度与高…     

乙酸对阳离子型PVAc乳液粒径的影响

以醋酸乙烯酯(VAc)和甲基丙烯酰氧基乙基三甲基氯化铵为主单体,Gemini超支化双子型阳离子表面活性剂和OP-10为复合乳化剂,通过乳液聚合制得一系列阳离子型聚醋酸乙烯酯乳液(1n),考察了VAc的主要杂质乙酸对1n粒径的影响.研究结果表明,乙酸含量增多时,Gemini超支化阳离子表面活性剂的临界胶束浓度和表面张力都...     

三元复合驱碱/表面活性剂/聚合物模拟原油乳状液稳定动力学特性

基于两相分离的乳状液稳定模型,研究了三元复合驱模拟原油乳状液稳定动力学特性;通过液膜强度和油水界面张力探讨了碱/表面活性剂/聚合物对模拟原油乳状液稳定动力学特性的影响机理。 结果表明,乳状液稳定模型可以很好的评价乳状液的稳定性,并得到乳状液的稳定动力学特性;碱浓度小于900 mg/L有利于乳状液的稳定,碱浓度大于900 mg/L不利于乳状液的稳定;表面活性剂和聚合物浓度的增加使得形成的模拟原油乳状液更加稳定;模拟原油乳状液的稳定作用主要是通过碱、表面活性剂降低油水界面张力并增加油水界面膜强度,聚合物通过提高界面膜强度实现的,三者存在协同效应。     

柴油乳状液与微乳液的制备及节能效果研究

研究了用非离子表面活性剂制备含水柴油乳状液和微乳液伯条件，测定了掺水柴油在不同燃料条件下的放热量，结果表明，在供氧充分的条件下，水的掺入对燃烧热无贡献，若在大气中燃烧，掺水柴油以喷燃方式进料，一般掺水量以１０－２０％（Ｗ／Ｗ）时燃烧效率较高，若水中含有某些金属离子，掺水量达３０％，仍有较高的热效率，柴油微乳液的稳定性虽比柴油乳状液好，但只要两者的水量相同，燃烧时的放热是相同。     

Reactive Surfactant in the Emulsion Copolymerization of Methyl Methacrylate and Octyl Acrylate

The emulsion copolymerization of methyl methacrylate and octyl acrylate was studied using a reactive surfactant ammonium sulfate allyloxy nonylphenoxy poly(ethyleneoxy) (10) ether (DNS‐86), and a conventional surfactant sodium dodecylbenzene sulfonate (DBS) with a similar structure as a comparison sample. A series of latex samples have been prepared with two kinds of surfactants, and their properties have been characterized and compared. ¹H‐NMR proves that the reactive surfactant has been incorporated into the resulting copolymers. The atomic force microscopy (AFM) proves that the reactive surfactant DNS‐86 migrate to the surface of the latex film to a much less degree than the conventional surfactant DBS. Transmission electron microscopy (TEM) demonstrates that there are some differences in the particle morphologies. The stability and water‐resistance of the latex films prepared by reactive surfactant DNS‐86 are better than those prepared by the conventional surfactant DBS.     

乳化剂对聚硅氧烷乳液稳定性的影响

研究了乳化剂烷基酚聚氧乙烯醚(OP)、烷基聚氧乙烯醚和烷基季铵盐对聚硅氧烷乳液聚合的影响。采用复合乳化剂可以提高乳液稳定性。结果表明：①在以D4、N-β-氨乙基-γ-氨丙基甲基二甲氧基硅烷为原料的乳液聚合中。当非离子型乳化剂烷基聚氧乙烯醚和离子型乳化剂烷基季铵盐复合使用时,二者性能互补,产生协同效应,可使聚合物乳液具有很大的稳定性。②在实验选定的乳化剂中,非离子型烷基聚氧乙烯醚乳化剂用量为80mL(含量为0．05g／mL)、离子型烷基季铵盐乳化剂为60mL(浓度为0．05g／mL)时。其乳液的电解质稳定性、pH稳定性、冻融高温稳定性和离心稳定性等较好。     

Emulsion polymerization of methyl methacrylate in the presence of novel addition–fragmentation chain‐transfer reactive surfactant (transurf)

Reactive surfactants allow the surfactant molecules to become covalently bound to the particles and thus provide added stability to the colloid particles, longer shelf life, better shear resistance, and polymer particles that can be redispersed. This article reports for the first time the use of a novel addition–fragmentation chain‐transfer reactive surfactant (transurf) in ab initio emulsion polymerizations of methyl methacrylate at 70 °C. It was found that the rate was lowered and average particle diameter nearly doubled when the transurf was used as compared with the SDS experiments (control). In addition the molecular weight distribution was very broad but had a lower Mn than observed in the sodium dodecyl sulfate experiment. Unfortunately because of the formation of many water‐soluble oligomers, the amount of transurf incorporated could not be obtained accurately. However, it was estimated theoretically that only a very small amount of transurf would be consumed, but for an alternative method to increase the incorporation of transurf into the particles, the ratio of monomer to transurf must be kept as low as possible. The best way to achieve this would be to carry the experiments out under starved‐feed conditions. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2813–2820, 2001     

P(MMA-M12-BPMA)乳液的合成及紫外吸收性能

以甲基丙烯酸甲酯(MMA)、可聚合乳化剂马来酸酐衍生物磺酸钠(M12)和可聚合紫外线吸收剂2-羟基-4-(3-甲基丙烯酰氧基-2-羟基丙氧基)苯甲酮(BPMA)为原料,采用乳液聚合方法制备了P(MMA-M12-BP-MA)共聚物乳液。通过转化率、红外光谱、以及紫外吸收光谱测定,分别研究了M12含量对聚合反应速率的影响、所得共聚产物的结构、以及共聚物乳液和共聚物紫外吸收特性。结果表明,随M12含量增大,聚合反应速率增加;BPMA含量增大有利于提高共聚物乳液和共聚物紫外吸收性能。     

Effect of the Pyrolysis Step on the Filtration Combustion of Solid Organic Fuels

Russian Journal of Applied Chemistry - The results of filtration combustion of various types of wood and wood charcoal are compared. Data on the temperature and composition of the gas in...     

正十二烷高温机理简化及验证

由于详细化学反应机理在模拟燃烧室燃烧时,计算量极大,很难被广泛运用。为了满足工程设计要求,采用替代燃料的简化机理进行计算不失为一种行之有效的方法。本文基于误差传播的直接关系图法和敏感性分析法对正十二烷180组分1962步高温机理(温度大于1100 K)进行简化,获得40组分234步化学反应机理。在温度为1100–1650 K,压力为0.1–4 MPa条件下,采用简化机理及详细机理对不同当量比、压力下着火延迟时间进行模拟,模拟结果与实验数据吻合得较好。通过对不同压力及温度下火焰传播速度进行模拟,验证了简化机理能够正确地反映正十二烷的燃烧特性。利用C_(12)H_(26)/OH/H_2O/CO_2等重要组分随时间变化的数据,验证了简化机理能够准确描述燃烧过程反应物消耗、基团变化、生成物产生的过程,并表明该机理具有较高的模拟精度。利用该简化机理对本生灯进行数值分析,结果表明该机理能够准确地反映火焰区温度和组分浓度的变化。紧凑的正十二烷高温简化机理不仅能够正确体现其物理化学特性,而且能够用于三维数值模拟,具有较高的工程运用价值和应用前景。     

Adaption of the Mechanism of Emulsion Polymerization to New Experimental Results

Summary: New experimental investigations of the 'classical' batch ab-initio emulsion polymerization of styrene reveal the important role of monomer droplets for the whole process. Monomer droplets with a size between a few and some hundreds of nanometers, which are formed by spontaneous emulsification as soon as styrene and water are brought into contact, have a strong influence on the particle nucleation, the particle morphology, and the swelling of the particles. Experimental results confirm that micelles of low molecular weight surfactants are not a major locus of particle nucleation. Brownian dynamics simulations show that the capture of matter by the particles (monomer or radicals) strongly depends on the polymer volume fraction and the size of the captured species (primary free radicals, oligomers, single monomer molecules, or clusters).     

Formation Mechanism of Zinc Oxalate Particles in the Internal Aqueous Droplets of Emulsion Liquid Membrane

We have investigated the formation and evolution of zinc oxalate particles in internal aqueous droplets and their effects of emulsion interface properties. The formation of particles follows an aggregation-controlled mechanism that depends on the size of droplets and surfactant. The size of droplets determines the final shape of the particles by affecting the supersaturation ratio to form rod-like and sheet-like particles. The surfactant adsorbed on the particles changes the wettability, leading to the aggregation of the primary particles at the internal water-oil interface. Moreover, the adsorption can cause a higher level of impurity and defects in as-synthesized particles. This effect could be directly employed to fabricate heterojunction rectifier.     

Evaluation of Water-in-Crude-Oil Emulsion Stability Using Critical Electric Field: Effect of Emulsion Preparation Procedure and Crude Oil Properties

The critical electrical field has been used as a tool to probe water in crude emulsion stability to electrical fields in many previous studies. Given the increasing importance of this metric, this study investigates factors that are important to the reproducibility of the measurement and the effect of emulsion preparation variables on the critical electric field. It was observed that the emulsion preparation procedure has a strong effect on the measured critical electric field due to droplet size effects. Furthermore, the effect of crude oil properties on the critical electric field was investigated using emulsions from different oils but with the same average droplet diameter, where it was found that the measurement was dominated by crude oil viscosity.     

Extension of the Taylor Equation for Oil-Water-Surfactant System and Investigating the Impact of Surfactant Concentration over the Quality of Emulsion

Emulsions stand among the most important multiphase fluids, exhibiting various complicated phenomenon. To understand the process of emulsification, the Taylor equation has been extended to incorporate the parameters that depend on molecular mass of oil and their contents and the amount of surfactant added. To test the validity of the proposed equations, four well-defined short chain (n-hexane, n-heptane, n-decane, and kerosene) oils were emulsified in water and the results were compared with the experimental ones. It has been concluded that the extended Taylor equation worked well, even in the presence of surfactant. The quality of the emulsion defined and discussed in terms of size and number of droplets was best near CMC of the surfactant used. A relationship has also been derived between CMC of surfactant and its distribution coefficient, which allows the exact value of one parameter to be determined if other is known.     

Effects of Magnetic Nanofluid Fuel Combustion on the Performance and Emission Characteristics

Although the compression ignition engines are a significant source of power, their detrimental emissions create considerable problems to the environment as well as to humans. The objective of the present experimental investigation is to examine the effects of the magnetic nanofluid fuels on combustion performance characteristics and exhaust emissions. In this regard, the Fe₃O₄ nanoparticles dispersed in the diesel fuel with the nanoparticle concentrations of 0.4 and 0.8 vol% were employed for combustion in a single-cylinder, direct-injection diesel engine. After a series of experiments, it was demonstrated that the nanoparticle additives, even at very low concentrations, have considerable influence in diesel engine characteristics. Furthermore, the results indicated that the nanofluid fuel with nanoparticle concentration of 0.4 vol% shows better combustion characteristics in comparison with that of 0.8 vol%. Based on the experimental results, NO _x and SO₂ emissions dramatically reduce, while CO emissions and smoke opacity noticeably increase with increasing the dosing level of nanoparticles.     

Comparison of the Fuel Properties of Nitromethane Emulsions in Diesel and Biodiesel Assisted by Microwave Irradiation and Magnetic Stirring

Microwaves are high-frequency electromagnetic waves that assist in the formation of emulsions by enhancing the transfer of both mass and heat between the dispersed and continuous phases of the emulsion. Nitromethane has been used to improve combustion, but it is not miscible with petroleum-derived liquid fuels. In this study, the fuel properties of two-phase emulsions of nitromethane droplets dispersed in a mixture of diesel and biodiesel prepared by microwave irradiation were analyzed and compared with those of emulsions prepared by magnetic stirring. The emulsions were composed of various mass compositions of nitromethane, diesel, and biodiesel. The experimental results show that the emulsions formed by microwave irradiation had superior fuel properties, including a higher kinematic viscosity, higher flash point, lower cold filter plugging point, and less carbon residue than the emulsions prepared by magnetic stirring. Microwave irradiation is a more effective method for the preparation of more stable emulsions containing a uniform distribution of smaller dispersed droplets. In addition, the flash point, heat of combustion, cold filter plugging point, and carbon residue decreased while the kinematic viscosity increased with the increase in the weight fraction of nitromethane in the two-phase emulsions.     

The Effect of Weight Fraction of H-PDMS on the Latex Membrane and the Stability of Composite Emulsion of H-PDMS/Acrylate

High hydrogen-containing polymethylsiloxane(H-PDMS)/polyacrylate composite emulsion was synthesized by a drop-adding method for monomer emulsion. The effects of weight fraction of H-PDMS on the stability of composite emulsion, water resistance and heat-aging resistance of the latex membrane have been investigated. The TEM demonstrated that latex particles are a core-shell structure. By analyzing the spectrums of FTIR and ¹H-NMR, it can be indicated that H-PDMS had reacted with acrylate monomer resulting chemical bond formation. The core-shell structure and chemical bond play an important role to restrain phase separation of composite emulsion and enhance the stability of the emulsion. By analyzing the surface tension, apparent viscosity and morphological structure, the results showed that the stable composite emulsion system can be obtained in which the average latex particle size was smaller than 90 nm when weight fraction of H-PDMS is below 16% (based on the weight of acrylate monomer), the stable emulsion system can be obtained in which the average latex particle size becomes larger than 90 nm when the weight fraction of H-PDMS is above 20% of the acrylate monomer. The DSC demonstrated that the T_g of pure polyacrylate is 49°C, and there is only one T_g (35°C) when the weight fraction of H-PDMS is 13%, but there are two T_g (15°C and 25°C) when the weight fraction of H-PDMS is 16%. In addition, the water resistance and heat-aging resistance of composite latex membrane enhanced gradually with the increase of amount of H-PDMS.     

多重乳状液稳定性的研究

多重乳状液稳定性的研究刘沛妍，褚莹，吴子生，严忠，康万利（东北师范大学化学系，长春，１３００２４）（大庆石油学院，安达）关键词多重乳状液，示踪法，稳定性Ｗ／Ｏ型或Ｏ／Ｗ乳状液的稳定性是研究得比较成熟的课题［１］，但对Ｗ／Ｏ／Ｗ型多重（层）乳状液稳定性...