磁化后掺水乳化重油分散度的实验研究

乳化重油的分散相（水）微粒大小对重油掺水乳化燃烧技术的应用效果有很大影响,本人在过去实验的基础上,用光学反射显微镜法对磁场作用下掺水乳化重油中分散相（水）的分散度进行了测定,研究了乳化重油的分散度与磁场强度、温度以及流速之间的关系,实验结果表明：磁化后有利于乳化重油的微细化,且效果比较显著;温度的升高有利于分散相（水）的微细化,兼顾能耗和燃油的发泡、沸腾现象,以及磁化后温度的升高对分散度的影响减少,有一个合理的温度范围;磁化后分散度与流速的关系呈峰值关系,本实验中流速较佳值为8m/s;磁场强度的增大也有利于微细化,磁场强度太高或太低均不会取得太好的处理效果,在1000GS－1400GS范围内为宜。     

磁场作用下乳化重油稳定性的实验研究

燃油磁化燃烧技术是一种新的燃烧技术 ,目前以日本发展较快[1,2 ] ,其节能效果也已为实践所证实[3～ 5] 。我们知道 ,掺水乳化重油稳定性好 ,燃烧状况就稳定 ;稳定性差 ,油水在进入炉膛燃烧前就已分层 ,不但起不到“微爆”效果 ,而且严重时导致熄火。作者曾对未磁化乳化重油的粘度、稳定性和分散度进行了实验研究[6～ 8] ,丘纪华等学者[9～ 11] 对磁化技术在石油、化工、燃料等方面的作用机理及应用进行了一定的研究 ,但是重油掺水乳化后再经磁化处理后其稳定性发生怎样的变化 ,尚未见实验报道。因此 ,为了更好地发挥这一技术的节油和环保效…     

不完全相反转乳化过程分散相水滴形态发展研究

相反转乳化技术是制备高分子树脂水基分散体系的新方法[1～4].相反转指多组分体系(如油/水/乳化剂)中的连续相在一定条件下相互转化的过程,如在油/水/乳化剂体系中,其连续相由水相向油相(或从油相变为水相)的转变.在连续相转变区,体系的界面张力最低,因而分散相的尺寸最小.同理,可利用相反转技术直接将高分子树脂乳化为尺寸很小的水基微粒,即制备高分子树脂的水基分散体系.由于高分子树脂的粘弹性及相反转过程的复杂性,对高分子树脂的相反转乳化过程的机理研究较少.杨振忠[5]等通过调节高分子非离子型乳化剂浓度,可以有效地控制相反转完善程…     

乳液体系中影响分散相粒子大小及分布的因素——cmcO及cmcW的协同作用

用马尔文MastersizerMicroplus型激光粒度仪对液体石蜡及环氧树脂E-20与甲苯等有机溶剂以不同比例所形成的体系经乳化后的粒子大小及分布进行研究,结果表明,随着油溶性表面活性剂在油相中溶解性的改善,分散相的粒子大小及分布也明显得到改善.cmcO及cmcW的协同作用对获得理想的分散相粒子大小及分布起到了至关重要的作用     

分散体系形成中表面活性剂使用量的判据

通过对甲苯等有机溶剂/水/表面活性剂体系的水基化分散,利用MalvernMicroplus型激光粒度仪对乳化后的分散相粒子大小及其分布进行研究.结果表明,表面活性剂的使用量对分散结果的影响具有局限性,对于具体体系,表面活性剂的临界胶束浓度[CMC(CMC_O+CMC_W)是这种局限性的量化标志,超出CMC的表面活性剂是多余的,对最终的分散结果无作用,同时也会影响分散体系的稳定性.     

假二元微乳液体系标度律

微乳液是在表面活性物质存在下形成的油 -水混合热力学稳定体系 ,在一定条件下 ,表面活性剂双 -2 -乙基己基硫代琥珀酸钠 (AOT) -水 -正构烷烃可形成油包水型微乳液体系 ,其中分散颗粒的大小仅由水与 AOT的物质的量比 x确定[1] .这类微乳液体系有一个低临界温度 Tc,当温度高于 Tc时体系分成两相 ,两相中分散颗粒的大小相同 ,但颗粒浓度不同 ,因此 ,可看成一个假二元体系 .近年来 ,有关这类微乳液体系在临界区域与温度相关的标度律是否符合 3 D-Ising模型方面存在争论 [2～ 4 ] .本文通过精确测量 AOT-水 -正构烷烃假二元微乳液体系在…     

乳化剂分子亲水组分含量对相反转乳化过程的影响

高分子树脂水基分散体系 ,因其结构的可灵活调节性 ,在许多方面得到应用 ,又因其不含有机溶剂 ,能完全满足环境保护和生态的要求而备受关注 [1～ 3] .相反转乳化技术是制备高分子水基体系的新方法 ,它适用于制备包括加聚物和缩聚物的大多数高分子水基体系 ,大大拓宽了水基体系的范围 [4 ] .杨振忠等[5] 利用自己合成的高分子非离子型乳化剂将环氧树脂乳化成微粒尺寸小且分布窄的水基分散体系 ,对相反转机理和相反转技术进行了深入研究 .研究表明 ,乳化剂浓度和乳化温度对相反转后水基微粒尺寸和形态有重要影响 ,高乳化剂浓度和较低的乳化温…     

重油掺水乳化油稳定性的实验研究

提出了一种快速测定乳化油稳定性的实验方法－－离心分离法, 乳化油稳定性与掺水率、乳化剂量以及搅拌程度之间的关系。实验结果表明：掺水率越大,乳化油的稳定性越差,在掺水量低于１０％时稳定性较好;乳化剂量的增加和搅拌程度的增大均有利于稳定性提高。此外,还测定了两种不同乳化剂的亲水亲油平衡值（ＨＬＢ值）, ：ＨＰＥ比ＬＰＮ乳化 稳定性好;二者以一定比例混合形成的乳化剂其ＨＬＢ值在６．５￣８之间时稳定性较好     

水性聚氨酯乳化过程中相转变的研究

本文合成了单官能团小分子物质封端的脂肪族水性聚氨酯预聚物 ,通过考察预聚物加水乳化过程中粘度及电导率的变化 ,研究了其相转变行为 .实验结果表明 ,随着软段分子量升高 ,体系的相转变点后延 ;聚酯体系的相转变比聚醚体系的相转变发生得早 ;[NCO]/ [OH]值越接近 1,体系的粘度就越高 ,相转变发生所需的水含量也越高 ;羧基含量及中和度也会对分散体系的相转变产生影响 .通过选择合适的条件 ,可以实现对乳化过程的优化     

甲醇乳化柴油分散特性的研究

利用显微摄像技术及算术统计的方法表征了甲醇乳化柴油分散相-甲醇的平均粒径。研究了甲醇乳化柴油分散相（甲醇）的粒径分布随高速分散器转子转速、乳化时间、乳化剂用量和甲醇的质量分数等参数的变化。结果表明,甲醇乳化柴油分散相的平均粒径随转速、乳化剂用量的增加而减小,但随甲醇含量的增加而增大;当乳化时间为2min和转子转速为5×2800r/min,乳化剂的质量分数为5%和甲醇的质量分数为10%时,甲醇乳化柴油中分散相存在最佳的分散度,其值为16μm。
     

Solid suspension and gas dispersion in gas-solid-liquid agitated systems

The aim of the research work was to investigate the effect of superficial gas velocity and solids concentration on the critical agitator speed, gas hold-up and averaged residence time of gas bubbles in an agitated gas-solid-liquid system. Experimental studies were conducted in a vessel of the inner diameter of 0.634 m. Different high-speed impellers: Rushton and Smith turbines, A 315 and HE 3 impellers, were used for agitation. The measurements were conducted in systems with different physical parameters of the continuous phase. Liquid phases were: distilled water (coalescing system) or aqueous solutions of NaCl (non-coalescing systems). The experiments were carried out at five different values of solids concentration and gas flow rate. Experimental analysis of the conditions of gas bubbles dispersion and particles suspension in the vessel with a flat bottom and four standard baffles showed that both gas and solid phases strongly affected the critical agitation speed necessary to produce a three-phase system. On the basis of experimental studies, the critical agitator speed for all agitators working in the gas-solid-liquid systems was found. An increase of superficial gas velocity caused a significant increase of the gas hold-up in both coalescing and non-coalescing three-phase systems. The type of the impeller strongly affected the parameters considered in this work. Low values of the critical impeller speed together with the relatively short average gas bubbles residence time tR in three phase systems were characteristic for the A 315 impeller. Radial flow Rushton and Smith turbines are high-energy consuming impellers but they enable to maintain longer gas bubbles residence time and to obtain higher values of the gas hold-up in the three-phase systems. Empirical correlations were proposed for the critical agitator speed, mean specific energy dissipated and the gas hold-up prediction. Its parameters were fitted using experimental data.     

T型微通道装置制备单分散PLGA微球

利用微通道法乳化技术原理,研制了一个可拆卸T型玻璃微通道装置,以聚乙烯醇水溶液为连续相,聚(乳酸-co-羟基乙酸)(PLGA)的二氯甲烷溶液为分散相,制备了单分散的PLGA微球.考察了乳化剂用量、连续相和分散相流速以及PLGA浓度对形成的液滴平均粒径和变异系数(CV值)的影响.结果表明,增大乳化剂用量,提高连续相流速或降低分散相流速,制备得到的PLGA微球直径减小;分散相浓度在5～20 g/L之间变化时,其对微球直径的影响有限.PLGA微球表面光滑无孔,且内部是实心的.用本装置制备得到的PLGA微球,其粒径范围在30～200μm之间,CV值在15%以下,最低可至3%.该方法可使用挥发性有机溶剂作为分散相而且能避免微球制备时易堵塞等问题,可应用于药物缓控释领域中微米级单分散微球的制备.     

Fast screening of perfluorooctane sulfonate in water using vortex-assisted liquid-liquid microextraction coupled to liquid chromatography-mass spectrometry

Fast screening of trace amounts of the perfluorooctane sulfonate anion (PFOS) in water samples was performed following a simple, fast and efficient sample preparation procedure based on vortex-assisted liquid-liquid microextraction (VALLME) prior to liquid chromatography-mass spectrometry. VALLME initially uses vortex agitation, a mild emulsification procedure to disperse microvolumes of octanol, a low density extractant solvent, in the aqueous sample. Microextraction under equilibrium conditions is thus achieved within few minutes. Subsequently, centrifugation separates the two phases and restores the initial microdrop shape of the octanol acceptor phase, which can be collected and used for liquid chromatography-single quadrupole mass spectrometry analysis. Several experimental parameters were controlled and the optimum conditions found were: 50 μL of octanol as the extractant phase; 20 mL aqueous donor samples (pH=2); a 2 min vortex extraction time with the vortex agitator set at a 2500 rpm rotational speed; no ionic strength adjustment. Centrifugation for 2 min at 3500 rpm yielded separation of the two phases throughout this study. Enhanced extraction efficiencies were observed at low pH which was likely due to enhanced electrostatic interaction between the negatively PFOS molecules and the positively charged octanol/water interface. The effect of pH was reduced in the presence of sodium chloride, likely due to electrical double layer compression. The linear response range for PFOS was from 5 to 500 ng L(-1) (coefficient of determination, r(2), 0.997) and the relative standard deviation for aqueous solutions containing 10 and 500 ng L(-1) PFOS were 7.4% and 6.5%, respectively. The limit of detection was 1.6 ng L(-1) with an enrichment factor of approximately 250. Analysis of spiked tap, river and well water samples revealed that matrix did not affect extraction.     

Scale-up of high shear granulation based on agitation power

Scale-up of wet granulation in a vertical high shear mixer was conducted. Pharmaceutical excipient mixtures composed of lactose, cornstarch and micro-crystalline cellulose, and hydroxypropylecellulose as a binder were mixed together and then granulated with purified water under various operating conditions and vessel scales. Torque of agitator shaft was continuously measured and then agitation power per unit vessel volume was calculated. The agitation power per unit vessel volume showed a good correlation with physical properties of obtained granules, such as mass median diameter, strength and compressibility. This implied that the scale-up characteristics could be well analyzed by means of the agitation power per unit vessel volume. In addition, the effects of agitator tip speed and Froude number on the agitation power per unit vessel volume were investigated. The results showed that the agitation power per unit vessel volume was well characterized by the tip speed rather than the Froude number. This meant that the granule growth mainly progressed by the shear stress from the agitator blade. Dynamic characteristics of high shear granulation were also discussed here.     

溶剂挥发法制备萃取剂微胶囊

萃取剂微胶囊的制备是利用微囊化方法将萃取剂包覆起来 ,解决传统液液萃取中的两相相分散、相混合、相分离以及溶剂的损失和设备结构复杂等问题 .用简单易控制的溶剂挥发法成功制备了聚砜及聚苯乙烯材料包覆的多种萃取剂 (如磷酸三丁酯 ,2 乙基己基磷酸 ,三辛胺和Aliquat 336 )微胶囊 ,并考察了壁材和分散剂的选择对不同萃取剂进行包覆的影响 ,同时研究了搅拌速度和膜溶液组成对微胶囊的形态、萃取剂包覆量的影响 .结果表明 ,(1)用聚砜作壁材可以包覆磷酸三丁酯、2 乙基己基磷酸 ,而用聚苯乙烯可以包覆三辛胺、Aliquat336 ;(2 )对于不同的O W乳液体系 ,只有选择合适的分散剂 ,才能得到理想球形状、分散性好的微胶囊 ;(3)增大搅拌速度可以降低液滴尺度 ,从而减小微胶囊粒径 ;(4)膜溶液组成的影响则表现在两个方面 ,一是膜溶液的粘度和两相界面张力是除搅拌速度外微胶囊粒径的决定因素 ,二是膜溶液中壁材与萃取剂的比例优化时 ,才能得到萃取剂包覆量高的微胶囊 .     

Effects of vessel baffling on the drawdown of floating solids

The effects of baffling of an agitated vessel on the production of floating particles suspension are presented in this paper. Critical agitator speed, needed for particles dispersion in a liquid agitated in a vessel of the inner diameter of 0.295 m, was determined. The just drawdown agitator speeds were defined analogously to the Zwietering criterion. Specific agitation energy was calculated from the power consumption experimental data obtained by means of the strain gauge method. The experiments were carried out for twelve configurations of the baffles differing in number, length and their arrangement in the vessels. The following high-speed impellers were used: up- and downpumping six blade pitched blade turbines, Rushton turbine, and propeller. The impeller was located in the vessel in the height equal to two-thirds or one-third of the vessel diameter from the bottom of the vessel. The results were described in the form of a dimensionless equation. Presented at the 35th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 26–30 May 2008.     

固相反应合成Ba1.0Co0.7Fe0.2Nb0.1O3-δ的动力学

依据新的固相反应模型, 采用非等温热重和差示扫描量热法研究了由BaCO3和Co3O4、Fe2O3、Nb2O5粉末固相反应合成Ba1.0Co0.7Fe0.2Nb0.1O3-δ的动力学. 考察了高速机械搅拌方式混料和球磨方式混料对合成动力学的影响. 结果表明, 反应过程分为两个阶段: 第一阶段为BaCO3和Co3O4、Fe2O3、Nb2O5之间的加成反应;第二阶段为加成反应生成的BaCoO3、BaFeO3和BaNbO3三相之间固溶生成均相的Ba1.0Co0.7Fe0.2Nb0.1O3-δ, 此过程中伴随有氧的脱出. 应用修正的模型对实验结果进行了拟合, 实验数据和理论模型符合良好. 高速机械搅拌样品加成反应阶段的活化能为376.76 kJ·mol-1, 仅为球磨样品加成反应阶段活化能494.76 kJ·mol-1的3/4. 高速机械搅拌工艺促进了离子的扩散, 有利于后续反应的进行, 是更为有效、节能、环保的混料方式.