司班表面活性剂对氢氧化铝表面改性的研究

对司班表面活性剂湿法改性氢氧化铝的工艺条件进行了探讨,并利用接触角测试、粒径分析、红外光谱（IR）及热重-差示扫描量热（TG-DSC）等测试表征手段,对氢氧化铝的改性效果进行了分析。结果表明,改性剂用量、改性温度及时间等工艺条件对氢氧化铝的改性效果有显著影响,且不同司班表面活性剂对应的最佳工艺条件也有差别,其中以S-60作为改性剂,在用量为0.03（与氢氧化铝的质量比）,温度为85 ℃时,经60 min改性得到的氢氧化铝效果最好。通过改性,氢氧化铝的粒径分布变得更加均匀,颗粒表面的润湿性由亲水转变为亲油。司班表面活性剂主要通过物理吸附作用实现对氢氧化铝的改性,因此氢氧化铝的化学结构没有发生变化,热稳定性也未受到明显影响。     

Binary coalescence of air bubbles in viscous liquids in presence of non‐ionic surfactant

Coalescence of air bubbles is important in gas–liquid reactors and food processing operations. Bubbles can be stabilized by using non‐ionic surfactants. Binary coalescence of air bubbles in ethylene glycol and aqueous glycerol solutions were studied in this work in presence of Span 80. A novel set‐up was developed to study long coalescence times. Coalescence time was observed to follow broad stochastic distributions in all systems. The distributions were fitted with a stochastic model developed earlier. The surface tension of ethylene glycol and glycerol solutions was measured at various concentrations of Span 80. These data were fitted using a surface equation of state derived from the Langmuir isotherm. The effect of surfactant concentration on coalescence time was explained in terms of the surface excess of the surfactant and the repulsive force generated at the air–liquid interface. The results from this work illustrate the stochastic nature of bubble coalescence in viscous liquids. This work also demonstrates how non‐ionic surfactants can stabilize bubbles in such liquids.     

Adsorption of nonionic surfactants at fluid-fluid interfaces: Importance in the coalescence of bubbles and drops

Major industrial applications of surfactants are related to the stability of emulsions and foams, which is directly dependent on the rate of coalescence of drops and bubbles. Surfactant molecules adsorb at the liquid-liquid and gas-liquid interfaces and prevent the drops and bubbles from coalescing with one another. Therefore, it is important to correlate the adsorption of surfactant with the time required for coalescence. In this work, we have studied the adsorption of three nonionic surfactants, Tween 20, Triton X-100 and Span 80 at air-water and water-toluene interfaces. The variation of surface and interfacial tension with the concentration of surfactant was studied and the data were fitted using a surface equation of state derived from the Langmuir adsorption isotherm. We have studied binary coalescence of water drops in toluene in presence of these three surfactants. Coalescence of air bubbles at flat air-water interface was studied in presence of the water-soluble surfactants, Tween 20 and Triton X-100. A stochastic model for coalescence was used to fit the coalescence time distributions. The significance of the model parameters was discussed.     

表面活性剂对水过冷池沸腾特性影响实验研究

以Tween20、Span20及两者复配物为表面活性剂,实验研究了其对水过冷池沸腾传热特性影响。基于实验结果与表面张力、接触角、临界胶束浓度等基础物性分析发现,单一表面活性剂对沸腾传热的影响由其添加种类、浓度及热通量共同决定。一方面,不同于饱和沸腾情形,过冷状态下Tween20能够有效降低沸腾起始点温度与壁面过热度,但其沸腾强化效果在高热通量下减弱;另一方面,Span20只在低浓度下表现出强化效果,其浓度增大将引起壁面过热度大幅攀升。此外,尽管Tween20与Span20都具有强化沸腾传热的潜力,但两者复配表面活性剂在实验研究浓度范围内均恶化了沸腾传热过程。研究结果可为传热强化复合工质过冷池沸腾传热特性分析提供基础依据,并为其配制提供指导。     

Synthesis of spherical zirconia by reverse emulsion precipitation

Spherical ZrO₂ microparticles were prepared in a three-phase reactor by mixing two water-in-oil emulsions with normal heptane as oil phase and aqueous solutions of zirconium oxyacetate and ammonia as water phases, respectively. The principal factors that influenced the stability of emulsion were investigated, including the surfactant type, the volume of w/o, and the concentration of zirconium ion. In this work, four anion surfactants were tested, including Span 85, Arlacel 83, Span 80 and Span 40. The most stable reverse emulsions were obtained with the surfactant Span 40. When w/o volume ratio was kept 1/100 using Span 40 or Span 80 as a surfactant, the ZrO₂ microparticles with spherical morphology were successfully prepared in the reverse emulsions at various Zr⁴⁺ concentrations (from 0.5 M to 3 M). The particle sizes of ZrO₂ are smaller for Span 40 as compared with Span 80 on the same Zr⁴⁺ concentrations. The crystalline phase of the ZrO₂ powders after calcination at 750 °C for 2 h was tetragonal.     

用聚合型乳化剂制备反相乳液的研究

以丙烯酸钠水溶液为水相,煤油为油相,Span80甲基丙烯酸酯(Span80 MA)聚合型乳化剂、Span80和Twen80为复配乳化剂,制备反相乳液。计算聚合型乳化剂(Span80MA)的HLB值,考察了乳化剂浓度、水相体积分数φ及单体浓度对乳液类型及稳定性的影响规律。结果显示:HLB(Span80MA)=4.0;形成稳定的反相乳液理想条件为:Span80MA∶Span80∶Twen80=0.7∶0.5∶0.2;乳化剂浓度为7%;φ=50%;单体浓度为2.0～3.0 mol/L。     

AM-DMC反相乳液共聚合研究

以白油为连续相，Span、Tween、OP为乳化剂，进行了丙烯酰胺—甲基丙烯酰氧乙基三甲基氯化铵的反相乳液共聚合反应。考察了乳化剂种类及用量、引发剂种类及用量、油水比、单体质量分数等因素对所得产物分子量的影响。     

氯化专用聚氯乙烯树脂颗粒特性的研究——非离子型表面活性剂和链转移剂的影响

水相悬浮法生产氯化聚氯乙烯(CPVC)时,氯化速度和氯化均匀性取决于Cl2在聚氯乙烯(PVC)颗粒中的扩散程度,因而需要有能满足氯化要求的PVC专用树脂。采用以聚乙烯醇(PVA)和羟丙基甲基纤维素(HPMC)为主的复合分散剂,考察Span系列非离子表面活性剂、链转移剂等对PVC颗粒特性的影响。实验结果表明,表面活性剂的加入使PVC树脂增塑剂吸收率、平均粒径和比表面积增大,粒径分布变窄,而表观密度下降;随着链转移剂的加入,PVC树脂增塑剂吸收率、平均粒径和表观密度都增加。     

柴油微乳液稳定性的研究

利用非离子表面活性剂司班(Span)系列与吐温(Tween)系列复配制备油包水(W/O)柴油微乳液;探讨了以下3种因素对柴油微乳液稳定性的影响:不同助剂醇、司班(Span)系列与吐温(Tween)系列不同配比、助剂醇(A)与表面活性剂(S)不同配比。并绘制了Span80/Tween80-柴油-正戊醇-水体系的一系列拟三元相图。最终得到形成柴油微乳的最适宜条件为:表面活性剂配比m(Span80)/m(Tween80)为4∶6;助剂为正戊醇;m(A)/m(S)为0.4。并利用亲水亲油平衡值理论(HLB值理论)和界面膜理论对试验结果进行分析。     

New Approach to Structure–Property Correlations of Different Films of Sorbitan Esters and Their Self-Assembly into Viscoelastic Monolayers

This publication is focused on the structural origin of viscoelasticity in Langmuir monolayers. To improve the understanding of the structural origin of viscoelasticity of surfactant films, we systematically studied interfacial films of different sorbitan esters with saturated (Span 60 and 65) and unsaturated (Span 80 and 85) paraffin chains by means of surface rheology, Langmuir isotherms, X-ray reflectometry (XRR), and Brewster angle microscopy (BAM). The results of two-dimensional shear rheological measurements revealed the existence of temporarily cross-linked networks. In dynamic BAM experiments, we observed a swinging motion of the monolayers as a result of a sudden externally initiated mechanical perturbation. The viscoelastic film response, which relaxed with time as the external force vanished, could be traced back to the presence of foam-like supramolecular structures that interlinked solid-condensed domains. The temperature dependence of the elastic response implied that the solid domains decomposed at temperatures close to the bulk melting point of Span 60 and Span 65. We concluded that insoluble surfactants formed solid domains at the interface, which were linked with each other by nonsolid areas, giving viscoelastic films. These newly discovered insights into coherent film formations could provide new opportunities for designing mechanically stable surfactant interfaces.     

Penicillin G extraction from model media using an emulsion liquid membrane: Determination of optimum extraction conditions

Penicillin G extraction by an emulsion liquid membrane (ELM) was investigated. The effects of surfactants, diluents, and carrier mixtures, together with their combined effects on the initial extraction rate and the emulsion stability were examined. Surfactants, diluents, and carriers used were Span80 (sorbitan monooleate)/ECA4360J (nonionic polyamine), n-butyl acetate/kerosene, and DOA (dioctylamine)/Amberlite LA-2 (secondary amine), respectively. The optimum extraction conditions were found to be 20% (v/v) of Span80 in ECA4360J as a surfactant, kerosene as a diluent and Amberlite LA-2 as a carrier.     

P_(204)/Span80/煤油/NaOH微乳体系萃取分离Ni~(2+)的研究

研究了以皂化P204和Span80为混合表面活性剂的微乳液配方及其稳定性,通过P204/Span80/煤油/NaOH微乳体系萃取分离N i2+的研究,考察了P204与煤油和Span80的质量比、NaOH的浓度、乳水比、外水相pH值、油相重复使用次数等因素对N i2+萃取率的影响。结果表明,当P204与煤油的质量比为1∶2.5,P204与Span80的质量比为1∶1,NaOH浓度为1.5 mol/L,乳水比为1∶5(体积比),废水pH值为5.5时,萃取10 m in,该微乳体系对N i2+萃取率可达99.9%。该微乳体系具有稳定性好、工艺简单、成本低、萃取效率高等优点。     

防垢功能纳米乳液制备与性能研究

以表面活性剂Span 80和Tween 80与正构烷烃为主要原料,应用正交设计实验方法优化出微乳液形成的最佳条件:油相选正庚烷或正辛烷,Span 80与Tween 80质量比(1∶1.5)～(1∶2),Span 80浓度3.9%～4.2%,正丁醇浓度7.0%～9.0%。将3种防垢成分FG-1、FG-2和FG-3分散于微乳液水相中,形成稳定均相的防垢纳米乳液。性能评价结果表明,含有防垢剂FG-1和FG-2的纳米乳液防垢率分别为90.1%和89.6%,与地层水接触后无絮凝物;含有FG-2的纳米乳液防垢剂吸附性好,解吸速率慢,并且高矿化度下仍有较好的防垢性能。与现用防垢剂商品相比,纳米乳液的防垢率随时间变化具有一个峰值,大大增加了防垢剂作用时间,提高了防垢效果,并对岩石渗透率有一定的修复能力。     

表面活性剂对球形纤维素珠体得率的影响

在成球过程中,分散剂种类及用量对珠体得率及粒径均有很大的影响。以N-甲基吗啉-N-氧化物(NMMO)和程序降温法制得的球形纤维素珠体为实验原料,以Span85、Tween80、Tween85、Span80和油酸钠等表面活性剂为分散剂,系统地研究了单种表面活性剂及表面活性剂混合对珠体制备的影响。实验结果表明,以Tween85为分散剂,用量为1.0%时,珠体得率最高,可达98.5%。以Tween85与十二烷基磺酸钠(SDS)的混合物(用量为4.0%)、Span85与Tween80的混合物(用量为1.5%)、十二烷基苯磺酸钠(SDBS)与SDS的混合物(用量为1.5%)为分散剂,所得球形纤维素珠体得率分别达到96.6%、95.8%、80.0%。     

耐高温厌氧胶的油面粘接性能改进

以乙氧化双酚A二甲基丙烯酸酯(BPA 2EODPT)、环氧丙烯酸酯(EA)和甲基丙烯酸羟丙酯(HPMA)为主体材料,BMI为耐热改性剂,添加SiO 2等无机填料以及Span 85等表面活性剂,制备出油面粘接性好的耐高温厌氧胶。结果表明,以破坏扭矩、平均拆卸扭矩、油面粘接强度损失率为考查指标,当w(SiO2)=4%~6%、w(Span 85)=0.4%时,油面粘接性能较优。     

Effect of temperature and span series surfactant on the structure of polysulfone membranes

A macrovoid structure was found in polysulfone membranes formed by the wet‐inversion method using N‐methylpyrrolidinone (NMP) and water as the solvent/nonsolvent pair. The addition of Span series surfactants in the casting solution was found to inhibit the macrovoid formation. Sorbitan monooleate (Span‐80) was more effective in inhibiting macrovoids than was sorbitan monolaurate (Span‐20). The phenomenon of macrovoid suppression became more prominent at higher temperature. The cloud‐point shift might account for the temperature effect. But there was no simple explanation for the effect caused by Span‐80. The cloud‐point position, the demixing rate, and the viscosity of the casting solution were measured. None of them could explain the effect of macrovoid inhibition by the addition of Span‐80. However, the penetration test indicated that the penetration of a nonsolvent into a surfactant‐free casting solution was caused by a convective flow, but that into Span‐80 was through diffusion. It was found that the retardation of nonsolvent penetration was the major cause of macrovoid inhibition. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 166–173, 2002     

Destabilization of Emulsion Formed During Aqueous Extraction of Peanut Oil: Synergistic Effect of Tween 20 and pH

To destabilize the emulsion formed during aqueous extraction processing (AEP) of peanuts, Tween and Span series surfactants (Tween 20, Tween 80, Span 20, and Span 80) were used alone or in combination to break the emulsion. Results indicate that only Tween surfactants had a pronounced demulsifying effect that was dependent on Tween concentration and system pH. When 1.2 wt% Tween 20 aqueous solution was used for oil extraction at pH 10.0, the highest free oil yield was achieved at 76.1 %, which was similar to the oil recovery of using proteases as a destabilization agent. The results obtained using a model emulsion system containing peanut oil and Tween 20/peanut protein isolates (PPI) showed that when Tween 20 and PPI coexisted in extraction medium at pH 10.0, the dynamic interfacial tension and droplet size distribution curves were very similar to those when Tween 20 was used alone, suggesting that Tween 20 dominated at the interface, instead of PPI. Destabilization of the model emulsions relied on three important factors: inclusion of Tween 20 at the initial mixing stage, high pH, and a gentle mixing speed. A synergistic destabilization mechanism of using Tween 20 at high pH during AEP was proposed. The discovery of Tween 20 as an effective demulsifier significantly contributes to the development of AEP of oilseeds.     

Synthesis and Properties of a Series of CO2 Switchable Surfactants with Imidazoline Group

Switchable surfactants are environment-friendly compounds, which can be separated from the system or lose surface activity after completing their function during one stage of a process. In order to study switchable properties of a kind of CO₂ switchable surfactant with an imidazoline group, four 2-alkyl-1-hydroxyethylimidazolines were synthesized by condensation of N-(2-hydroxyethyl)ethanediamine with dodecanoic, tetradecanoic, hexadecanoic, and octadecanoic acids. Then, the series of long-chain alkyl imidazoline compounds were reacted with dry ice to produce imidazolinium bicarbonates cationic surfactants. The critical micelle concentration (CMC) and surface tension at CMC (??_cmc) measured by the Wilhelmy plate technique show that these surfactants have excellent surface activity. The changes of conductivity before and after bubbling CO₂ show the conversion between imidazolines and imidazolinium bicarbonates cationic surfactants. Conductivity cycles indicated that these surfactants could be switched by CO₂ reversibly and repeating this three times. However, their switchable function on the emulsification-demulsification of water-alkane was dissatisfactory due to the emulsibility of amide which was hydrolyzed from 2-alkyl-1-hydroxyethylimidazoline. Therefore, the application of these switchable surfactants needed to be studied further.     

Synthesis of spherical zirconia by precipitation between two water/Oil emulsions

Microparticles of ZrO₂ are produced by using precipitation method between two emulsion solutions. First, two solutions of stable reverse emulsion (water-in-oil) are prepared and mixed to form gelled precipitates, using normal heptane as the continuous oil phase and aqueous solutions of zirconium oxyacetate and aqueous ammonia as the suspending droplets. Through a series of operations, including distillation, filtration and washing, the dried precursors are obtained. After calcining the precursors at 750°C, ZrO₂ powder with a tetragonal structure is obtained. Principle factors that influence the emulsion stability, which subsequently affects the morphology and particle size of ZrO₂ powder, are investigated, including the type and concentration of surfactant, volume ratio of water/oil, concentration of solute in water phases, and mixing intensity and time for emulsion formation. Four kinds of anionic surfactants are put to test for emulsion stability; among them Span 40 and Span 80 are considered as suitable surfactants for producing spherical microparticles of ZrO₂, which has a size range from several hundred nanometers to micrometers depending on the synthesis conditions. ©     

Synthesis,Characterization, Surface and Biological Activity of Diquaternary Cationic Surfactants Containing Ester Linkage

Two series of diquaternary cationic surfactants designated as E9Nm and E11Nm having two different alkyl chains in their chemical structure were synthesized. The chemical structures of these surfactants were confirmed using elemental analysis, FTIR and ¹H‐NMR spectra. The surface activities of the different surfactants were determined using surface and interfacial tension at 25 °C. The surface parameters including: critical micelle concentration, effectiveness, efficiency, maximum surface excess and minimum surface area were determined. The surface activities of the cationic surfactants were correlated with their chemical structure. The surface activities of the surfactants increased with increasing the hydrophobic chain length. The adsorption and micellization tendencies of the surfactants in solution were determined using the free energies of adsorption and micellization. The synthesized surfactants were evaluated as biocides against bacteria and fungi. Biocidal activity data showed that a gradual increase in the hydrophobic chain length of the surfactant molecules gradually increases the efficiency of these surfactants as biocides.