Efficient promotion of methane hydrate formation and elimination of foam generation using fluorinated surfactants

Methane hydrate preparation is an effective method to store and transport methane. In promoters to facilitate methane hydrate formation, homogeneous surfactant solutions, sodium dodecyl sulfate (SDS) in particular, are more favorable than heterogeneous particles, thanks to their faster reaction rate, more storage capacity, and higher stability. Foaming, however, could not be avoided during hydrate dissociation with the presence of SDS. This paper investigated the ability of five fluorinated surfactants: potassium perfluorobutane sulfonate (PBS), potassium perfluorohexyl sulfonate (PHS), potassium perfluorooctane sulfonate (POS), ammonium perfluorooctane sulfonate (AOS), and tetraethylammonium perfluorooctyl sulfonate (TOS) to promote methane hydrate formation. It was found that both PBS and PHS achieve a storage capacity of 150 (V/V, the volume of methane that can be stored by one volume of water) within 30 min, more than that of SDS. Cationic ions and the carbon chain length were then discussed on their effects during the formation. It was concluded that PBS, PHS, and POS produced no foam during hydrate dissociation, making them promising promoters in large-scale application.     

Aggregation Behavior,Antibacterial Activity and Biocompatibility of Catanionic Assemblies Based on Amino Acid-Derived Surfactants

The surface activity, aggregates morphology, size and charge characteristics of binary catanionic mixtures containing a cationic amino acid-derived surfactant N(π), N(τ)-bis(methyl)-L-Histidine tetradecyl amide (DMHNHC₁₄) and an anionic surfactant (the lysine-based surfactant N^α-lauroyl-N^εacetyl lysine (C₁₂C₃L) or sodium myristate) were investigated for the first time. The cationic surfactant has an acid proton which shows a strong pK_a shift irrespective of aggregation. The resulting catanionic mixtures exhibited high surface activity and low critical aggregation concentration as compared with the pure constituents. Catanionic vesicles based on DMHNHC₁₄/sodium myristate showed a monodisperse population of medium-size aggregates and good storage stability. According to Small-Angle X-Ray Scattering (SAXS), the characteristics of the bilayers did not depend strongly on the system composition for the positively charged vesicles. Negatively charged vesicles (cationic surfactant:myristate ratio below 1:2) had similar bilayer composition but tended to aggregate. The DMHNHC₁₄-rich vesicles exhibited good antibacterial activity against Gram-positive bacteria and their bactericidal effectivity declined with the decrease of the cationic surfactant content in the mixtures. The hemolytic activity and cytotoxicity of these catanionic formulations against non-tumoral (3T3, HaCaT) and tumoral (HeLa, A431) cell lines also improved by increasing the ratio of cationic surfactant in the mixture. These results indicate that the biological activity of these systems is mainly governed by the cationic charge density, which can be modulated by changing the cationic/anionic surfactant ratio in the mixtures. Remarkably, the incorporation of cholesterol in those catanionic vesicles reduces their cytotoxicity and increases the safety of future biomedical applications of these systems.     

邻苯二甲酸单醇醚钠盐润湿性能研究

用帆布沉降法对邻苯二甲酸单脂肪醇聚氧乙烯（３）醚酯钠盐（简称ＰＡＥＳ）新型表面活性剂的润湿性能进行了系统研究,测定了其在不同质量分数、不同温度、不同硬度水中的润湿性能,并与两种同类表面活性剂ＡＥＳ,ＡＥＳＭ的润湿性能进行了对比。结果表明,ＰＡＥＳ是一种润湿渗透性能优异的表面活性剂新品种。     

Prediction and measurement of surfactant action upon human skin under realistic conditions

The lysosomal enzyme acid phosphatase has been characterized and quantified in tapestrip biopsies of human stratum corneum by means of a sensitive spectrofluorometric procedure. When the stratum corneum of panellists was exposed to dilute solutions of various surfactants under realistic exposure conditions, the changes observed in stratum corneum acid phosphatase specific activity have been found to correlate very closely with the visual, macroscopic changes such as dryness and flakiness, that are elicited in skin as a result of surfactants. This method monitors denaturation of stratum corneum proteins, which is an important feature of skin surfactant interactions, and serves as an effective, non-invasive predictive tool for skin irritancy and mildness of surfactants.
Prevention et mesure de l'action des tensio-actifs sur la peau humaine dans des conditions conformes a la réalité     

阳离子表面活性剂在羊毛纤维上吸附的计量置换模型研究

对于有关文献报道的常温下阳离子表面活性剂在羊毛纤维上吸附的实验数据，用液/固吸附计量置换模型（SDM-A）研究了线性吸附参数βα和解吸参数q/z。由这些线性参数不仅成功地解释了加盐效应及碳氢链长对于吸附性质的影响事实，而且依据SDM-A的热力学计算出不同吸附体系的吸附亲和能、解吸能及置换吸附总过程的自由能，以便认识吸附机理的细节。     

Investigation of the synergistic effect of alumina nanofluids and surfactant on oil recovery – Interfacial tension,emulsion stability and viscosity reduction of heavy oil

In order to understand the synergistic effect of surfactants and nanofluids on enhancing recovery, hydrophilic and hydrophobic alumina nanomaterials were prepared for alumina nanofluids with surfactants. Oil-water interfacial tension and emulsion stability were investigated. The experimental results showed that nanofluids cooperated with surfactants could reduce oil-water interfacial tension in the proper concentration range, Nanoparticles decreased the average size of droplets, and restrained creaming and coalescence, therefore stabilizing the emulsion. The effect of nanofluids on the viscosity of heavy oil was also tested. The results indicated that the viscosity of heavy oil with surfactants was reduced by 42.8% when nanofluids were added at the shear rate of 10 s^?1.     

Rheological characterization of hair shampoo in the presence of dead sea salt

In Jordan, a growing industry has been established to produce different types of Dead Sea (DS) cosmetics that have DS salt (contains mainly NaCl, KCl, and MgCl(2)) in their formulas. In this work, the effect of DS salt on the rheology of hair shampoo containing the sodium lauryl ether sulfate as a main active matter was studied. The effects of DS salt and active matter concentration, and the temperature and time of salt mixing, on the rheological properties of hair shampoo were investigated. The salt-free shampoo showed a Newtonian behavior at 'low active matter' (LAM) and shear thinning at 'high active matter' (HAM). The presence of DS salt changed the rheological behavior of LAM shampoo from Newtonian (for the salt-free shampoo) to shear thinning. On the other hand, the behavior of HAM shampoo switched from shear thinning to Newtonian behavior in the presence of high concentration of DS salt. The addition of DS salt increased the apparent viscosity of shampoo to reach a maximum value that corresponded to a salt concentration of 1.5 wt.%. Further addition of DS salt led to a decrease in the shampoo viscosity to reach a value less than that of the salt-free sample at high salt concentration. Changing the mixing temperature (25-45 degrees C) and mixing time (15-120 min) of DS salt with shampoo has no significant influence on the rheological behavior. However, the mixing process increased the apparent viscosity of salt-free shampoo. The power law model fitted well the flow curves of hair shampoo with and without DS salt.     

阳离子松香乳液的制备及其施胶性能

用环氧氯丙烷、三乙胺与松香反应制备了松香型阳离子乳化剂,不需加其他表面活性剂,单独用15%的该乳化剂与本实验室自制的阳离子聚合物乳液作分散剂对松香进行乳化,采用常压逆转法制备了阳离子松香乳液,并对该乳液的施胶性能进行了探讨.     

Alginate‐Based Emulsion Template Containing High Oil Loading Stabilized by Nonionic Surfactants

Oil‐in‐water (O/W) emulsion‐gel systems containing high oil payloads are of increasing interest for food applications because of the reduction in encapsulation cost, consumption frequency or volume of food products. This study shows a facile approach to prepare stable alginate‐based O/W emulsions at high oil loading using a mixture of nonionic surfactants (Tween 80 and Span 20) as a template to form gelled‐emulsions. The synergistic effects of alginate and surfactants on the O/W emulsion properties were evaluated in terms of oil droplet size and emulsion stability. At 2% (w/v) of alginate and 1% (w/v) of surfactants, the size distribution of oil droplets was narrow and monomodal, even at an oil loading of 70% (v/v). The emulsions formed were stable against phase separation. The oil droplet size could be further reduced to below 1 μm using a high‐shear homogenizer. The emulsions formed could be easily molded and gelled into solids of different shapes via ionic gelation. The findings of this study create possible avenues for applications in food industries.     

氟硅酸钠的防结块研究

分折了氟硅酸钠结块的原因，介绍了防结块的措施，并对表面活性剂和惰性物质应用于氟硅酸钠的防结块进行了研究。结果表明，硫酸巴盐或磺酸盐型表面活性剂应用于氟硅酸钠的防结块效果显著，选用复配型表面活性剂，即磺酸盐和脂肪酸盐等的复配液效果更佳，用量为0．12％时能确保氟硅酸钠70d不结块。