Partitioning equilibria in multicomponent surfactant systems for design of surfactant-based extraction processes

Aqueous biphasic systems based on nonionic surfactants have perspective applications in extraction processes, in particular, cloud point extraction of hazardous compounds or high valued products, especially biomolecules. Additives (e.g., ionic surfactants, salts) and variations in pH can significantly affect the surfactant-based separation processes, representing an additional degree of freedom for their optimization. However, there are few systematic studies of phase and partition behavior for these multicomponent surfactant systems.In this study we examined the clouding, phase compositions and partitioning equilibria for aqueous mixed surfactant systems of a nonionic surfactant (Triton X-114), ionic surfactants (cetyltrimethylammonium bromide or sodium dodecyl sulfate) and NaCl, in order to improve the extraction efficiency. Vanillin was used as a model substance at three different pH values, specifically in (partly) dissociated or non-dissociated states. The partition coefficients obtained in the batch experiments were compared to the predictions by the thermodynamic model COSMO-RS. Based on this knowledge a continuous multistep extraction process was carried out.To the best of our knowledge this is the first demonstration of using a mixed surfactant system for continuous countercurrent cloud point extraction.     

Compatibility of nonionic surfactants with membrane materials and their cleaning performance

Membranes applied in industrial processes, such as for the desalination of seawater as well as for dairy and beverage industry are subjected to fouling resulting in a decline of their performance. In order to regain the flux of the membranes, cleaning procedures are conducted, whereby inorganic scale is often removed with acids and organic matter with surfactants under alkaline conditions. Currently, either ionic surfactants or alkylphenol ethoxylates are utilised to clean membranes of organic matter. Other nonionic surfactants (i.e. fatty alcohol ethoxylates) are not applied, due to the assumption that they irreversibly adhere to the membrane surface and thereby clog the pores. At BASF we have studied the adsorption of a wide range of nonionic surfactants to membrane materials. It was shown, that the affinity of nonionic surfactants critically depends on their structure. Linear alkyl ethoxylates irreversibly adsorb to the membrane surfaces, whereas branched alkyl ethoxylates do not. In a second step, we tested the cleaning performance of nonionic surfactants. Similar to the results for adsorption, a structure-performance relationship was discovered where several branched alkyl ethoxylates showed excellent cleaning results. In a third step, combinations of nonionic surfactants, chelating agents and enzymes were tested in terms of cleaning efficiency. All tested combinations showed excellent cleaning performance on bacterial fouling layers.     

聚醚型非离子表面活性剂的浊点及其影响因素

总结了非离子表面活性剂浓度、外加聚合物、离子表面活性剂、无机电解质、助表面活性剂等对聚醚型非离子表面活性剂水溶液浊点的影响规律 ,发现聚合物由于其结构和分子量不同对浊点的影响也不同 ,一般可使浊点降低 ;加入离子表面活性剂可以和非离子表面活性剂形成混合胶束 ,从而使浊点升高 ;无机盐由于存在盐析和盐溶两种不同效应而对浊点的影响比较复杂 ;醇和有机酸等助表面活性剂根据其碳链的长短不同而影响浊点。这些规律对非离子表面活性剂的研究和应用有一定的指导意义。     

10％辛硫磷水乳剂的研究

用Span20和Tween20以不同比例复配对10%辛硫磷进行乳化,发现复配乳化剂的最佳HLB值为11.5。再根据此HLB值选择出由阴离子表面活性剂和非离子表面活性剂组成的乳化剂对,确定了最佳乳化剂对。乳化剂的用量为2%,加入0.5%的助乳化剂十六醇和0.1%的增稠剂可明显提高水乳剂的稳定性。     

Identification of polyoxyalkylene-type nonionic surfactants by paper chromatography

Despite the increasing importance of nonionic surfactants, methods for their identification have been limited to specific groups. Accordingly, a general analytical scheme for the identification of polyoxyalkylene-type nonionic surfactants was developed, which uses qualitative tests and two paper chromatographic solvent systems. This procedure differentiates among the ethoxylates of alcohols, thioalcohols, alkyl phenol, fatty acids, polyoxyethylene polyoxypropylene acids, sorbitan fatty esters, fatty amides, polyoxyethylene glycols (PEG) condensates. In addition, individual members of a class can be separated and identified. The method is applicable to a variety of detergent products and to mixtures of more than one nonionic. As little as 7 mg of a nonionic surfactant are sufficient for complete characterization. Presented at the AOCS Meeting, Washington, D.C., April, 1968.     

Neuere Entwicklungen auf dem Gebiet fettchemischer Tenside

New Developments in the Field of Oleochemical Surfactants A large area of application for fats and oils in the technical field is the manufacture of surfactants. The oleochemical industry has long been making intensive efforts to gain a still greater share of the world's surfactant production for oleochemical surfactants. There are some promising conditions to reach this goal. New developments in the field of anionic and nonionic surfactants are summarized in an overview. There will be discussed fatty alcohol sulfates (especially tallow alcohol sulfate), α-sulfo-fatty acid methylesters, acyl cyanamides, non-terminal fatty acid methylester sulfonates (by sulfoxidation of saturated fatty acid methylesters and by SO₃-sulfonation of unsaturated fatty acid esters), oleic acid sulfonates, alkyl- and alkenyl ether sulfonates, hydroxy alkyl ether sulfates, alkyl glucosides, fatty alcohol polyethyleneglycol alkyl ethers and -hydroxyalkyl ethers and narrow range fatty alcohol ethoxylates. The development work on new oleochemical surfactants which has been described permits the conclusion that in future oleochemical surfactants will further increase their share of world surfactant production.     

On-Line Thermospray-LC-MS von nichtionischen Tensiden

On-line Thermospray-LC-MS of Nonionic Surfactants Nonionic surfactants are often homologues with different degrees of ethoxylation. In addition, many products contain mixtures of nonionic surfactants, which differ in their chemical nature (e.g. polyglycol ethers of fatty alcohols and nonylphenol, sorbitan esters, fatty acid alkanolamides). For the analysis of such complex mixtures efficient separation methods are necessary: Thin layer chromatography is frequently applied to determine the type of surfactant. However, problems arise in quantitative evaluation and in determination of the hydrocarbon chain-distribution. The applicability of gaschromatography is limited by the requirements of volatility and thermal stability. Liquid chromatography should be an appropriate method for quantification, provided chromatographic resolution is sufficient. However, the identification is difficult if a refractive index detector is used because in such complex mixtures overlapping peaks are to be expected. For these reasons a universal and specific detector is required. In this contribution it is shown that the mass spectrometer may be linked to a liquid chromatograph by means of a modern Thermospray-Interface. This technique may be favourably applied to the analysis of nonionic surfactants.     

Oily soil removal from a polyester substrate by aqueous nonionic surfactant systems

Pure mineral oil soils are removed from polyester substrates by the roll-up mechanism in nonionic surfactant systems, and the process is little affected by hardness ions or builder addition. For a given surfactant system, roll-up and removal efficiency increase with temperature until the cloud point of the nonionic is reached, whereafter a further increase in temperature decreases the rate of roll-up. In general, lower ethoxylated surfactants perform better than higher ethyxylates at low temperature, but the trend is gradually reversed as the temperature is increased. For a given degree of ethoxylation, secondary alcohol ethoxylates are more effective at rolling up mineral oil soils than their primary counterparts. Addition of a small amount of oleic acid to mineral oil soils facilitates the roll-up process (by lowering the oil/water interfacial tension) and minimizes the differences in performance among the various types of unbuilt nonionic surfactants. However, addition of highly alkaline electrolytic builders with these soils promotes oil removal by emulsification, presumably because of charge neutralization and/or transfer of the fatty acid into the aqueous phase. Conditions of high pH and low electrolyte strength inhibit the removal of 5.0% oleic acid in mineral oil soils, as exemplified by studies with added triethanolamine, ammonia, and very diluted NaOH. However, addition of divalent hardness ions to such systems promotes coarse emulsification of the soil, as does addition of relatively high concentrations of monovalent cation salts. A tentative explanation of this phenomenon is proposed. Ionic strength has little effect on the removal of 5.0% oleic acid/mineral oil soils below pH 7, as rapid roll-up is obtained regardless of added electrolytes. Similarly, ionic strength (or pH) has little effect on the removal of mineral oil containing polar, but nonionizing soils such as oleyl alcohol, as rapid rollup is achieved under a number of conditions.     

Synthesis of open porous emulsion-templated monoliths using cetyltrimethylammonium bromide

In recent years, open porous materials (polyHIPEs) have attracted more and more attention because of their specific properties and applications in biological tissue scaffolds, catalysis supports and ion-exchange resin. However, the surfactants used in this type material were limited to nonionic surfactants or the mix of nonionic surfactant and ionic surfactant. In this work, firstly well-defined polyHIPEs were synthesized by W/O emulsions with ionic surfactant alone (e.g., CTAB). Furthermore, the polyHIPEs with much higher pore volume (14.7 cm³ g⁻¹), uniform pore diameter and cell size were obtained by this method. Both the median pore diameter and average cell size of the polyHIPEs rose with increase of DVB concentration and/or water fraction.     

Gel filtration of surfactants

A simulation technique was developed for analyzing the gel filtration chromatography of surfactants. Theoretical elution curves obtained by this technique were compared with the experimental curves for the following five systems: an ionic or a nonionic surfactant of a single component, an ionic surfactant in the presence of an electrolyte, a mixture of two nonionic surfactants, a mixture of two ionic surfactants, and a mixture of an ionic and a nonionic surfactant. In the first four systems, good agreement was found between the theoretical and experimental elution curves. A possible explanation for the disagreement in the last system is presented.     

Cleavable Surfactants: A Comparison between Ester,Amide, and Carbonate as the Weak Bond

Cleavable surfactants, i.e., surfactants in which a weak bond has deliberately been inserted into the molecule, are of interest when remaining surface-active material at a surface can cause problems. Ester and amide bonds are established as week linkages in surfactants but these generate an acid when they hydrolyze. For some applications, acidic degradation products are unwanted. Surfactants with a carbonate bond between the polar headgroup and the hydrophobic tail are of interest for such purposes. In this article, we compare the physical–chemical properties of nonionic carbonate surfactants with those of the corresponding ester and amide surfactants. The half-lives of the different cleavable surfactants are also compared and it was found that a carbonate bond is slightly more stable to alkaline hydrolysis than an ester bond when present in otherwise identical structures. A nonionic Gemini surfactant with a carbonate bond in the spacer, which on hydrolysis decomposes into two identical single-tailed nonionic amphiphiles, is also presented. The hydrolysis kinetics for this surfactant was studied in some detail and it was found that it degrades much faster at low temperature than at higher temperature. This anti-Arrhenius type of hydrolysis kinetics is proposed to be due to the reverse solubility versus temperature behavior of ethoxylated surfactants.     

Review: Implementing the hydrophilic–lipophilic deviation model when formulating detergents and other surfactant-related applications

When designing surfactant formulations using ionic and nonionic surfactants, the hydrophile lipophile balance (HLB) is a generalized surfactant characterization parameter that has shown to be useful when designing surfactant formulations, in the case of both ionic and nonionic surfactants (Davies' and Griffin's methods). Microemulsion phase behavior studies have been extensively used to optimize surfactant formulations, but these studies can cover a very wide phase space and can often encounter troublesome non-equilibrium issues such as coacervation. Detailed phase behavior studies can be time-consuming and difficult to apply beyond the specific surfactant-oil system studied. The hydrophilic–lipophilic deviation (HLD) provides a method to help expedite surfactant formulation research by reducing the number of phase behavior studies required to optimize a given formulation. Detergency experiments have indicated that there is an optimal range of HLD for a given fabric surface. This appears to apply to other applications, as well, for example, surfactant formulations used in enhanced oil recovery have been optimized using the HLD method. These studies found that the HLD can reflect total oil recovery, even if the surfactants were derived from different alcohol feedstocks (e.g., HLD of 0 would describe optimum conditions regardless the type of surfactant). Also with additional parameterization, the HLD method can also be applied to non-ideal surfactant mixtures, specifically ionic/nonionic blends. Overall, the HLD framework has shown to be an effective screening tool for a wide range of surfactant-related applications when appropriate experiments, assumptions, and understanding of surfactant and oil interactions are used to generate the HLD parameters.     

Alkyd emulsions

Various aspects of alkyd emulsion technology have been investigated. The influence of alkyd oil length, acid value and hydroxyl number and type of surfactant used as emulsifier, on shear stability of alkyds emulsions have been studied. It was found that the acid value was the most important alkyd parameter, the stability increasing with increasing oil length. It is also shown that anionic surfactants give emulsions with small droplet sizes at lower concentrations than do nonionics. Polymerizable nonionic surfactants have been tested as emulsifiers and compared with conventional surfactants of the same hydrophilic lipophilic balance (HLB). It was found that surfactants capable of participating in the autoridative curing process give faster drying and improved film hardness compared with nonreactive surfactants. The distribution of driers between the alkyd phase and the water phase has been investigated. It was found that low pH and the use of hydrophilic anionic surfactants, such as sodium dodecyl sulphate, favour partitioning of cobalt into the aqueous phase which is unfavourable with respect to drying properties.     

乙草胺微乳液的研究

采用拟三元相图的方法研究了乳化剂和助乳化剂对乙草胺微乳液区域的影响,确定非离子表面活性剂采用酚醚,阴离子表面活性剂为十二烷基苯磺酸钙,助表面活性剂使用正丁醇,最佳乳化剂配方:非离子表面活性剂、阴离子表面活性剂、助表面活性剂的质量比为5:2:3.通过电导率测定,确定了乙草胺,乳化剂,水三元体系中乳液区的W/O、O/W类型.通过对液晶现象观察,绘制了在混合制剂(A)/混合制剂(T)/水拟三元相图中液晶区域范围.并讨论了微乳剂配制过程中的相行为变化.     

Synergistic Effect of Mixed Surfactant Systems on Foam Behavior and Surface Tension

Foam and surface tension behaviors of different ionic/nonionic surfactant solutions along with their different combinations have been investigated. Among different surfactants, sodium dodecyl sulfate showed the highest foamability over other surfactants. Mixed surfactant systems were always found to have higher foamability than the individual surfactant. It was also noticeable that nonionic surfactants show good foamability when they combine with anionic and cationic surfactants. In the case of mixed surfactant systems, nonionic/cationic surfactant mixtures showed lower surface tension than nonionic/anionic surfactant mixture due to a synergistic effect.     

偏氯乙烯／丙烯酸甲酯乳液共聚合研究

以过硫酸钾／亚硫酸氢钠（ＫＰＳ／ＳＨＳ）为引发体系，十二烷基苯磺酸钠（ＳＤＢＳ）或十二烷基硫酸钠／聚氧乙烯基辛基酸醚（ＳＬＳ／ＯＰ）为乳化剂或复合乳化剂，于５０℃或６０℃下进行偏氯乙烯／丙烯酸甲酯（ＶＤＣ／ＭＡ）的乳液共聚合。实验结果表明，采用乳化剂ＳＤＢＳ或复合乳化剂ＳＬＳ／ＯＰ，加入适量离子型第三单体和ｐＨ值调节剂，可以制得总固物含量大于５０％的稳定性好、粒径适宜、阻透和涂敷性能良好的ＶＤＣ／     

添加剂的浓度对非离子表面活性剂AEO9浊点的影响

各类添加剂都能对非离子表面活性剂的浊点产生影响.今研究了离子型表面活性剂、增溶物和电解质类添加剂在不同浓度下对非离子表面活性剂AEO9浊点的影响.其中离子型表面活性剂和增溶物类添加剂可在极低的浓度上改变AEO9的浊点,且随着添加剂加入浓度的增加,AEO9的浊点也逐渐增加,当添加剂浓度达到离子型表面活性剂或增溶物的临界胶束浓度时,AEO9的浊点将出现急剧上升.而电解质类添加剂对AEO9浊点的影响表现出具有临界浓度现象,只有当添加剂的浓度达到相应的临界浓度之后,具有盐析效应的电解质将使AEO9浊点线性下降,而具有盐溶效应的电解质则使AEO9浊点线性升高,且不同电解质相应的临界浓度随着其阴离子的感胶离子数的增大而线性增加,同时其对AEO9浊点的改变程度则随着阴离子的感胶离子数的增大而线性下降.     

反胶团系统及蛋白质萃取过程研究进展

综述了反胶团系统和蛋白质萃取过程,将反胶团萃取系统按单一反胶团系统、混合反胶团系统和亲和反胶团系统划分,强调了研究开发生物相容性表面活性剂以及在反胶团系统中引入亲和作用的重要性。另外,指出了深入开展反胶团萃取设备和过程研究的必要性。     

Surface activity of mixtures of narrow-range distributed alcohol oxyethylates and sodium dodecylbenzenesulfonate

Surface and interfacial tension, emulsion inversion temperature, and detergency were determined for mixtures of sodium dodecylbenzenesulfonate and narrow-range distributed alcohol C₁₂−C₁₄ oxyethylates of different hydrophilicity. The mixtures of ionic and nonionic surfactants behave similarly to nonionic and ionic surfactants at the air/water and hydrocarbon/water interfaces, respectively. The air/water interface is mainly occupied by nonionic surfactant molecules. However, the interfacial tensions for mixtures of nonionic and ionic surfactants are similar to those of sodium dodecylbenzenesulfonate. Mixtures of narrow-range distributed oxyethylates and sodium dodecylbenzenesulfonate have a higher detergency at 40°C than individual components.     

Sugar fatty acid ester surfactants: Structure and ultimate aerobic biodegradability

Ultimate aerobic biodegradabilities of an array of sugar ester surfactants were determined by International Standards Organisation method 7827, “Water Quality—Evaluation in an Aqueous Medium of the Aerobic Biodegradability of Organic Compounds, Method by Dissolved Organic Carbon” (1984). The surfactants were nonionic sugar esters with different-sized sugar head groups (formed from glucose, sucrose, or raffinose) and different lengths and numbers of alkyl chains [formed from lauric (C₁₂) or palmitic (C₁₆) acid]. Analogous anionic sugar ester surfactants, formed by attaching an α-sulfonyl group adjacent to the ester bond, and sugar esters with α-alkyl substituents were also studied. It was found that variations in sugar head group size or in alkyl chain length and number do not significantly affect biodegradability. In contrast, the biodegradation rate of sugar esters with α-sulfonyl or α-alkyl groups, although sufficient for them to be classified as readily biodegradable, was dramatically reduced compared to that of the unsubstituted sugar esters. An understanding of the relationship between structure and biodegradability provided by the results of this study will aid the targeted design of readily biodegradable sugar ester surfactants for use in consumer products.