Dissolution of Soap Scum by Surfactant Part I: Effects of Chelant and Type of Soap Scum

The equilibrium solubilities of two model soap scums [calcium stearate and magnesium stearate: Ca(C₁₈)₂ and Mg(C₁₈)₂] were measured in aqueous solutions containing three different types of surfactants: methyl ester sulfonate (MES) as an anionic; alcohol ethoxylate (EO9) as a nonionic; and dimethyldodecylamine oxide (DDAO) as an amphoteric with and without a chelating agent [disodium ethylenediaminetetraacetate (Na₂EDTA)]. The solubility of calcium soap scum was generally higher than that of magnesium soap scum, the exception being some DDAO systems. The use of the DDAO surfactant with the Na₂EDTA chelating agent at high pH gives the highest solubilities of both studied soap scums. The soap scum solubility is on the order of 2,000 times that in water at high pH. The DDAO is the most effective surfactant under all conditions. The MES is more effective than the EO9 at low pH with the opposite trend observed at high pH. The synergism from added chelant is generally greater at higher pH and is greatest for DDAO followed by EO9.     

Dissolution of Soap Scum by Surfactant. Part II: Effects of NaCl and Added Chelant on Equilibrium Solubility and Dissolution Rate of Calcium Soap Scum in Amphoteric Surfactant Solutions

The effects of solution pH and NaCl on the equilibrium solubility and dissolution rate of a model soap scum (calcium octadecanoate or calcium stearate) in aqueous solutions of dimethyldodecylamine oxide surfactant (DDAO) with and without chelant disodium ethylenediaminetetraacetate are reported. The equilibrium solubility and dissolution rate of soap scum increased with increasing solution pH when the chelant was added in the DDAO system while in the chelant-free systems the opposite trend was observed. The added NaCl has an ambiguous effect on the solubility and dissolution rate of soap scum in the absence of chelant, but a small level of added NaCl reduces both solubility and the dissolution rate constant in the presence of chelant. Both equilibrium and kinetics of dissolution are maximized at high pH with DDAO/chelant and no added salt.     

Dissolution of Soap Scum by Surfactants. Part III. Effect of Chelant Type on Equilibrium Solubility and Dissolution Rate of Calcium and Magnesium Soap Scums in Various Surfactant Systems

Soap scum can be effectively removed by using an appropriate surfactant with a chelating agent at a high solution pH. The equilibrium solubilities and dissolution rates of two model soap scums [calcium stearate and magnesium stearate: Ca(C₁₈)₂ and Mg(C₁₈)₂] were investigated in aqueous solutions containing three different types of surfactants [methyl ester sulfonate (MES) as an anionic surfactant; alcohol ethoxylate (EO9) as a nonionic surfactant; and dimethyldodecylamine oxide (DDAO) as an amphoteric surfactant] in the presence of different biodegradable chelants: trisodium ethylenediamine disuccinic acid (Na₃EDDS) and tetrasodium glutamate diacetic acid (Na₄GLDA) compared with disodium ethylenediamine tetraacetate (Na₂EDTA), a chelant with poor biodegradability. The highest equilibrium solubility and dissolution rate of either soap scum were observed at high pH in the DDAO system with Na₄GLDA. In addition, the calcium soap scum had a similar to higher equilibrium solubility and a higher dissolution rate constant as compared with the magnesium soap scum.     

9,10,12,13-四羟基硬脂酸钠在低温硬质水及中性pH条件下的特异性能

以天然亚油酸为原料,经氧化水解制备得到9,10,12,13-四羟基硬脂酸(THSA),采用FTIR、ESI-MS和1HNMR表征了THSA的结构。测定了THSA的钠皂9,10,12,13-四羟基硬脂酸钠(STHS)的克拉夫特点、钙离子稳定性、钙皂分散剂消耗量、表面张力、临界胶束浓度和泡沫性能,并与对照物亚油酸、油酸及硬脂酸的钠皂进行比较。结果表明,STHS具有其他脂肪酸钠皂不具备的优秀钙皂分散性能和钙离子稳定性,并在低温和中性条件下显示出更好的水溶性。STHS不仅克服了普通脂肪酸钠皂不耐硬水和中性条件下溶解性差两大共同缺陷,也克服了饱和脂肪酸钠皂低温溶解性差以及不饱和脂肪酸钠皂易氧化酸败的缺点,因此,STHS具有在中性皂、低温皂和抗硬水皂配方中用作新皂基表面活性剂的潜质。     

Liquid laundry detergents based on soap andα-sulfo methyl esters

It is well known that soap is one of the most effective cleaning agents in soft water. However, soap is equally notorious for some of its deficiencies, especially formation of soap scum due to the precipitation of calcium and magnesium soaps in hard water, low solubility in water, poor cleaning in cold water, greying of fabrics and dulling of hard surfaces such as ceramic tiles. Attributes of soap that should not be overlooked, especially in today’s environment, include an abundant and natural raw material supply (vegetable oils and fats) and excellent human and environmental safety profiles that are superior to most synthetic surfactants. Presented in part at an AOCS/CSMA Detergent Industry Conference, Hershey, Pennsylvania, October 31, 1989.     

Soap and lime soap dispersants

In recent decades, soap has largely been replaced by petrochemicals and polyphosphates as the major components of laundry detergents in the U.S. Currently, the use of soap is primarily confined to the toilet soap bar field, and technological advances here have been mainly in processing. In view of the rising costs and increasing scarcity of petrochemicals and polyphosphates, tallow, a replenishable, inexpensive agricultural by-product, was examined as an alternate raw material. Tallow soap has a long history of efficacy and safety but suffers from poor performance in hard water and insolubility in cold water. It has now been shown that the performance of soaps can be drastically improved in cold water solubility and in hard water detergency by the addition to the soap of lime soap dispersing agents (LSD A). These are anionic or amphoteric surfactants possessing one or more bulky polar groups. These soap-LSDA combinations form mixed micelles in water and essentially take on the surface active characteristics of a single anionic surfactant. Soap-LSDA combinations wash well in hard water without curd formation; they can be “built” with various materials such as phosphates and trisodium nitrilotriacetate (NTA) to enhance detergency. Soap-LSDA combinations equal the conventional detergents in every performance respect and undergo biodegradation more readily and completely.     

The mutual solubilization of soap and lime soap dispersing agents

Krafft point measurements were used to show that lime soap dispersing agents (LSDA) and soaps solu-bilize each other. Addition of as little as 5% soap to amphoteric LSDA of limited water solubility (high Krafft point) brought about a substantial lowering of the Krafft point and thus markedly improved water solubility. On the other hand, addition of 10% amphoteric LSDA to sodium palmitate lowered the Krafft point of the soap by 10 to 14 C. Addition of anionic LSDA to sodium palmitate showed smaller Krafft point depressions. Addition of a builder-type salt, such as sodium metasilicate, had essentially no effect on the Krafft points of soap LSDA mixtures.     

Krafft Temperature,Critical Micelle Concentration,and Rheology of “Pseudo-Gemini” Surfactant Comprising Fatty Acid Soap and Bola-Type Quaternary Ammonium Salt

Bola-type quaternary ammonium salt can bridge with two fatty acid soaps through electrostatic attraction to form a pseudogemini surfactant, which enhances the solution viscosity. In this work, the effects of the building blocks (spacer and hydrophobic chain) of a pseudogemini surfactant on the Krafft temperature, critical micelle concentration, and rheological properties were investigated. The results revealed that the addition of bola-type salt obviously decreased the Krafft temperature of sodium stearate (C₁₈ONa), and a bola-type salt bearing a large benzene ring (Bola2be) was more effective than the one bearing an ethyl group (Bola2et) or a hydroxyethyl group (Bola2hy). When bola-type salt is mixed with fatty acid soap at a fixed molar ratio of 1:2, a pseudogemini surfactant forms in situ, and the viscosity of the solution is significantly enhanced by the formation of a worm-like micelle (WLM) network. The stronger the hydrophobicity of the bola-type salt or the tail of the fatty acid soap, the lower the critical overlapping and micelle concentrations, and the stronger is the ability to enhance viscosity. However, pseudogemini surfactants that use sodium stearate as a monomer show similar self-assembly abilities to those using sodium oleate as a monomer. In addition, the WLM formed by pseudogemini surfactants composed of Bola2be and sodium stearate or sodium oleate were liable to branch at high concentrations.     

Synergisms in Binary Mixtures of Anionic and pH‐Insensitive Zwitterionic Surfactants and Their Precipitation Behavior with Calcium Ions

This work aims to investigate synergy in anionic and zwitterionic surfactant mixtures, as they result in better interfacial properties and micellization behavior. Various mixtures of the pH‐insensitive zwitterionic surfactant 3‐(decyldimethylammonio) propanesulfonate (Zwittergent 3–10) and sodium dodecylsulfate (SDS) were prepared in aqueous solution at a range of pH values between 2 and 13. The thermodynamic parameters during mixed surfactant adsorption at the air/water interface are obtained and the results show the mixed surfactant systems having superior properties to the constituent surfactants. Experimentally, the mixed surfactant solutions clearly improve the surface activities by lowering the critical micelle concentration (CMC) and lowering the surface tension at the air/water interface. The synergisms are investigated through the interaction parameters estimated from regular solution theory that is used to quantitatively describe the nonideality of surfactant mixtures. High negative interaction parameters are obtained from these surfactant mixtures. Experimental precipitation phase boundaries of SDS in the presence of CaCl₂ were also investigated in mixtures containing pH‐insensitive zwitterionic surfactant at different pH levels from 2 to 13 and SDS mole fractions of 0.25, 0.50, 0.75, and 1.00. Changes in the precipitation phase boundaries are due to the changes in the speciation or activities of the major components both below and above the CMC. As a result, the precipitation phase boundaries are pH dependent. In addition, mixed micellization and counterion binding to the micelle also change the precipitation phase boundary above the CMC. The activity‐based solubility product of calcium dodecylsulfate is also determined from the precipitation phase boundaries below the CMC. X‐ray diffraction patterns and SEM images confirm that only calcium dodecylsulfate precipitates in the soap scum for all pH and surfactant compositions studied.     

脂肪酸甲酯磺酸盐

脂肪酸甲酯磺酸盐简称(MES)是以天然动植物油脂为原料制得的脂肪酸系阴离子表面活性剂。它具有良好的去污性、钙皂分散性、抗硬水性、乳化性、增溶性和生物降解性,并能改进肥皂的溶解性。由于MES性能优良,主要用于合成洗衣粉、复合皂粉、复合肥皂、香波以及个人清洁用品中。对MES的生产现状、产品形式、性能以及应用进行了概述。     

Modeling of Precipitation Phase Boundaries in Mixed Surfactant Systems Using an Improved Counterion Binding Model

Anionic surfactants, commonly used in household products and the detergency industry, tend to precipitate with divalent counterions in hard water. The unsightly soap scum thus formed also removes the surfactant from the cleaning action. The current research has improved prediction of the precipitation phase boundary for mixtures of surfactants in hard water in two ways: firstly, an accurate value of the solubility product (K _SP ) has been determined for the calcium salt of 4-octylbenzene sulfonate, and accurate temperature dependent K _SP values have been determined for the calcium salts of dodecyl sulfate and decyl sulfate; secondly, improvements in prediction of the precipitation phase boundary have been achieved using an improved model. The K _SP values of the decyl sulfate and dodecyl sulfate salts strongly increase with increasing temperature, with the shorter chain surfactant having significantly higher K _SP than its longer chain analogue. At 30?°C the K _SP of the 4-octylbenzenesulfonate salt is similar to that of the dodecyl sulfate salt, perhaps due to the similarity in the length of their hydrocarbon tails. A recent counterion binding model proposed by our research group and micellization models have been used to model the precipitation phase boundaries for both single anionic surfactant and binary mixed anionic surfactant systems, improving thermodynamic modeling of the precipitation phase boundary of single and binary mixed anionic surfactant systems. In particular, the improved model of counterion binding has allowed the model to predict the phase boundary accurately over a range of temperatures.     

Dissolution Study of Salt of Long Chain Fatty Acids (Soap Scum) in Surfactant Solutions. Part II: Kinetics of Dissolution

A study of the dissolution kinetics of soap scum, calcium octadecanoate (Ca(C₁₈)₂), by aqueous solutions was carried out by measuring the rate of dissolution of Ca(C₁₈)₂ using a flow cell apparatus. These solutions contained three different types of surfactants: dimethyldodecylamine oxide (DDAO), sodium dodecyl sulfate (SDS), or octyl polyglycoside (C₈APG), in the presence of a chelating agent, disodium ethylenediaminetetraacetate (Na₂EDTA). The resulting rate of dissolution corresponds well with the equilibrium solubility obtained in the part I of this series even though the dissolution is rate limited (far from equilibrium). High rates of Ca(C₁₈)₂ dissolution are achieved in solutions of zwitterionic DDAO or nonionic C₈APG with Na₂EDTA at high pH. From rate analysis, the Ca(C₁₈)₂ dissolution was found to be surface-reaction limited rather than limited by solution processes or wettability.     

MES与皂的复配性能

MES是以天然油脂为原料,具有良好的去污性、钙皂分散性、乳化性、增稠性和耐硬水性,以及极低的刺激性、毒性和优良的生物降解性,是安全性高的表面活性剂。进行了MES与皂复配的性能试验,结果表明,MES对皮肤刺激性低,可提高产品的抗硬水性能,避免钙镁皂垢吸附在清洁用具表面。     

表面活性剂复配体系的分析

介绍了一种使用经典的分析技术定量测定液体皂、皂胶、洗衣皂及香皂中存在的皂类、脂肪酸、非离子表面活性剂及除肥皂以外的阴离子表面活性剂和两性表面活性剂混合物的分析方法。这种方法克服了分析混合表面活性剂系统时常常会碰到的问题。     

两性表面活性剂(四)两性表面活性剂的一般性质

介绍了两性表面活性剂的流变性、水溶助长性、钙皂分散性和抗硬水性等一般性质。讨论了两性表面活性剂的流变性与表面活性剂浓度之间的关系,并给出了调节混合体系流变性的方法。从混合胶束理论出发,对两性表面活性剂是比其他类型表面活性剂更优秀的钙皂分散剂这一事实,作者提出了新见解。同时,对两性表面活性剂的生态性质,如生物降解性、鱼毒性等也进行了较为详细的介绍。     

Properties and applications of amphoteric surfactant: A concise review

Amphoteric surfactants have long hydrophobic hydrocarbon chain and hydrophilic positive as well as negative charged center connected with each other by a spacer group. Thus, this type of surfactant maintains overall charged neutrality. The properties of amphoteric surfactants depend primarily on the length of the hydrophobic hydrocarbon chain, the number of methylene segments in the spacer, the positive and negative charged groups, and their relative position. The ionic activity of amphoteric surfactants is influenced according to the pH value of the solvent. They display cationic behavior below the isoelectric points and anionic behavior at a higher pH. They take the shape of zwitterions in the area of the isoelectric point. In fact, amphoteric surfactants can be parted into pH-sensitive and pH-insensitive surfactants. The pH-insensitive surfactants stay as zwitterionic form irrespective of the pH of the solution. This surfactant has some unique features because of its precise molecular structure as follows: high water solubility, high surface activities, a wide isoelectric range, low critical micelle concentration (CMC), high foam stability, low toxicity, low irritating, excellent biodegradability, bioactivity, interface change, and so on. Because of these special characteristics, amphoteric surfactants have been immensely interested in many applications in the scientific community, including cosmetics, chromatography, enhanced oil recovery, electrochemistry, nanoscience, polymer chemistry, and waste water treatment. This review aims to study about amphoteric surfactants, which have only one hydrophobic hydrocarbon tail and two oppositely charged hydrophilic headgroups connected with each other by a spacer group and its properties, applications in various academics and industrial fields.     

无盐咪唑啉两性表面活性剂的合成及性能研究

以丙烯酸及丙烯酸衍生物为原料,采用两步法成功合成出了无机盐含量≤0．06％的无盐咪唑啉。产品外观澄清透明,与阴离子、阳离子和非离子表面活性剂配伍性良好。在硬水中有较好的发泡能力,与同类产品（咪唑啉）相比,刺激性更小,特别适用于婴儿洗浴等产品配方中。     

Soap-based detergent formulations: XIX. Amphoteric alkylsuccinamide derivatives as lime soap dispersants

A series of amphoteric surfactants was synthesized by reaction of 1,3-propanesultone with N-alkyl-N′-(ω,ω-dimethylaminoalkyl)succinamides. The intermediate succinamides were prepared by reacting methyl N-alkylsuccinamates, obtained from alkylamines containing 8 to 18 carbon atoms, with N,N-dimethyl-1,3-propylenediamine or N,N-dimethylethylenediamine neat. The amphoterics were isolated as hygroscopic crystalline solids having superior lime soap dispersing ability, water solubility, and calcium ion stability. Detergency studies at 0.2% concentration (300 ppm water hardness) indicated good washing ability when used alone and excellent performance in combination with soap or in soap-silicate formulations. Presented at the AOCS Meeting, Cincinnati, 1975.     

Surface active agents from isopropenyl esters: Acylation of isethionic acid and N-methyltaurine

Acylation of sodium isethionate with isopropenyl stearate at 200 C for 30 min gave a 95% yield of sodium 2-sulfoethyl stearate, acetone being the only byproduct. Acylation of N-methyltaurine at 200 C for 90 min gave a 95% yield of N-methyl-N-(2-sulfoethyl) stearamide sodium salt. Corresponding surface active derivatives were also prepared from pelargonic, lauric, myristic, palmitic, oleic, phenylstearic and hydrogenated tallow fatty acids from their respective isopropenyl esters. Detergency, foam height, wetting time, lime soap dispersing power, critical micelle concentration and other surfactant properties were evaluated. Optimum properties were found at the C₁₄−C₁₈ fatty acid chain length. Unsaturation or branching increased solubility. The 2-sulfoethyl esters were similar to the N-methyl-N-(2-sulfoethyl) amides in foam height, wetting ability and lime soap dispersing power, superior to the N-methyl-N-(2-sulfoethyl) amides in detergency, but inferior in calcium stability and less stable to acid and alkali. Both compounds are readily biodegraded. The fatty isopropenyl ester synthesis has an advantage in yield and purity of the product and could increase the utilization of the 2-sulfoethyl esters and N-methyl-N-(2-sulfoethyl) amides in many applications. Presented at the ISF-AOCS Meeting in Chicago, September 1970. Deceased. E. Mark. Nutr. Res. Div., ARS, USDA.     

Soap-based detergent formulations: XIV. Amphoteric derivatives of alkylbenzenesulfonamides

Surface active amphoteric derivatives were prepared from alkylbenzenesulfonyl chlorides. Industrial detergent alkylates, as well as benzene and pure 1-phenylalkanes whose side chains ranged from C₁ to C₁₂, were used as starting materials in this study of chemical structure-physical property relationships. The alkylbenzenes were first converted into the corresponding alkylbenzenesulfonyl chlorides with chlorosulfonic acid, and the sulfonyl chlorides were further treated with N,N-dimethyl-1,3-diaminopropane or N,N-bis-(2-hydroxyethyl)-1,3-diaminopropane. The reaction products were quaternized with propanesultone to produce amphoteric surfactants in high yields. The N,N-dimethyl herivatives of pure phenylalkanes were white crystalline powders, whereas the N,N-bis-(2-hydroxyethyl) derivatives were light , lime soap dispersing requirement, surface tension, wetting ability, and calcium ion stability were determined. The commercial detergent alkylate derivatives showed good detergency by themselves as well as in formulations with soap or with soap and silicate builder. Good lime soap dispersing properties were observed with compounds possessing a side chain of at least 4 carbon atoms. Presented at the AOCS Fall Meeting, Philadelphia, September 1974.