A colorimetric method for the determination of parts/million of nonionic surfactants

A method for the determination of nonionics in low concn (0–20 ppm) has been developed. This method is based on the formation of a blue complex between ammonium cobaltothiocyanate reagent and a polyethoxylated compound. This complex is extracted into benzene from a saturated salt solution and measured with a spectrophotometer at 320 mμ. The absorbance reading is compared to a standard. The method requires only a single extraction and no preliminary concn step is necessary. It is sensitive to polyethoxylated compounds containing three or more moles of ethylene oxide. We have used this method to detect as little as 0.01 mg of nonionic in 100 ml of sample (0.1 ppm). Reaction conditions, sensitivity differences between compounds, interferences and suitability for use in biodegradation studies have been investigated. The accuracy and repeatability of this method is ±3% relative at 20 ppm concn.     

Solubilisation of water in alkanes using nonionic surfactants

Nonionic surfactants are frequently used as emulsifiers in nonpolar oil + water systems and as solubilisation agents for oil in water, or vice versa. In the latter application the amount of, say, water that can be solubilised in nonpolar oil (to give microemulsion droplets) depends on: (a) the capacity of the micelles to incorporate water; and (b) the fraction of surfactant originally present as micelles. This paper is concerned with the single-phase water-in-oil (W/O) microemulsion regions enclosed by the haze and solubilisation boundaries at the oil-rich end of Shinoda-type phase diagrams. The systems studied contain the nonionic surfactant C₁₂H₂₅(OCH₂CH₂)₅OH (C₁₂E₅), normal alkane (heptane, decane or tetradecane) and water. Critical microemulsion concentrations (cμc) and droplet compositions for w/o microemulsions formed from C₁₂E₅ in alkane have been determined at phase boundaries over a range of temperatures. The results show how the maximum extent of water solubilisation is determined jointly by the cμc and the maximum droplet size for a given temperature. It appears that for larger (microemulsion) droplets, the cμc is determined by temperature rather than by droplet size. However, along part of the haze curves, aggregates form with only small amounts of water (less than four molecules per ethyleneoxy group on the surfactant head groups). For a given temperature, in the small range where either micelles or microemulsion droplets can exist, reverse hydrated micelles have much higher critical micelle concentrations (cmc) than the cμc of the larger microemulsion droplets.     

Application of NMR for the determination of HLB values of nonionic surfactants

Hydrophilic lipophilic balance (HLB) values for various commercial nonionic surfactants have been determined by means of high resolution NMR. The results are in good agreement with given HLB values. The method is rapid, nondestructive and requires only small samples.     

The characterization of nonionic surfactants by NMR

The methods currently reported in the literature for the characterization of nonionic surfactants are usually applied to one portion of the molecule and require a knowledge of the other portion for complete identification. This indirect approach leaves much to be desired. A simple, rapid, and more direct method of characterization is to measure the proton signal intensity in high resolution nuclear magnetic resonance (NMR) spectra. This method determines the hydrophile to hydrophobe ratio without requiring standard samples for calibration or a prior knowledge of the hydrophobe. In addition, this method will frequently give much valuable information about the identity of the hydrophobe, such as the average chain length, the degree of branching, and the type of aromatic substitution, if any. This method has been applied to the characterization of the common types of commercial polyethylene oxide condensates. The application of NMR to the analysis of formulated detergent products is also discussed. Presented at the AOCS meeting in New Orleans, La., 1962.     

可分解香兰素基非离子表面活性剂的乳化性

针对已合成的含缩醛结构的环保型非离子表面活性剂香兰素辛二醇缩醛聚氧乙烯醚(VAEO),研究不同乙氧基链长的VAEO_n(n=6～24)的表面活性及乳化性,并与壬基酚聚氧乙烯醚(NPEO_(10))的表面活性及乳化性作比较。结果表明,随EO聚合度(n)增大,VAEO_n降低表面张力和油/水界面张力的能力下降,对石蜡乳化能力减弱。EO聚合度为6～10的VAEO_n与NPEO_(10)降低表面张力的能力相近,乳化性能也相当。VAEO_n降低油/水界面张力的能力较NPEO_(10)差。采用Material Studio软件模拟分析VAEO_n和NPEO_(10)乳化石蜡的能力,结果表明VAEO_n乙氧基链越长,乳化石蜡重新聚集的速度越快,即乳化性能越差,模拟结果与乳化石蜡分相法的实验结果相吻合。     

The status of biodegradability testing of nonionic surfactants

A wide range of nonionic surfactants was studied in an extensive inter-laboratory biodegradability testing program carried out by member companies of The Soap and Detergent Association over a three year period. The objectives were to determine the biodegradability of a variety of nonionic surfactants, and to develop a reliable laboratory scale test method which could be used to evaluate the biodegradability of new candidate materials. The results of this research and testing confirm that the primary and secondary alcohol ethoxylates, the alkyl alkanolamides, and the alkyl amine oxides are all highly biodegradable. These materials represent the important classes of nonionics used in household and institutional synthetic detergents. The removal of these materials under conditions of normal secondary wastewater treatment can be anticipated. The diversity of structures represented in the complete nonionic surfactant spectrum, and the problems of residue analysis imposed serious obstacles in the development of a single standard laboratory procedure which will correlate well with the limited field data presently available. The objective of establishing a standard test for all nonionics was not achieved. Residues of nonionic surfactants from household and institutional synthetic detergents do not appear to contribute to esthetic water pollution or to interfere with waste treatment processes. A variety of biodegradability assessment procedures, applicable to specific nonionics or nonionic groups are currently available and should assure that their residues will not adversely affect the quality of receiving waters. The Subcommittee plans to maintain a program for continued research in nonionic biodegradability testing. Prepared under the auspices of The Subcommittee on Biodegradation Test Methods of The Soap and Detergent Association.     

Quantitative determination of polyethylene glycols in nonionic surfactants by high pressure liquid chromatography

A method employing high pressure liquid chromatography has been developed for the quantitative determination of polyethylene glycols in ethoxylated fatty alcohols and alkylphenols. This technique overcomes many of the limitations encountered in previously-reported methods. The polyethylene glycols are separated from the ethoxylated product and other sample components using a 65/35 acetonitrile/water mobile phase and a Bondapak C₁₈/Corasil reversephase column system. The response factor of the differential refractometer detector is determined using Carbowax standards of appropriate molecular weights. The molecular weight of the polyethylene glycols in each sample is approximated using thin layer chromatography prior to the high pressure liquid chromatography calibration and analysis. The precision of this method for the determination of polyethylene glycols is ± 4% relative or better, and the recovery of added polyethylene glycols is quantitative. Application of this method to a wide variety of commercial ethoxylated fatty alcohols and alkylphenols is presented. Presented at the Meeting of the American Oil Chemists’ Society, April 1976, New Orleans.     

Synthesis of surfactants with Narrow-range distribution of the polyoxyethylene chain

Ethoxylation of alcohols, alkylphenols, and alkylamines has been studied in the presence of a few catalytic systems. Distribution constants were computed. Broad-range distributed ethoxylates are formed in the presence of NaOH, and the distribution constants increase up to the homologue containing six oxyethylene units. Narrow-range distributed ethoxylates are formed in the presence of calcium-based catalysts. It is reflected in the values of the distribution constants because an increase with the growing number of oxyethylene units in successive homologue is not observed.     

The crystallization behavior of calcium carbonate in ethanol/water solution containing mixed nonionic/anionic surfactants

Crystallization of CaCO₃ was performed in an ethanol/water solution containing Pluronic F127 (EO₉₇PO₆₈EO₉₇) and sodium dodecyl sulfate (SDS). The effects of the ethanol/water volume ratio, concentration of surfactants, and aging temperature (30-90 °C) on the morphology and polymorphs of CaCO₃ were investigated using scanning electron microscopy (SEM) and powder X-ray diffraction (XRD). The presence of both F127 and SDS in solution favored the vaterite phase of CaCO₃. A binary calcite-vaterite mixture and a ternary calcite-vaterite-aragonite mixture were produced at low (< 60 °C) and high temperatures, respectively. Spherical, plate-like, flower-like, and rod-like crystals were obtained at different ethanol/water volume ratios. Controllable synthesis of nearly pure flower-like vaterite and rod-like aragonite can be realized by adjusting the ethanol/water volume ratio. The formation mechanism of flower-like CaCO₃ crystals is discussed.     

Forecasting the cloud point of alkoxylated nonionic surfactants

The highest effectiveness of detergency for nonionic surfactants is observed in the proximity of the cloud point. This phenomenon is primarily influenced by surfactant molecular structure, such as carbon chain length and type of the hydrophilic components. Target of this investigation is to identify a relationship between the cloud point and the structure of nonionic surfactants based on ethoxylated (C_nE_m), ethoxylated-propoxylated (C_nE_mP_p) and propoxylated-ethoxylated (C_nP_pE_m) fatty alcohols. Three hundred and fifty nonionic surfactants have been prepared for this purpose. These surfactants differ in the C-chain lengths, C₄/C₆ to C₂₀/C₂₂, and the amount of ethylene oxide (EO range [n] 2–22 ethoxylation) and propylene oxide (PO range [p] 0–12 propoxylation) moieties. Mapping the differences in the performance allows us to propose a high-accuracy topological model describing the structure influence on the cloud point.     

非离子型Gemini表面活性剂的性质

Gemini表面活性剂具有的优良表面活性,使之有望作为三次采油用的表面活性剂。用界面张力仪及HAAKERS600流变仪研究了非离子型Gemini表面活性剂的表面活性及流变特性。结果表明,25℃下,氧乙基数(EO数)分别为8,10,12的3种非离子型Gemini表面活性剂8-NP-8、10-NP-10及12-NP-12的临界胶束浓度(cmc)值分别为:0.99,0.15和0.032 mmol/L;非离子型Gemini表面活性剂的表面活性及cmc值受电解质的影响较小;氧乙基数为12的非离子型Gemini表面活性剂可以使亲水及亲油固体表面的接触角明显降低,水润湿性增强;非离子型Gemini表面活性剂溶液的粘度随剪切速率增加基本保持不变,呈现出牛顿流体的特性。     

Analysis of nonionic surfactants in bench-scale biotreater samples

The effluents and activated sludges used in benchscale biotreater units have been analyzed for nonionic alcohol ethoxylates and their residues. Separate bench-scale units were fed linear alcohol ethoxylates (AE), highly branched and branched nonylphenol ethoxylates. Effluents and sludges were first pretreated by a foam sublation technique to provide a gross separation of surfactants from the environmental matrix. This step was followed by normal-phase high-performance liquid chromatography (HPLC) with either fluorescence detection (FD) or evaporative light-scattering detection (ESLD). The AEs were derivatized with phenylisocyanate and analyzed by normal-phase HPLC coupled with FD. At extremely low surfactant levels, pretreatment of large sample volumes resulted in interferences on derivatization. Hence, a normal-phase HPLC method with ELSD was developed. Although some interferences do appear using ELSD, this method appears to be a more viable alternative to derivatization/FD for very low levels of AE. HPLC with FD and ELSD detection methods are more quantitative and provide information on the polyoxyethylene chain than is possible with traditional methods like cobalt-thiocyanate active substance. Presented at the 82nd AOCS Annual Meeting & Expo, May 1991, Chicago, Illinois.     

非离子表面活性剂在制革工业中的应用

简要介绍了非离子表面活性剂的分类,较详细地叙述了常用非离子表面活性剂的乳化性能、润湿性能和配伍性能等相关性能,综述了非离子表面活性剂在制革工业准备工序、鞣制工序以及整饰工序中的作用与功能。     

Use of low-temperature differential scanning calorimetry for determination of ethylene oxide content in some nonionic surfactants

Low-temperature differential scanning calorimetry studies on ethoxylates of hydrogenated castor oil and 12-hydroxystearic acid show endothermic transformations that could be ascribed to melting of ethylene oxide (EO) components of the surfactant molecule. The ethoxylation process also results in formation of free polyethylene glycol (PEG). Separation of free PEG followed by area under the curve measurements enabled estimation of EO content of the product formed during manufacture. The melting endotherm provided additional information on the chain-length distribution of polyoxyethylene units in the surfactant.     

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.     

Study of the efficiency of technical grade nonionic surfactants

Parameters concerning the microemulsion phase behavior of nonionic surfactants of the alkyl polyglycol ether type have extensively been investigated in the last years. By studying these, essential parameters for future applications can be determined. Especially in the field of enhanced oil recovery, lubricants, and cosmetic applications these parameters are of special interest. In this work, the influence of technical grade nonionic surfactants on the phase behavior and the resulting surfactant efficiency has been studied. For this, the alkyl chain length, the degree, type, and order of alkoxylation of the surfactant have been varied. The investigation of these parameters has been conducted by measuring the phase behavior via the Kahlweit fish diagram. It has been found that varying the C-chain length has a great impact on the efficiency, whereas the influence of the ethoxylation degree is minor. By the introduction of propylene oxide, the efficiency has been improved significantly. Additionally, it is important to have the right order of alkoxylation. If the fatty alcohol is first ethoxylated and afterwards propoxylated the efficiency is significantly decreased.     

Phase diagrams of water and sodium dodecyl sulfate combined with four commercial nonionic surfactants

Phase diagrams in which water was combined with sodium dodecyl sulfate, plus one of four nonionic surfactants, as well as an aliphatic oil, were determined by visual observation and low-angle X-ray diffractometry. The results agreed with earlier investigations on specially synthesized polyethyleneglycol alkyl ether surfactants, except that the extended water-in-oil microemulsion areas were not found with the commercial surfactants.     

香兰素基非离子表面活性剂的动态表面张力与气/液界面吸附行为

通过最大气泡压力法测定香兰素基聚氧乙烯醚(VAEO)的动态表面张力,利用Word-Tordai方程研究其在气/液界面的吸附行为。结果表明,质量浓度低于临界胶束浓度(cmc)时,VAEO在吸附前期为扩散控制吸附,在吸附后期为混合动力控制吸附;质量浓度大于cmc时,为混合动力控制吸附,胶束不影响吸附行为。VAEO_(10)和VAEO_(20)的扩散系数D的数量级为10~(-11)m~2/s,比文献报道的壬基酚聚氧乙烯醚(NPEO_9)低一个数量级。