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1.
Mixtures of trisiloxane type nonionic silicone surfactant (SS) with sodium dodecylsulfate, tetradecyltrimethylammonium bromide or tert-octylphenol ethoxylated with 9.5 ethylene oxide groups were studied in water at 30 °C by dilute aqueous solution phase diagrams, surface tension and dilute solution viscosity methods. The cloud points for the silicone surfactant aqueous solutions increased upon addition of hydrocarbon surfactants indicating the formation of hydrophilic complexes in mixture solutions. The scrutiny of the surface tension isotherms plotted as a function of SS concentration revealed that competitive adsorption effects are the characteristic features in these mixtures depending upon the SS concentration. Otherwise the isotherms exhibited two break points and the difference of concentration between the two break points increased with the increase in SS concentration indicating the cooperative nature of interactions. The micellar mole fractions of individual surfactants were determined by Rublingh's regular solution theory; interaction parameters and activity coefficients were evaluated and interpreted in terms of synergistic type interactions in these mixtures. The surface active parameters in mixture solutions were estimated and their analysis shows that the molecular species in the mixture solutions have a preferential tendency for adsorption at the air/water interface than in association form in the bulk solution. The effect of hydrocarbon surfactants on the intrinsic viscosity of SS micelles was monitored and related to the enhanced hydration in mixed micelles.  相似文献   

2.
The present work investigates the critical micelle concentration (CMC) of nonionic surfactant solutions using a new approach by monitoring the dirt dispersion (DD) defined as the amount of dirt absorbed by foam using India ink as a model dirt. DD has so far been studied qualitatively by eye estimation. Our quantification studies show that DD increases with increasing surfactant concentration and reaches a maximum. After this, it decreases and becomes very small. The concentration for which DD is maximum corresponds to the CMC, as determined from surface tension measurements. The CMC of natural surfactants obtained from plants Sapindus mukorossi, Albizia procera, Juglans regia, Zephyranthes carinata, and Acacia concinna was determined. The CMC obtained by DD are in reasonably good agreement with those obtained using the surface tension method. The DD method is easy, rapid, and inexpensive and can become an effective tool for estimating the CMC.  相似文献   

3.
Mixed surfactant solutions consisting of cationic/nonionic surfactants were prepared in different compositions of the components in aqueous solution in order to determine the surface properties. The critical micelle concentration (CMC) of aqueous solutions of the individual surfactants cetyl trimethyl ammonium bromide (CTAB) and polysorbate nonionics, and their mixtures are determined at different proportions. The results show that there is synergistic behavior in mixtures at higher mole fraction of nonionic surfactant. The effect of the alkyl chain on the CMC is also determined.  相似文献   

4.
A novel series of six nonionic polymeric surfactants were prepared by polymerization of acrylated poly(ethylene glycol) (PEG, molecular weight MW = 400, 600 and 2,000) and allyl ester of long chain fatty acid chloride (decanoyl and lauroyl chloride). The unique structural features of these surfactants were confirmed by different spectroscopic tools (IR and 1H NMR). The surface properties of these compounds such as surface tension, interfacial tension, emulsion stability, wetting power, foam height, solubilization and dispersant properties in disperse dye systems were determined and evaluated. A comparison study was done between the chemical structures and surface properties of such compounds. Biodegradability and stability to hydrolysis in acidic and alkaline media were also determined and evaluated.  相似文献   

5.
This paper investigated the rheological properties of novel viscoelastic thickening micelle system formed by surfactin and cetyl trimethyl ammonium bromide (CTAB). The total concentration of surfactin and CTAB was maintained at 12 wt%. The rheological behavior of the surfactin/CTAB synergistic micelles with different mass ratio and pH was systematically investigated. For the surfactin/CTAB micellar system with a mass ratio varied from 1/11 to 4/8, the viscosity of the micelles rose to a maximum with increasing pH, and then decreased with a further increase of pH. When the mass ratio was surfactin:CTAB = 2.5:9.5 (pH 5.72), the maximum viscosity of the micelle solution reached 8170 mPa. s. Meanwhile, the viscosity curve of the surfactin/CTAB systems was described by the nonlinear co-rotational Jeffreys model. This work sets a rheological foundation for the application of surfactin/CTAB systems. The thixotropic loop area of the micelles was basically zero. Through viscoelasticity measurements, the results demonstrated that the appropriate surfactin/CTAB mass ratio would favor the stability of the network structure of the synergistic thickening system. The value of G″(viscous modulus) is always higher than the value of G′ (elastic modulus).  相似文献   

6.
A series of cetyl alcohol based anionic bis‐sulfosuccinate gemini surfactants (BSGSCA1,4; BSGSCA1,6 and BSGSCA1,8) with different spacer lengths was prepared using dibromoalkanes. The surfactant structure was elucidated using elemental analysis, Fourier transform infrared spectroscopy (FT‐IR) and nuclear magnetic resonance spectroscopy (NMR). Surface tension measurements were used to determine the critical micelle concentration (CMC), the surface tension at the CMC (γCMC), surface pressure at the CMC (πCMC) and efficiency of adsorption (pC20). On the basis of surface studies, the CMC and γCMC decreases with increasing length of the spacer group. The micelle aggregation number, determined by fluorescence quenching studies, increases with increasing surfactant concentration above the CMC. The micropolarity in the micelle increases with increasing length of the spacer and decreases with increasing surfactant concentration.  相似文献   

7.
To explore how the solvent characteristics influence the self‐aggregation of the cationic gemini surfactant dimethylene‐1,2‐bis(tetradecyldimethylammonium bromide) (14‐2‐14) and to obtain various energetic parameters, conductometric experiments were performed on the binary mixtures in the presence of commonly used organic solvents; formamide (FA), acetonitrile (AN) and 2‐methoxyethanol (ME) in aqueous solutions at varying temperatures (298.15–323.15 K) and compositions. The procedure suggested by Carpena et al. has been utilized to analyze conductivity–concentration plots in order to obtain critical micelle concentration (CMC) and degree of counterion dissociation (α) of the micelles. This method provides more accurate results as compared to conventional treatments, and the experimental error for the evaluation of micellar parameters is reduced significantly. The results revealed that, although the process of micellization becomes less favorable with the increase in composition of FA, AN and ME in mixed systems, the increase in CMC at compositions lower than 20% (v/v) of the organic solvents is relatively less, indicating that water character is dominant in the bulk phase. As the enthalpy of micellization became more negative, the corresponding entropy change became less positive and enthalpy–entropy compensation phenomenon has been observed for 14‐2‐14 in all the mixtures within the studied temperature range.  相似文献   

8.
This paper presents a new method for the determination of the critical micelle concentration (CMC) of surfactants in water at elevated temperatures using headspace gas chromatography (HS‐GC). A volatile compound (e.g., toluene) was spiked into the studied solution. At a given temperature, the concentration of volatile species in the vapor phase (measured by HS‐GC) is proportional to the surfactant concentration in the liquid phase in a closed vial. This tendency will change after the solution is saturated with surfactant. By plotting the GC signal of the vapor species vs the concentration of the surfactant concentration in the solution, a breakpoint, i.e., corresponding to the CMC of the surfactant. The present method has good precision (RSD < 10%) and good accuracy. It is also very simple and can be used as an automated method for determining the critical micelle concentration of surfactants at the temperature of interest.  相似文献   

9.
Surface properties of the dodecyl isothiouronium cationic surfactant in a mixed solvent of water and polyethylene glycol of different molecular weights varied from ethylene glycol to polyethylene glycol-600 were determined using surface tension and conductivity measurements. The results showed an increase in the surface properties including critical micelle concentration, effectiveness and efficiency, compared to the surfactant in pure water as the solvent. The interaction between the cationic surfactant and the glycols was described and the molecular weight of the different glycols was rationalized.  相似文献   

10.
A series of carboxylate gemini surfactants, which contain two hydrocarbon chains linked by amide groups, two carboxylate groups, a flexible alkane spacer were synthesized by three-step reactions and named alkylidene–bis-(N,N′-dodecyl-carboxypropylamides) (2C12H25CnAm; n = 2, 3, 4, 6, 8 is the number of methylene groups of the spacer), their structures were confirmed by FTIR,1H NMR, and LC–MS/TOF, and their purity checked by HPLC. The micellar properties with increasing spacer chain length of these gemini surfactants were determined by surface tension methods. The critical micelle concentration (CMC) varies slightly with spacer chain length; surface tension at CMC(γCMC), the tendency of micellization versus adsorption, CMC/C20, the minimum area per surfactant molecule at the air/solution interface (ACMC), all decrease with increasing spacer chain length; surface reduction efficiency, pC20, the surface excess at the air/solution interface (ГCMC) increase with increasing spacer chain length. The results probably indicate that increasing spacer chain length of these carboxylate gemini surfactants will increase spacer incorporation into the double hydrophobic chain.  相似文献   

11.
朱海林  胡志勇  王建龙  曹端林 《精细化工》2013,30(12):1374-1378
以长碳链溴代烷、N,N-二甲基乙醇胺和对二溴苄为原料,合成了3种不同疏水链长的烷基二苄醚双季铵盐Gemini表面活性剂(10-B-10,12-B-12,14-B-14),采用FTIR、1HNMR和ESI-MS对其结构进行了表征。采用稳态荧光法测定了3种表面活性剂的临界胶束浓度(CMC)和胶束聚集数。结果表明,采用荧光法测定的CMC与表面张力法所得的值基本一致,随着疏水链长从10增加至14,CMC从3.24 mmol/L降至0.056 mmol/L。采用外推法得到3种表面活性剂的临界胶束聚集数(N m)分别为6.98(10-B-10),3.87(12-B-12)和1.62(14-B-14)。动态光散射结果表明,该类表面活性剂在CMC以上易生成囊泡,盐的加入会诱导囊泡转变成胶束。  相似文献   

12.
Mixed micellization of cationic gemini surfactant butanediyl-1,4-bis(dimethyldodecylammonium bromide) with nonionic surfactants (sorbitan esters, alcohols and phenol ethoxylates) and triblock copolymers has been studied tensiometrically. Various physicochemical parameters of the studied systems including ideal CMC values, experimental and ideal micellar compositions, interaction parameters, activity coefficients of the components, etc. have been evaluated by considering theoretical models of Clint, Rubingh, Rosen and Maeda. The experimental critical micelle concentration (CMC) values of the mixed micelles were lower than the CMC values of the individual components and showed a negative deviation from ideal CMC (CMC*) values. The analysis reveals that the mole fractions of gemini are lower compared to the nonionic surfactants/triblock polymers and the values of ΔG m ° , ΔG ad ° , G min and ΔG ex m show that the spontaneity of the studied mixed micelles relatively decreases as the content of the gemini in the bulk phase increases.  相似文献   

13.
In this article, we report intermolecular interactions in terms of the effect of benzfused heterocyclic compounds, i.e., 2-thioureidobenzimidazole and 2-thioureidobenzoxazole (0.00, 0.01, and 0.05 mol kg−1), on the micellization behavior of sodium dodecylsulphate (SDS) (1–52 mmol kg−1) in dimethylsulphoxide (DMSO) at different temperatures (293.15–313.15 K) through conductometric and spectroscopic investigations. The variation of specific conductance with SDS concentration has been utilized to estimate the critical micelle concentration ( CMC). The above-performed techniques infer that the presence of additives results in a decrease in the CMC values. Various standard thermodynamic parameters such as free energy change (), enthalpy change (), and entropy change () of micellization have been determined using the temperature dependence of CMC. The above calculated parameters and also UV–visible and fluorescence spectroscopy have been used to obtain information regarding the various interactions between the compounds and surfactant aggregates. In addition, an attempt has also been made to examine the minimum inhibitory concentration (MIC) of the heterocompounds, which indicates the effectiveness of these compounds against fungus growth at a particular concentration. These synthetic heterocyclic compounds find increasing applications in material science, medicinal chemistry, and biochemistry due to their antifungal and antioxidant properties.  相似文献   

14.
以α-溴代十四酸乙酯和4-癸基苯酚为原料,经Williamson醚化、磺化及皂化反应制备了一种不对称阴离子Gemini表面活性剂α-(4-癸基-2-磺基)-苯氧基十四酸钠,简写为C12CO2Na-p-C10SO3Na,考察了醚化反应条件,并用FTIR和1HNMR表征了中间体及目标产物结构。结果表明,醚化反应的最佳条件为:以N,N-二甲基甲酰胺(DMF)和甲苯作溶剂,无水K2CO3作缚酸剂,物料比n(α-溴代十四酸乙酯)∶n(4-癸基苯酚)=1.05∶1,回流反应3 h,醚化产物收率为77.2%(以4-癸基苯酚计)。采用吊片法测定了目标产物的表面活性,其表面张力最低可降至26 mN/m左右,临界胶束浓度(CMC)为3.28×10-6mol/L,比相应常规单链表面活性剂十四烷酸钠和间癸基苯磺酸钠的CMC低3个数量级,体现出Gemini表面活性剂优异的表面活性。  相似文献   

15.
Micellar and interfacial properties of mixed surfactant systems comprising benzalkonium chloride, a cationic surfactant and nonionic polyoxyethylene alkyl ether surfactants (POE: C10E7, C10E8, C10E9, C10E10) have been investigated by surface tension, fluorescence and dynamic light scattering techniques. Critical micelle concentration (CMC) for different mixing mole fractions has been investigated by surface tension and fluorescence measurements. Ideal CMC, mixed micellar composition (X 1 m , X 1 σ ), interaction parameters for mixed micelles (β m) and adsorption monolayer (β σ ), surface excess concentration (Гmax), minimum area per molecule (A min) and related thermodynamic properties have also been determined. Lowering of the CMC and negative interaction parameter values indicate synergism in the mixed micelle and monolayer formed, whereas, thermodynamic parameters evaluated for the proposed mixed systems indicate stability of the resulting micelles and monolayer. Micellar aggregation number (N agg) and hydrodynamic diameter (D h) computed from fluorescence and dynamic light scattering measurements respectively illustrate micellar growth in the mixed state. Results obtained for the proposed mixed systems can be helpful in designing smart materials for industrial surfactant based formulations.  相似文献   

16.
The surface properties of 5 extended surfactant C12–14P mE2S solutions in pure water and 0.1 M NaCl were investigated through surface tension and electrical conductivity measurements. The surface properties measured include the critical micelle concentration (CMC), critical surface tension (γcmc), maximum surface excess concentration (Γmax), minimum area occupied per surfactant molecule (Amin), and efficiency in surface tension reduction (pC20). The CMC values of the 5 surfactants decreased with increasing polypropylene oxide number (PON) and were higher than those obtained in 0.1 M NaCl. The Γmax values showed a downward trend whereas the Amin values exhibited an upward trend with increasing PON without NaCl. The Γmax values were higher and the Amin values were lower than those obtained without 0.1 M NaCl. The CMC values increased at elevated temperatures. The CMC values of C12–14P3E2S, C12–14P5E2S, and C12–14P8E2S were similar but were markedly lower than those of C12–14E2S at different temperatures. When PON was less than 12, the log CMC value decreased linearly with increasing PON in the absence of salt, and the relationship between pC20 and PON was linear. But in the presence of 0.1 M NaCl, the log CMC value decreased exponentially with increasing PON.  相似文献   

17.
Surfactant solutions are commonly used for the remediation of petroleum-contaminated soil due to their good petroleum removal performance, time-saving capability, and cost effectiveness. However, applying surfactants in excess concentrations could make oil recovery difficult. Moreover, residual surfactants in soil are toxic to microorganisms and plants. Thus, it is crucial to identify a suitable surfactant concentration for soil washing applications. The main objective of this study was to evaluate the effect of soil minerals (quartz and kaolin) and organic matter (OM) on the critical micelle concentration (CMC) of polyethoxylated sorbitan ester surfactants (Tween 20, 40, 60, and 80) and its effect on diesel removal from diesel-contaminated soil by soil washing. The results showed that Tween surfactants with shorter carbon chain lengths required higher CMC for diesel removal from quartz, while those with longer chains needed higher CMC for kaolin cleanup. FTIR results illustrated that oxygenated functional groups of Tween surfactants played an important role in their adsorption on quartz, while alkyl chains of Tween surfactants were responsible for their adsorption on kaolin. At a certain OM concentration, quartz and OM exhibited antagonistic effects, resulting in CMC reduction. In soil washing application, maximum diesel removal could be achieved from kaolin, in the presence of which surfactants exhibited the highest CMC. Based on FTIR results, the adsorbed surfactant could reduce the hydrophobicity of the kaolin surface, thus preventing the re-deposition of detached diesel.  相似文献   

18.
19.
Three fluorinated cationic surfactants were prepared by condensing N-(2-bromoethyl)perfluoroalkylamides with stoichiometric amounts of pyridine, triethanolamine, and triethylamine to produce three quaternary ammonium salts. The surface and biocidal properties of these surfactants were investigated to find the relation between the structure of the hydrophilic portion of the compounds and their efficiency as biocides. The properties studied included critical micelle concentration (CMC), effectiveness (IICMC), surface excess concentration (Tmax), and area occupied by a molecule (Amin). Free energies of micellization (ΔG mic o) and adsorption (ΔG ads o) of the surfactants in aqueous solution were calculated. The minimal inhibitory concentrations of the prepared compounds were tested against five strains as representative group of microorganisms.  相似文献   

20.
杨锐  杨春花  王力峰  梁斌 《广州化工》2014,(12):116-118
采用电导法及表面张力法分别测定了十二烷基硫酸钠(阴离子表面活性剂)和十二烷基三甲基氯化铵(阳离子表面活性剂)的临界胶束浓度,两种实验方法测得十二烷基硫酸钠的临界胶束浓度约为7.0×10-3mol·dm-3,十二烷基三甲基氯化铵的临界胶束浓度约为1.60×10-2mol·dm-3,两种方法所得结果一致。  相似文献   

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