Surface properties of linear alkyl benzene sulfonates in hard river water

Surface properties of a series of highly purified linear alkyl benzene sulfonates were extensively studied in hard river water. The effects of water hardness, alkyl chain length and position of the phenyl sulfonate group in the molecule on such surface properties as pC₂₀, critical micelle concentration (CMC), γ_CMC, CMC/C₂₀ ratio, and minimum area per molecule at the interface are discussed in detail. The position of phenyl sulfonate group in the molecule was found to have a pronounced effect on the CMC, γ_CMC value, CMC/C₂₀ ratio, and, to the contrary, a relatively small effect on the pC₂₀ value. The linear relationship between pC₂₀ or-log CMC, and m, the number of carbon atoms in the alkyl chain, was found for surfactants with the phenyl sulfonate group either at the terminal position or at the more central position in the molecule. γ_CMC decreases but the CMC value increases, when the position of phenyl sulfonate group moves from the terminal toward a more central position of the molecule, reflecting the “Hartley Effect” resulting from the branched alkyl chain.     

Synthesis and Self-Aggregation of a Hydroxyl-Functionalized Imidazolium-Based Ionic Liquid Surfactant in Aqueous Solution

This paper deals with the synthesis and self-aggregation of a hydroxyl-functionalized imidazolium-based ionic liquid (IL) surfactant, namely 1-hydroxyethyl-3-dodecylimidazolium chloride ([C₂OHC₁₂im]Cl). The molecular structure was confirmed by means of electrospray ionization mass spectrometry (ESI–MS), ¹H nuclear magnetic resonance (¹H NMR) and elemental analysis. Many important physicochemical parameters, such as the critical micelle concentration (CMC), the surface tension at CMC (γ_CMC), the adsorption efficiency (pC ₂₀), the surface pressure at CMC (Π_CMC), the maximum surface excess (Γ _m ), the minimum molecular cross-sectional area (A _min), the value of CMC/C ₂₀, the average number of aggregation (N _m ) and the micellar microenvironment polarity were determined by surface tension-concentration curves, fluorescence spectra, and electrical conductivity. The phenomena of the second CMC, the concentration dependence of N _m , and the critical average aggregation number (N _m,c) of imidazolium-based IL surfactants are reported for the first time in this paper.     

A Novel Zwitterionic Imidazolium-Based Ionic Liquid Surfactant: 1-Carboxymethyl-3-Dodecylimidazolium Inner Salt

A novel zwitterionic imidazolium-based ionic liquid (IL) surfactant, 1-carboxymethyl-3-dodecylimidazolium inner salt, was synthesized. The molecule structure was confirmed by means of electrospray ionization mass spectrometry, ¹H nuclear magnetic resonance and elemental analysis. The isoelectric point (pI) is 3.8 ± 0.1 at 35 ± 0.1 °C. The other important physicochemical parameters such as the critical micelle concentration (CMC), the surface tension at CMC (γ_CMC), the adsorption efficiency (pC ₂₀), the surface pressure at CMC (Π_CMC), the maximum surface excess (Γ_m), the minimum molecular cross-sectional area (A _min), the value of CMC/C ₂₀ and the average number of aggregation (N _m) were determined by surface tension and steady-state fluorescence probe methods, respectively.     

Polymeric surfactants for enhanced oil recovery. Part V: Prediction models for the effect of temperature and length of polyoxyethylene chain or hlb on surface and thermodynamic properties of some ethoxylated polymeric nonionics

Several equation models were investigated to find the relationship between temperature (T). number of ethylene oxide (EO) units (n) or the hydrophile-lipophile balance (HLB) and the surface and thermodynamic properties of some ethoxylated alkylphenol-formaldehyde polymeric nonionic surfactants. These properties include critical micelle concentration (CMC), free energy of micellization (ΔG_mic), surface tension at CMC (7_CMC), effectiveness (γ_CMC) and efficiency (pC₂₀) of surfactant to reduce the surface tension of water. The values of the ratio CMC/C_{2(π = 20)} were also considered. The linear multiple regression technique was employed to determine the parameters of the equations and to choose the best forms with the highest values of R² and F-ratio which reflect the goodness and the reliability of the fit.     

Surface properties of N-alkanoyl-N-methyl glucamines and related materials

The surface properties [effectiveness of surface tension reduction (γ_CMC) critical micelle concentration (CMC), efficiency of surface tension reduction (pC ₂₀), maximal surface excess concentration (Γ_max), minimal area/molecule at the interface (A _min), and the (CMC/C ₂₀) ratio] of some well-purified N-alkanoyl-N-methyl glucamines and related polyol-based N-methyl amide-type surfactants, having the structural formula RC(O)N(Me)CH₂(CHOH)_xCH₂OH, where RC(O)=undecanoyl, lauroyl, tridecanoyl, myristoyl, and x=1,3, and 4, were investigated at 25°C in distilled water and 0.1 M NaCl. Water solubility of these compounds does not simply depend on the number of hydroxyl groups in the molecule but is associated with the balance between intermolecular hydrogen bonds and hydrogen bonds formed with water molecules. The fundamental interfacial properties, such as CMC and γ_CMC and two thermodynamic parameters, standard free energy of adsorption and standard free energy of micellization, were found to be significantly dependent on the hydrophobic acyl chain rather than on the number of CHOH groups in the hydrophilic moieties. By contrast, the practical performance properties were greatly dependent on the nature of the hydrophilic group. As a whole, these surfactants had desirable foaming properties and efficient wetting abilities. Furthermore, synergism in foaming and wetting abilities was observed in a binary mixture of these surfactants with an alkyloxyethylene sulfate.     

Synthesis and Surface Properties of Novel Carboxylic Ester-Containing Imidazolium-Based Zwitterionic Surfactants: Monoalkyl 2-(3-Methylimidazolium-1-yl) Succinate Inner Salts

A series of carboxylic ester‐containing imidazolium‐based zwitterionic surfactants, namely, monoalkyl 2‐(3‐methylimidazolium‐1‐yl) succinate inner salts (C_nMimSU, n = 8, 10, 12 and 14), have been synthesized. Their structures were confirmed by ¹H NMR, ¹³C NMR and FTIR. The typical physicochemical properties parameters such as isoelectric point, critical micelle concentration (CMC), surface tension at CMC (γ_CMC), surface pressure at CMC (Π_CMC), adsorption efficiency (pC₂₀), the maximum surface excess (Γ_m), the minimum molecular cross‐sectional area (A_min) and the value of CMC/C₂₀ were determined. The effect of the long‐chain length on the important physicochemical properties of C_nMimSU was studied. It is found that the surface activity of C_nMimSU is enhanced with the long‐chain length increases.     

Surface tension of bovine serum albumin and tween 20 at the air-aqueous interface

Interfacial properties (surface tension, σ, and critical micelle concentration, CMC) of aqueous solutions of Tween 20 (polyoxyethylene sorbitan monolaurate) and/or bovine serum albumin (BSA) were evaluated. Temperature, Tween 20 concentration in the aqueous phase, BSA/Tween 20 ratio, and aqueous phase composition [water, ethanol (0.5, 1.0, and 2.5 M), and sucrose (0.5 M)] were the variables studied. The CMC of Tween 20 was determined by surface tension measurements (Wilhelmy plate method). The existence of BSA-Tween 20 interactions was deduced from surface tension measurements. The results show that the effect of temperature on CMC depends on the aqueous phase composition, but the σ value at CMC, σ_CMC, does decrease as temperature is increased. The CMC and σ_CMC values also depend on the aqueous phase composition. In aqueous ethanol solutions, the CMC increases, but σ_CMC decreases. However, in sucrose aqueous solutions, the CMC decreases, but there is no significant effect on σ_CMC. The BSA-Tween 20 interactions at the interface depend on both Tween 20 concentration (C) and solute in the bulk phase. In water and aqueous solutions of ethanol and sucrose, σ values decrease in the presence of protein at C<CMC but are practically independent of C at C>CMC. This is an indication that the interfacial characteristics of the mixed film are determined by either the protein or the lipid at the higher and lower protein/lipid ratio, respectively. In the intermediate region, the existence of BSA-Tween 20 interactions dominates the interfacial characteristics of mixed films.     

Surface activity and premicellar aggregation of some novel diquaternary gemini surfactants

A series of novel cationic gemini surfactants, C _n H _2n+1 N⁺(CH₃)₂CH₂CHOHCHOHCH₂N⁺(CH₃)₂C _n H _2n+1 ·2Br⁻, have been synthesized, and their surface properties were investigated in water, 0.1 N NaCl, and 0.1 N NaBr at 25°C. From surface tension-log molar concentration plots, the pC₂₀, critical micelle concentration (CMC), and γ_CMC values have been determined, and the area/molecule at the aqueous solution/air interface was calculated. When the number of carbon atoms in the alkyl (hydrophobic) chains is above a certain number, which depends upon the molecular environment, the surface activity of the compounds is less than expected. This appears to be due to formation of small, soluble aggregates below the CMC. Equilibrium constants calculated for this aggregation indicate that a series of oligomers are formed.     

Synthesis,characterization, and surface properties of phenylalanine-glycerol ether surfactants

A novel homologous series of 1-N-l-phenylalanine-glycerol ether surfactants was synthesized in satisfactory yields via reaction of epichlorohydrin with aliphatic alcohols with alkyl chains of 10–15 carbon atoms. Structural assignment of the new compounds was made on the basis of elemental analysis and spectroscopic data. Critical micelle concentration (CMC), surface tension at the CMC (γ_CMC), surfactant concentration required to reduce the surface tension of the solvent by 20 mN/m (pC₂₀), and the interfacial area occupied by the surfactant molecules (A_min) were determined from aqueous surface tension measurements using the Wilhelmy plate technique.     

Aggregation Behavior of Surface Active Dialkylimidazolium Ionic Liquids [C12C n im]Br (n = 1–4) in Aqueous Solutions

Four diakylimidazolium ionic liquids, namely 1-alkyl-3-dodecylimidazolium bromides ([C₁₂C _n im]Br) with the same dodecyl long-chain tail (C₁₂) and the short alkyl side chain (C _n , n = 1–4), were synthesized, and their molecule structures were confirmed by ESI–MS, ¹H-NMR and elemental analysis. The physicochemical properties of [C₁₂C _n im]Br (n = 1–4) were determined by means of surface tension and fluorescence probe methods, respectively. It was found that elongation of the side chain length will bring about an enhancement of surface activity. Along with the side chain length increasing, the critical micelle concentration (CMC), surface tension at CMC (γ _CMC), the maximum surface excess (Γ_m), micellar aggregation number (N _m) and micellar microenvironment polarity of [C₁₂C _n im]Br decrease, while adsorption efficiency (pC ₂₀), surface pressure at CMC (Π_CMC), the minimum molecular cross-sectional area (A _min) at air-solution interfaces and CMC/C ₂₀ ratio increase.     

Synthesis and Properties of 1,1-bis{[3-(<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-Dimethylamino)propyl]amido}alkane-di-<Emphasis Type="Italic">N</Emphasis>-oxides

A homologous series of new surface-active 1,1-bis{[3-(N,N-dimethylamino)propyl]amido}alkane-di-N-oxides were synthesized in the reaction of an appropriate diethyl 2-alkylmalonate with N,N-dimethylamino-1,3-propanediamine followed by oxidation with aqueous hydrogen peroxide. The adsorption isotherms of their aqueous solutions were measured and evaluated to obtain adsorption parameters: critical micelle concentration (CMC), surface excess concentration (Γ_CMC), equilibrium surface tension at the CMC (γ_CMC), cross-sectional area of the adsorbed surfactant molecule (A _CMC), efficiency of surface adsorption (pC₂₀), standard free energies of adsorption (ΔG°_ads), and micellization (ΔG°_CMC). All investigated di-amidoamines and di-N-oxides were practically non-toxic to selected bacteria and yeasts. These compounds are readily biodegradable in the Closed Bottle Test inoculated with activated sludge. Surface and biological properties showed that this group of N-oxide-type compounds has high surface activity and fulfills requirements for environmental acceptance.

Synthesis and surface properties of chemodegradable anionic surfactants: Sodium salts of sulfated 2-n-alkyl-5-hydroxymethyl-5-methyl-1,3-dioxanes

In acid-catalyzed reactions of long-chain aliphatic aldehydes (Ia-d) (a,R=n-C₅H₁₁; b,R=n-C₇H₁₅; c,R=n-C₉H₁₉; d,R=n-C₁₁H₂₃) with 1,1,1-tris(hydroxymethyl)-ethane (II), 2-n-alkyl-5-hydroxymethyl-5-methyl-1,3-dioxanes (IIIa-d) were obtained. Then they were reacted with SO₃·pyridine complex in dry carbon tetrachloride solution, to obtain trisubstituted derivatives of 1,3-dioxane (IVa-d). They constitute a new group of chemodegradable, acetal-type anionic surfactants, which may readily hydrolyze and oxidize to nonsurfactant compounds. Physical data of the new compounds and some surface properties, such as Krafft point, critical micelle concentration (CMC), surface tension of aqueous solution near CMC (γ_CMC) and wetting and foaming properties, were determined. Sodium salts of sulfated 2-n-alkyl-5-hydroxymethyl-5-methyl-1,3-dioxanes (IVa-d) exhibit aqueous solution properties similar to those of the well-known sodium alkyloligooxyethylene sulfates. Presence of the 5-methyl-1,3-dioxane moiety in molecules of compounds IVa-d introduces hydrophobic character comparable to the effect of three oxyethylene groups (-CH₂CH₂O-) or of two methylene groups (-CH₂-) of the alkyl chain in sodium alkyl ether sulfates [R(OCH₂CH₂)_mOSO₃Na] with equal R value. Part XXV in the series: Chemical Structure and Surface Activity. Part XXIV: A. Sokołowski, B. Burczyk, H.-R. Holzbauer, M. Herbst,Colloids Surfaces 57: 307 (1991).     

Synthesis and surface properties of chemodegradable anionic surfactants: Diastereomeric (2-n-alkyl-1,3-dioxan-5-yl) sulfates with monovalent counter-ions

Sodium, potassium and ammonium cis- and trans-(2-n-alkyl-1,3-dioxan-5-yl) sulfates 6–8 (alkyl: n-C₉H₁₉, 6a–8a, and n-C₁₁H₂₃, 6b–8b) were synthesized in a reaction of aliphatic aldehydes 1a,b with glycerol 2 followed by separation in high yields of individual geometric isomers of cis-and trans-2-n-alkyl-5-hydroxy-1,3-dioxanes, cis-3a,b and trans-3a,b, followed by sulfation with sulfur trioxide-pyridine complex, and finally neutralization with NaOH, KOH, and NH₄OH, respectively. Physical data of the compounds and some surface properties of 2-n-nonyl derivatives, such as critical micelle concentration (CMC), effectiveness of aqueous surface tension reduction (Π_CMC), surface excess concentration Γ_CMC, and the surface area demand per molecule (A_CMC), were determined. It was shown that the surface activity of these compounds is influenced both by their geometric structure and by the monovalent counter-ion.     

Synthesis and surface properties of new dicephalic saccharide-derived surfactants

A new group of nonionic dicephalic saccharide amides, N-dodecyl-N,N-bis[(3-d-gluconylamido)propyl]-amine, N-dodecyl-N,N-bis[(3-d-glucoheptonylamido)propyl]-amine, and N-alkyl-N,N-bis[(3-lactobionylamido)propyl]amines (alkyl: n-C₁₂H_25′ n-C₁₆H_33′, n-C₁₈H₃₇) were synthesized and characterized. Their structure and purity were confirmed by means of ¹H and ¹³C nuclear magnetic resonance analysis and electrospray ionization mass spectrometry. Carbon spectra were verified using a DEPT experiment. The surface and interfacial properties such as critical micelle concentration (CMC), standard free energy of micellization, ΔG _CMC, surface excess concentration, Γ_CMC, and surface area demand per molecule, A _CMC, were determined. The tertiary nitrogen atom seems to have a surprising effect on surfactnat packing at the interface.     

Synthesis, Surface and Thermodynamic Properties of Substituted Polytriethanolamine Nonionic Surfactants

Three series of nonionic surfactants derived from polytriethanolamine containing 8, 10, and 12 units of triethanolamine were synthesized. Structural assignment of the different compounds was made on the basis of FTIR and ¹H‐NMR spectroscopic data. The surface parameters of these surfactants included critical micelle concentration (CMC), surface tension at the CMC (γ_CMC), surfactant concentration required to reduce the surface tension of the solvent by 20 mN m^?1 (pC₂₀), maximum surface excess (Γ_max), and the interfacial area occupied by the surfactant molecules (A_min) using surface tension measurements. The micellization and adsorption free energies were calculated at 25 °C.     

Synthesis and Study of the Surface Properties of Alkylnaphthalene and Alkylphenanthrene Sulfonates

Some alkylnaphthalene and alkylphenanthrene sulfonates were synthesized by means of a Wurtz–Fittig reaction. The HLB values for the prepared compounds were calculated, and the basic properties were studied in water at different temperatures, namely, 25, 35 and 45 °C. Through surface tension measurements, the following values were determined: the critical micelle concentration (CMC) and the surface tension at the CMC (γ_CMC). The following values were calculated: area per molecule at the CMC (A_CMC), standard free energy change of micellization (ΔG _mic), standard free energy of adsorption (ΔG _ad), and the efficiency of a surfactant in reducing surface tension (pC20). Furthermore, the partition coefficients of the synthesized compounds were also measured. The results show that n-alkylnaphthalene and n-alkylphenanthrene surfactants studied exhibit desirable properties that may be of value in some fields such as detergency. To confirm the detergency power of the prepared surfactants, some foam studies were performed.     

Surface active hydroxamic acids. II. Comparison of surface properties of hydroxamic acids with ketones and methyl esters with similar hydrophilic and lipophilic structure

Some surface properties of hydroxamic acids, ketones and methyl esters, which all contained long-chain alkyl[tetra-(oxyethylene)] group, were measured and compared to clarify the influence of the terminal functional group on surface properties. From the results of cloud point (T _cp ), CMC, γ _CMC , adsorption area per molecule at the surface (A) and foaming properties, it was proved that hydroxamic acids had better hydrophilicity and showed better surface properties than the corresponding ketones, methyl esters or typical monodisperse nonionic surfactants.     

Synthesis and Surface Properties of Polyether-Based Silicone Surfactants with Different Siloxane Groups

A series of polyether-based silicone surfactants with different hydrophobic chains (trimethylsiloxy, triethylsiloxy, and triisopropylsiloxy) were synthesized. The molecular structures were confirmed using ¹H nuclear magnetic resonance (NMR), ¹³C NMR, ²⁹Si NMR, and fourier transform infrared spectroscopy (FT-IR). The effect of the siloxane groups on the physicochemical properties, surface tension (γ), critical micelle concentration (CMC), surface tension at the CMC (γ_CMC ), adsorption efficiency (pC₂₀), surface pressure at the CMC (π_CMC ), maximum surface excess (Γ_max ), single silicone surfactant molecule at the air/water interface (A_min ), and the standard free energy of adsorption (), of the polyether-based silicone surfactants was investigated. Results indicate that the polyether-based silicone surfactants can reduce the surface tension of water to approximately 25–31 mN m⁻¹ and the surface activity of silicone surfactants is enhanced with increasing branched trimethylsiloxyl and sterically hindered siloxane groups.     

Synthesis and study of the surface properties of long-chain alkylnaphthalene sulfonates

Long-chain alkylnaphthalene sulfonates were synthesized by means of a Wurtz-Fittig reaction, and the basic properties were studied in water at 30°C. Through surface tension measurements, the following values were determined: the critical micelle concentration (CMC) and the surface tension at the CMC (γ_CMC). The following values were calculated: area per molecule at the CMC (A_CMC), standard free energy change of micellization (ΔG _mic ^o ), standard free energy of adsorption (ΔG _ad ^o ), and the “efficiency” of a surfactant in reducing surface tension (pC₂₀). The micelle aggregation numbers were measured through steady-state fluorescence-quenching methods. As the chain length of the hydrocarbon of n-alkylnaphthalene sulfonate increased, the Krafft temperature increased, the surface tension decreased, the value of CMC decreased, pC₂₀ increased, ΔG _ad ^o and ΔG _mic ^o became more negative, and the micelle aggregation number increased. The results showed that sodium α-(n-decyl)naphthalene sulfonate (DNS) had a high pC₂₀, low Krafft temperature, and lower CMC than other surfactants in this study. Thus, DNS and the other n-alkylnaphthalene surfactants studied exhibit desirable properties that may be of value in some fields such as detergency, oil recovery, and dyes.     

Synthesis and Surface Properties of Disodium Monoalkyl Diphenyl Oxide Disulfonate

Disodium monoalkyl diphenyl oxide disulfonates (MADS) with different carbon chains (C_n‐MADS, n = 8, 12, 16) were synthesized through the steps of alkylation‐sulfonation‐neutralization using fatty alcohols (C₈, C₁₂, C₁₆), diphenyl oxide and fuming sulfuric acid (20 % free SO₃) as reagents. The structures of the products were identified by infrared spectroscopy and electrospray ionization‐mass spectrometry. The surface properties, emulsification, wettability alteration and salinity and hardness tolerance of the products were systematically investigated. The results show that the critical micelle concentration (CMC) of C₈MADS, C₁₂MADS and C₁₆MADS are 7.24 × 10^?3, 1.49 × 10^?3 and 2.09 × 10^?4 mol/L. The surface tensions at the CMC (γ_CMC) of each product are 37.5, 38.9 and 46.8 mN/m. The negative logarithm of the surfactant concentration in the bulk phase required to produce a 20 mN/m reduction in the surface tension of the solvent (pC₂₀) increases with the increase in the alkyl chain length. The emulsifying ability of C₁₂‐MADS is better than C₈‐MADS and C₁₆‐MADS, and the MADS showed less oil‐wet nature. The salinity and hardness tolerance of MADS is much stronger than that of conventional surfactants.