Chemical Structure Of Surfactants Research Articles

Synthesis and Surface Properties Study of a Series of Cationic Surfactants with Different Hydrophobic Chain Lengths

AbstractA series of three cationic surfactants with different chain lengths, i.e. O‐decyl‐, O‐dodecyl‐ and O‐tetradecyl‐N,N′‐diisopropylisourea hydrochloride were synthesized. The chemical structures of the prepared compounds were confirmed using chemical analysis, Fourier transform infra red spectroscopy and nuclear magnetic resonance spectra and chromatography coupled with mass spectrometry. Several surface properties of the synthesized surfactants were studied in aqueous solution. Surface tension, conductivity and the foaming power were measured and the critical micelle concentration (CMC) was determined at 25 °C. These results were correlated to the surfactant chemical structure. The surfactant that provided the best surface activity was the O‐dodecyl‐N,N′‐diisopropylisourea hydrochloride. The CMC was found to be significantly dependent on the hydrophobic chain length and decreased with increasing of the carbon number in the alkyl chain. The surfactants synthesized have an interesting foaming power. The surfactant with the longest alkyl chain exhibited the highest foamability.

The study of Sunset Yellow anionic dye interaction with gemini and conventional cationic surfactants in aqueous solution

In the present study, the interaction of an anionic azo dye , Sunset Yellow, with two cationic gemini surfactants with different spacer lengths ( s = 3, 6 methylene groups) and their monomeric counterpart, dodecyl trimethyl ammonium bromide (DTAB), was investigated by surface tension, UV–Vis spectroscopy, and zeta potential measurements . The critical micelle concentration (CMC) was determined from plots of the surface tension ( γ ) as a function of the logarithm of total surfactant concentration. Moreover, the values of binding constants ( K b ) of dye-surfactant complexes were calculated by UV–Vis spectroscopy. The UV–Vis spectra showed that the dye–surfactant interaction occurred in the solution at concentrations far below the CMC of each surfactant. The gemini surfactant with a shorter spacer showed stronger interaction with dye in comparison to DTAB and the gemini with longer spacer. The effect of surfactant chemical structure on solubilization of dye-surfactant aggregates at surfactant concentration above CMC was investigated by zeta potential . ► The interaction between Sunset Yellow dye and the studied surfactants is electrostatic interaction. ► The zeta potential data show that the solubilization capacity for the Gemini surfactants aggregates is larger. ► The maximum colloid stability is attributed to be at SSY/12-3-12 system.

QSPR for HLB Values of Nonionic Surfactants Using Two Simple Descriptors

By using the quantitative structure-property relationship (QSPR) method, the relationship between the hydrophilic-lipophilic balance (HLB) value and the chemical structure of surfactants were studied for nonionic surfactants of the ethoxylated alcohols and ethoxylated alkylphenols, for which the number of EO groups is less than 20. The obtained best QSPR model contains only two simple descriptors. One is zero order of Kier-Hall index (KH0); the other is the number of oxygen atoms in the hydrophilic group (N o). The correlation coefficient (R 2) is as high as 0.984. The resulted QSPR model shows a significantly higher accuracy with respect to the effective chain length method.

Synthesis of Some Novel Nonionic Ethoxylated Surfactants Based on α-Amino Acids and Investigation of Their Surface Active Properties

Eight novel ethoxylated nonionic surfactants were prepared based on oil soluble α-amino acids. The L-phenylalanine and L-leucine were esterified and amidated with cetyl alcohol and palamitic acid, respectively; two amides and two esters of α-amino acids were obtained. The ethylene oxide was condensed with the prepared amides and esters to get three different polyethylene oxide units (40, 60, and 100) as phenylalanine derivatives. The amide and ester of α-L-leucine were ethoxylated at (60 ethylene oxides units). The analytical micro analysise, FTIR, 1H NMR, 13C NMR, mass spectra were carried out to confirm the chemical structures. The surface tension of the water soluble prepared compounds was measured at 25°C, further the surface active properties were determined and calculated. Such that critical micelle concentration (CMC), surface excess (Γmax); area per molecule (Amin), effectiveness (γCMC) free energy of micellization and adsorption (ΔGmic, ΔGad). From the data obtained it was found that the CMC of phenylalanine esters is greater than that obtained for the amide derivatives. The Γmax decreased as the ethylene oxide units (EO) increased. It was found also that the ΔGad was greater than the ΔGmic. The obtained data and discrepancy were discussed on the light of surfactant chemical structure.

Effect of surfactant structure on the residual fluorescence of micelle-based fluorescent probes

In the present paper we have investigated some photo-physical characteristics of different micellar-based fluorescent probes containing a fluorophore (pyrene) and a quencher unit (dodecyl-dioxo 2,3,2). The fluorescent response of the probe in the presence of Cu(II) ions was studied using different micellar substrates, and it was found that the pH at which the On–Off jump occurs is not influenced by the chemical structure of surfactant. In addition, the experimental residual fluorescence is not proportionally affected by microviscosity or by the size of the micellar aggregates. The signal of the native fluorescence of pyrene was observed even when the quencher's occupancy number was greater than one. Moreover, we observed discrepancies between experimental values and calculated residual fluorescence using Laplace data. These results were interpreted suggesting that the residual fluorescence has two main components, one that seems to be independent on micellar properties, while the other is directly related to location of molecules inside the surfactant aggregates that serve as substrate.

The effect of ionic strength and hardness of water on the non-ionic surfactant-enhanced remediation of perchloroethylene contamination

The objective of this study is to evaluate the perchloroethylene (PCE) removal by an aqueous surfactant solutions based on influential factors (ionic strength, hardness) of various groundwaters and surface waters contaminated with PCE. The experimental methods used in this study were separatory funnel experiments and batch experiments. Separatory funnel experiments were performed to determine which surfactants are good solubilizers for PCE. Batch experiments were performed to evaluate the effect of ions in sampled water for PCE removal. The results of separatory funnel experiments indicated that the surfactant polyoxyethylene (20) sorbitan monostearate (Tween 60) showed to be a predominant solubilizer for the removal of PCE (87.3%). Separatory funnel experiments also showed that the hydrophilic–lipophilic balance (HLB) number and the chemical structure of the surfactants were good indicators of surfactant effectiveness for removal of PCE from water. The results of batch experiments showed that non-ionic surfactants are affected by the ionic strength of sampled water. The % of PCE removal of the Tween 60 surfactant solution was measured to be 88.3% by batch experiments. This result was affected by the characteristics of the surfactant (HLB, chemical structures) and the ionic strength of water. Therefore, the ionic strength of contaminated water, HLB and chemical structures of surfactants must be considered in surfactant-enhanced remediation.

Surfactants and interfacial phenomena

Surfactants and interfacial phenomena

Polycarbonate nanocomposites. Part 1. Effect of organoclay structure on morphology and properties

Polycarbonate nanocomposites were prepared by melt processing from a series of organoclays based on sodium montmorillonite exchanged with various amine surfactants. To explore the effects of matrix molecular weight on dispersion, an organoclay was melt-mixed with a medium molecular weight polycarbonate (MMW-PC) and a high molecular weight polycarbonate (HMW-PC) using a twin screw extruder. The effects of surfactant chemical structure on the morphology and physical properties were explored for nanocomposites formed from HMW-PC. Wide angle X-ray scattering, transmission electron microscopy, and stress–strain behavior were employed to investigate the nanocomposite morphology and physical properties. The modulus enhancement is greater for nanocomposites formed from HMW-PC than MMW-PC. This trend is attributed to the higher shear stress generated during melt processing. A surfactant having both polyoxyethylene and octadecyl tails shows the most significant improvement in modulus with some of the clay platelets fully exfoliated. However, the nanocomposites formed from a range of other organoclays contained both intercalated tactoids and collapsed clay particles with few, if any, exfoliated platelets.

Biodegradation of fatty alcohol ethoxylates in the continuous flow activated sludge test

Biodegradation of two fatty alcohol ethoxylates: surfactant C12E10 (C 12 with an average 10 oxyethylene subunits (EO)) and Marlipal 1618/25 (C 16–18 with an average 25 EO) were tested under the continuous flow activated sludge conditions of the classical Husmann plant and a plant having a denitrifying chamber. Primary biodegradation and concentration of metabolites: free fatty alcohol (FFA) and poly(ethylene glycols) (PEG) were measured. PEG were divided into two fractions: short-chained (1–3 EO) and long-chained PEG (>3 EO). Tensammetric methods were used for analysis. High primary biodegradation was found (96.8±0.5% for surfactant C12E10 (C12E10) and 99.6±0.1% for Marlipal 1618/25 (Marlipal)), though with a high concentration of metabolites: FFA and PEG. FFA concentration corresponded to 30–100% of theoretically predicted concentration (presuming central fission) and dependent on the chemical structure of surfactant and type of plant used for testing. Total PEG concentration was about 20% of that predicted on the basis of central fission, while the ratio of short-chained PEG in the total PEG varied from 20 to 70% and depended on the chemical structure of surfactant and type of plant used for testing.

Aggregation Properties of Sodium Hyaluronate with Alkanediyl-α,ω-bis(dimethylalkylammonium Bromide) Surfactants in Aqueous Sodium Chloride Solution

Aggregation properties of sodium hyaluronate (NaHA) with alkanediyl-α,ω-bis(dimethylalkylammonium bromide) surfactants (referred to as dimeric surfactants) in aqueous sodium chloride solutions have been studied as a function of surfactant chemical structure. Surface tension measurements indicate the unusual parabolic dependence of surface tension vs log surfactant concentration with a surface tension minimum at concentration cmin. The increase of surface tension above cmin may be related to the formation of clusters consisting of NaHA chain and dimeric surfactants at the air–water interface and in the bulk. From light scattering measurements, molecular weight, hydrodynamic radius, and second virial coefficient have been calculated. The simple calculation of the ratio of positive charge of dimeric surfactant unit per one negatively charged hyaluronate disaccharidic unit in NaHA–surfactant complex reveals that there is a slight excess of positive surfactant charges per one negatively charged disaccharidic unit in the region around cmin and the NaHA–surfactant complex is not far from electroneutrality. The nonlinear behavior of viscosity vs surfactant concentration in the NaHA–dimeric surfactant system depends on surfactant chemical structure. The behavior is concerned with the size increase due to complex growth and with the size shrinkage above cmin. A model describing the behavior of NaHA–surfactant complex in the bulk and at the interface is suggested.

Wet cleaning of historical textiles: surfactants and other wash bath additives

The paper is a review of the literature relating to the use of water, surfactants and other additives for cleaning historical textiles. Ethical considerations are introduced and the common types of soil that occurs on historical textiles are characterized. The review covers publications on the advantages and disadvantages of wet cleaning and discusses the properties of water, detergents and surface active agents. The paper underlines the importance of the HLB value, critical micelle concentration, solubility of surfactants, Krafft and cloud point in conservation. Washing processes using surface active agents, the connection between the chemical structure of surfactants and detergency, the role of soil/dirt antiredeposition agents, foam, pH, washing time and temperature in cleaning are discussed and the composition of solutions for washing historical textiles are given. The paper introduces the dependence of rinsing on the adsorption of surfactant to textiles and reviews the use of vacuum suction in wet cleaning. The efficiency of washing and the effect of washing on fibres, textiles and dyes is assessed and the review ends with references to biodegradation of surfactants and a list of selected case studies.

Enzyme activity and stability control by amphiphilic self-organizing systems in aqueous solutions

The interaction of surfactants with proteins in aqueous solutions has been the subject of many investigations to understand the interactions between membrane proteins and lipids, structurally similar to synthetic surfactants. The effect of surfactant on enzyme structure and activity is the result of chemically selective interactions that may be influenced both by the enzyme structure and by the chemistry of the surfactant. For many years, surfactants have been considered as non-specific denaturants of proteins, even if in the literature several of them are reported to enhance activity and/or stability of some enzymes: the detergent can interact with the enzyme and cause a conformational change to a more active form and/or stabilize its native folded structure. Although the surfactant head group seems to have a determining role, other structural features of the detergent are also important in influencing the catalytic properties of an enzyme, i.e. head group size and its hydrophobic/hydrophilic balance. Up to now it is very difficult to predict the molecular features of the surfactant and an extensive investigation on the relationship between the surfactant chemical structure and the catalytic properties of enzyme is still required.

Wet cleaning of historical textiles: surfactants and other wash bath additives

The paper is a review of the literature relating to the use of water, surfactants and other additives for cleaning historical textiles. Ethical considerations are introduced and the common types of soil that occurs on historical textiles are characterized. The review covers publications on the advantages and disadvantages of wet cleaning and discusses the properties of water, detergents and surface active agents. The paper underlines the importance of the HLB value, critical micelle concentration, solubility of surfactants, Krafft and cloud point in conservation. Washing processes using surface active agents, the connection between the chemical structure of surfactants and detergency, the role of soil/dirt anti-redeposition agents, foam, pH, washing time and temperature in cleaning are discussed and the composition of solutions for washing historical textiles are given. The paper introduces the dependence of rinsing on the adsorption of surfactant to textiles and reviews the use of vacuum suction in wet cleaning. The efficiency of washing and the effect of washing on fibres, textiles and dyes is assessed and the review ends with references to biodegradation of surfactants and a list of selected case studies.

Cationic and Zwitterionic Polymerizable Surfactants: Quaternary Ammonium Dialkyl Maleates. 1. Synthesis and Characterization

Cationic and zwitterionic reactive dialkyl maleates with different hydrophobic chain lengths (R = C10H21, C12H25, C16H33, and C18H37), and some similar surfactants without double bonds were synthesized with an aim to use them as stabilizers in the batch and seeded emulsion copolymerization of styrene and butyl acrylate (part 2 of this series). Surfactants are obtained in a three-step synthesis, starting from ring opening of maleic anhydride, followed by O alkylation with an aminoalkyl compound, and finishing with quaternization of the amino group in the hydrophilic part of the molecule. The chemical structure of surfactants was confirmed by 1H NMR. Melting points and critical micelle concentrations of the synthesized surfactants were measured. The specific area per molecule at the air/water interface was calculated for most of the surfactants. The adsorption of the surfactant on the polystyrene (PS) and PS/poly(butyl acrylate) copolymer was also measured, and the specific area occupied by the surfactant molecule was calculated in one example.

Mechanism of the immobilization of surfactants on polymeric surfaces by means of an argon plasma treatment: Influence of the chemical structure of surfactant and substrate

Mechanism of the immobilization of surfactants on polymeric surfaces by means of an argon plasma treatment: Influence of the chemical structure of surfactant and substrate

Zwitterionic polymers with carbobetaine moieties

A series of new monomeric and polymeric carbobetaines based on acrylamides has been synthesized and characterized. Due to long hydrocarbon substituents, the compounds have chemical structures of surfactants and polysoaps, respectively. Results are compared with those of analogous poly(sulfobetaine)s. The poly(carbobetaine)s are more hygroscopic and show improved solubility. Viscometric studies in ethanol show no, or only weak, polyelectrolyte behaviour. Thermal stability is decreased, and glass transitions occur at lower temperatures. X-ray diffractograms indicate the presence of superstructures whose detailed forms depend on the polymers' geometry. Copyright (C) 1996 Elsevier Science Ltd.

Critical Micellization Concentration of Surfactants in Aqueous Solution and Free Energy of Micellization

The relationship between the critical micellization concentration (cmc) of a surfactant in solution and its free energy of micellization is probably the most widely used one in surfactant science. Until recently, most surfactants discussed in the literature were made up of one polar head group, nonionic or ionic, bonded to a single hydrophobic moiety. Recently, studies have been initiated on new types of ionic surfactants: bolaforms, surfactants with divalent counterions, gemini, or dimeric surfactants, etc. This paper first derives the relationship between the cmc and for a very general type of ionic surfactant, made up of a surfactant ion containing i polar groups of valency zs bonded to j alkyl chains, with counterions of valency zc. The form of this relationship is examined for several types of ionic surfactants. It is shown that many reported studies did not use the correct relationship to evaluate the free energy of micellization from the value of the cmc. In particular, the counterion contribution was often neglected, which resulted in large errors. The use of the correct equations is shown to yield values for the free energy of transfer of a methylene group from water to the micellar pseudophase which are largely independent of the surfactant chemical structure, as it is to be expected.

USING SURFACTANTS TO ENHANCE DRAINAGE FROM A DEWATERED COLUMN

Our objective was to determine the efficacy of surfactants as secondary recovery agents to enhance drainage from a previously dewatered sand column. Seventeen surfactants at concentrations of 0, 0.01, 0.1, 1.0, 10.0, and 100 g (solid) or ml (liquid) surfactant per liter of water were evaluated. Anionic, cationic, and nonionic classes of surfactants were represented. Surfactant solutions (150 ml) were added to the top of dewatered sand columns (0.1-m diameter by 0.5-m length), and column outflow was measured. Each treatment was replicated four times. Between surfactants additions, columns were cleaned with 500 ml of methanol and 750 ml of tap water. Outflow significantly increased as the log of surfactant concentration increased, but no surfactant class was significantly more efficient than any other class. Surface tension was significantly correlated with log of concentration (-0.73) and outflow (-0.42). This indicated that decreases in surface tension are associated with increases in column dewatering. Outflows from the less than 1 g or ml surfactant per liter of water treatment were not significantly different from the blank (no surfactant). Surfactant chemistry was additionally evaluated using several Igepal DM surfactants with differing numbers of ethyleneoxy (EO) units. Maximum outflow occurred at EO ratios of 15.3, indicating that surfactant chemical structure is also important. The high concentration of surfactant required to show significant benefits (1 g or ml per L) probably precludes use of surfactants as secondary recovery agents for water.

Microemulsion structure in four-component systems for different surfactants

The microstructure of four-component microemulsions composed of ionic surfactant, cosurfactant hydrocarbon and water was studied as a function of surfactant polar head group and alkyl chain length using the multi-component self-diffusion approach, the self-diffusion coefficients being measured by the Fourier transform pulsed-gradient spin-echo 1H-NMR technique. The study concerned both cationic and anionic surfactants and was performed for two cosurfactants, i.e. pentanol and octanol, and a number of hydrocarbons (aliphatic and aromatic). The results obtained demonstrate that in every case the structure is very strongly influenced by the chain length of the alcohol, a longer cosurfactant favouring a droplet-type structure and a shorter one a bicontinuous structure; this occurs irrespectively of the chemical structure of the surfactant and the nature of the oil used. The main effect of the hydrocarbon and surfactant chain lenghts is to influence the distribution of molecules between different domains. The hydrocarbon chain length determines the distribution of oil and alcohol between the medium and the surfactant layers through a competition process that is not affected by the surfactant chemical structure. Furthermore, in a water-in-oil droplet situation, in addition to the larger degree of penetration for shorter alkanes between the surfactant molecules in comparison with the corresponding bicontinuous situation, we have an increased interfacial location of the alcohol with an increase of the surfactant tail length.

Adsorption of Nonionic Oxyethylated Sulfonamides onto Sand and Kaolin from Aqueous Solution

AbstractNonionic surfactants continue to be used as soil conditioners, principally as wetting agents, but optimum surfactant chemical structure has not as yet been completely established. This research using nonionic surfactants, alkyl substituted polyoxyethylated phenylsulfonamides, has determined the effect of varying the ethoxy content and the alkyl side chain on three surfactant characteristics, i.e., adsorption, wetting, and dispersion. It was found that surfactant adsorption on sand and kaolin, two soil components, at a constant pH of 6.0 decreased with higher surfactant ethoxy content. Changing the alkyl side chain from C6 to C8 to C10 increased the apparent surfactant attraction for the adsorbent surface but not the total amount of surfactant adsorbed. The amount of surfactant adsorbed determines the final nature of the adsorbent's surface and its hydrophobic or hydrophilic character. Thus, the wetting and dispersing properties of soil components can be set by the amount of surfactant adsorbed.