Environmental Impact of Ether Carboxylic Derivative Surfactants

The ultimate aerobic biodegradability and toxicity of three ether carboxylic derivative surfactants having different alkyl chains and degrees of ethoxylation were investigated. Ultimate aerobic biodegradability was screened by means of dissolved organic carbon determinations at different initial surfactant concentrations. For comparison, the characteristic parameters of the biodegradation process, such as half-life, mean biodegradation rate, and residual surfactant concentration, were determined. Increased surfactant concentrations decreased mineralization and lengthened the estimated half-life. The results demonstrate that the ultimate aerobic biodegradability is higher for the surfactants with the shortest alkyl chain and highest degree of ethoxylation. Toxicity values of the surfactants, and their binary mixtures, were determined using three test organisms, the freshwater crustacea Daphnia magna, the luminescent bacterium Vibrio fischeri and the microalgae Selenastrum capricornutum. The toxicity is lower for the surfactants with the shortest alkyl chain and highest degree of ethoxylation. The toxicity of binary mixtures of the three ether carboxylate surfactants at a 1:1 weight ratio was also measured. The least toxic mixture is formed by the surfactants having lower individual toxicity.     

Ozonation of Anionic and Non-ionic Surfactants in Aqueous Solutions: Impact on Aquatic Toxicity

The objective of this study was to investigate the influence of ozonation of anionic and non-ionic surfactants on their aquatic toxicity. Toxicity values of various commercially important anionic and non-ionic surfactants have been determined using the luminescent bacterium Vibrio fischeri. Surface tension measurements were made to study the interfacial activity. The behavior depends on the chemical structure. Some intermediate ozonation products were found to be more toxic than the base surfactant and others were found to be less. Surfactants with aromatic rings such as linear alkyl benzene sulfonates, or surfactants with glycosidic groups such as alkylpolyglucosides, exhibit a lower toxicity after ozonation. On the other hand, ether groups present in the fatty-alcohol ethoxylates and ether carboxylic derivative surfactants, and carboxylic acid derivates present in the ether carboxylic derivative surfactants lead to increasing toxicity after ozonation. Surfactants with ether groups probably formed short-chain polyethoxylated compounds and carboxylic acids, which are possibly responsible for the surface-tension decrease that promotes the toxicity increase.     

Properties of Sodium Methyl Ester Alpha-Sulfo Alkylate/Trimethylammonium Bromide Mixtures

The surface properties of binary mixtures of anionic sodium methyl ester ??-sulfo alkylate (C _m MES) and cationic alkyl trimethylammonium bromide (C _n TAB) of different carbon chain length have been studied in the present work. The critical micelle concentration (CMC) that was obtained from the plots of surface tension (??) versus concentration showed that mixed surfactants have CMC values that were about 10 times lower than their single components. The large negative values for both interaction parameters suggest the existence of strong synergism between the oppositely charged surfactant molecules. The effect of hydrocarbon chain length of either surfactant was also compared and results showed that the effect of cationic surfactant chain length dominated that of the anionic surfactants. It was also discovered that certain mixed surfactant combinations behave differently from the expected trend.     

Synergism and Performance for Systems Containing Binary Mixtures of Anionic/Cationic Surfactants for Enhanced Oil Recovery

The surfactant structure–performance relationship and application properties in enhanced oil recovery (EOR) for binary mixtures of anionic and cationic surfactants are presented and discussed. A polyoxyethylene ether carboxylate anionic surfactant was blended with a quaternary ammonium chloride cationic surfactant and tested for a high-temperature, low-salinity, and high-hardness condition as found in an oil reservoir. These mixtures were tailored by phase behavior tests to form optimal microemulsions with normal octane (n-C8) and crude oil having an API gravity of 48.05°. The ethoxy number of the polyoxyethylene carboxylate anionic surfactant and the chain length of the cationic surfactant were tuned to find an optimal surfactant blend. Interfacial tensions with n-C8 and with crude oil were measured. Synergism between anionic and cationic surfactants was indicated by surface tension measurement, CMC determination, calculation of surface excess concentrations and area per molecule of individual surfactants and their mixtures. Molecular interactions of anionic and cationic surfactants in mixed monolayers and aggregates were calculated by using regular solution theory to find molecular interaction parameters β ^σ and β ^M . Morphologies of surfactant solutions were studied by cryogenic TEM. The use of binary mixtures of anionic/cationic surfactants significantly broadens the scope of application for conventional chemical EOR methods.     

Alkyl Xylosides: Physico‐Chemical Properties and Influence on Environmental Bacteria Cells

A group of four selected non‐ionic surfactants based on carbohydrates, namely octyl d ‐xyloside (C₈X), nonyl d ‐xyloside (C₉X), decyl d ‐xyloside (C₁₀X) and dodecyl d ‐xyloside (C₁₂X), have been investigated to accomplish a better understanding of their physico‐chemical properties as well as biological activities. The surface‐active properties, such as critical micelle concentration (CMC), emulsion and foam stability, the impact of the compounds on cell surface hydrophobicity and cell membrane permeability together with their toxicity on the selected bacterial strains have been determined as well. The studied group of surfactants showed high surface‐active properties allowing a decrease in the surface tension to values below 25 mN m^?1 for dodecyl d ‐xyloside at the CMC. The investigated compounds did not have any toxic influence on two Pseudomonas bacterial strains at concentrations below 25 mg L^?1. The studied long‐chain alkyl xylosides influenced both the cell inner membrane permeability and the cell surface hydrophobicity. Furthermore, the alkyl chain length, as well as the surfactant concentration, had a significant impact on the modifications of the cell surface properties. The tested non‐ionic surfactants exhibited strong surface‐active properties accompanied by the significant influence on growth and properties of Pseudomonas bacteria cells.     

Effects of Molecular Structure and Temperature on Micellization of Cationic Ammonium Gemini Surfactants in Aqueous Solution

Micellization of four cationic quaternary ammonium gemini surfactants, having a diethyl ether or hexyl spacer with the alkyl chain lengths of 12 and 16 carbon atoms, was studied using isothermal titration microcalorimetry (ITC) and electrical conductivity measurements in the temperature range from 298.15 to 313.15 K. In this temperature range, where surfactants are normally applied, the temperature almost does not influence the critical micelle concentration (CMC) and the degree of micelle ionization (α) values of the gemini surfactants, and the replacement of a hexyl spacer by a diethyl ether spacer leads to a slight decrease in the CMC and α values. However, as the alkyl chain length increases from 12 to 16 carbon atoms, the CMC values significantly decrease from 0.99–1.19 mM to 0.020–0.057 mM. In particular, the enthalpy of micellization (ΔH_mic ) and the associated thermodynamic parameters show obvious changes with varying temperature and molecular structure. ΔH_mic becomes much more exothermic at higher temperature or for the surfactants with a more hydrophilic spacer. Moreover, the heat capacity change of micellization (ΔC _{P, mic} ) is less exothermic for the surfactants with a more hydrophilic spacer or a longer alkyl chain. The enthalpy–entropy compensation data show that the surfactants with longer alkyl chains have a more stable micellar structure.     

Synthesis and Surface Tension Study of the Spacer Chain Length Effect on the Adsorption and Micellization Properties of a New Kind of Carboxylate Gemini Surfactant

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(γ_CMC), the tendency of micellization versus adsorption, CMC/C₂₀, the minimum area per surfactant molecule at the air/solution interface (A_CMC), all decrease with increasing spacer chain length; surface reduction efficiency, pC₂₀, the surface excess at the air/solution interface (Г_CMC) 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.     

Surface Parameters and Biological Activity of <Emphasis Type="Italic">N</Emphasis>-(3-(Dimethyl Benzyl Ammonio) Propyl) Alkanamide Chloride Cationic Surfactants

Three cationic surfactants containing amide groups were prepared by quaternization of dimethylaminopropylamine with benzyl chloride. FTIR and ¹H-NMR spectroscopy were used to confirm the chemical structure of the prepared cationic surfactants. The surface parameters were estimated using surface tension measurements at three different temperatures. The prepared cationic surfactant showed a lower CMC than conventional cationic surfactants. Thermodynamic parameters of adsorption and micellization depend mainly of alkyl chain length and temperature. The adsorption process is more favorable than micellization. The biological activity of the three surfactants was estimated using inhibition zone showing that amidoamine cationic surfactants have good activity and the surfactants C12Bn is the most effective one.     

Solution Properties of Alkyl β-D-Maltosides

Alkyl β-D-maltosides are an important class of sugar-based nonionic surfactants and have been widely studied. Nevertheless, it is still necessary to investigate further their amphiphilic structure-surface property relationships. In this article, we reported a series of properties of synthetic alkyl β-D-maltosides ( 6a – 6i , n = 6–18) including their hydrophilic–lipophilic balance (HLB) number, water solubility, hygroscopicity, moisture-retention capacity, foaming ability, surface tension, thermotropic phase behavior, and skin irritation. Their HLB number and water solubility decreased with increasing alkyl chain length. Hexyl β-D-maltoside exhibited the strongest hygroscopicity and moisture-retention capacity. Decyl β-D-maltoside and dodecyl β-D-maltoside possessed excellent foaming power and foaming stability. Furthermore, the critical micelle concentration (CMC) of alkyl β-D-maltoside ( 6a – 6g , n = 6–14) and their surface tension at CMC decreased with increasing alkyl chain length. At last, alkyl β-D-maltosides ( 6a – 6g ) should be considered as safe surfactants by the skin irritation assessment.     

Mixtures of Nonionic Surfactants made from Renewable Resources with Alkyl Sulfates and Sodium n-Alkanecarboxylates: Comparison of Mixing Behavior using Rubingh’s Treatment

Binary aqueous mixtures of (1) alkyl glucopyranosides (glycosides), (2) alkyl maltopyranosides (maltosides), or (3) alkyl N-methyl glucamines with (1′) sodium alkyl sulfates or (2′) sodium n-alkyl carboxylates were investigated in an effort to evaluate physiochemical properties for mixtures of surfactants from renewable resources. Solutions at various concentrations and mixture ratios were tested and evaluated to determine critical micelle concentrations (CMCs). The greatest reduction in CMC was found for surfactants with long and intermediate hydrophobe lengths. In agreement with other studies, an increase in hydrophilic group size and flexibility decreased the electrostatic repulsion of ionic-nonionic mixed micelles as evidenced by a more negative Rubingh’s β parameter. However, at low hydrophobe length, carboxylate and glycoside headgroup mixtures produced mixed micelle interactions displaying synergism at low nonionic surfactant mole fractions and slight antagonism at high nonionic mole fractions. The asymmetry in interaction produces an S-shaped CMC curve and demonstrates that the one-parameter Rubingh model is insufficient in describing both synergism and antagonism for this binary mixture.     

Preparation and properties of double- or triple- chain surfactants with two sulfonate groups derived fromN- Acyldiethanolamines

Bis(sulfonate) types of amphipathic compounds with three long- chain alkyl groups were prepared by the reaction ofN- (long- chain acyl)diethanolamine diglycidyl ethers with long- chain fatty alcohols, followed by the reaction with propanesultone. The diglycidyl ethers were easily obtained from the correspondingN- acyldiethanolamines and epichlorohydrin in the presence of a phasetransfer catalyst. The same types of compounds with two longchain alkyl groups were also prepared from Nacetyldiethanolamine according to similar procedures. All these new double- or triple- chain surfactants were soluble in water and showed much better micelle forming and ability to lower surface tension than general types of single- chain surfactants with one sulfonate group. The critical micelle concentration (CMC) and γ_CMC values of the triple- chain compounds were still much smaller than those of the corresponding double- chain compounds with two common alkyl groups. The efficiency of adsorption at the water/air interface (pC₂₀) of these surfactants was very high. Their foaming properties, wetting ability toward a felt chip, and lime- soap dispersing ability were measured. To whom correspondence should be addressed at Department of Applied Chemistry, Faculty of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565, Japan.     

Synthesis,surface, thermodynamic properties and Biological activity of dimethylaminopropylamine surfactants

The chemical structure of the prepared cationic surfactants which formed through condensation reaction between dimethylaminopropylamine (DMAPA) and butyraldehyde then quaternized by three fatty alkyl bromide was confirmed by FTIR, ¹HNMR and mass spectroscopy. The chemical structure of prepared compounds has an effect on surface properties. By increasing the hydrophobic chain length, the values of CMC and Г_max decrease while A_min value was increased. The Thermodynamic parameters showed that adsorption and micellization processes are spontaneous. It is clear that the prepared cationic surfactants tend to adsorb at surface, then it aggregate to form micelle. The prepared surfactants showed good biological activity against Gram-positive and negative bacteria and fungi. The prepared cationic surfactant showed aggressive effect on the sulfate reducing bacteria growth.     

Synthesis and Surface Activities of Novel Succinic Acid Double-Tailed Sulfonate Fluorinated Surfactants

In this study, four environmentally friendly succinic acid double-tailed sulfonate fluorinated surfactants were synthesized from maleic anhydride, fluoroalkyl alcohols, namely 1-(1H,1H,7H-Dodecafluoroheptyloxy) ethanol, 1-(1H,1H,5H -octafluoropentyloxy) ethanol, 1-(1H,1H,3H-tetrafluoropropoxy) ethanol, and 1-(1H,1H -trifluoroethyoxy) ethanol, and sodium hydrogensulfite. The surfactant structure was characterized by FT-IR, ¹H NMR, and ¹⁹F NMR . Thermogravimetric results showed that the fluorinated surfactants were stable up to relatively high temperature. The Krafft points of the four novel succinic acid double-tailed sulfonate fluorinated surfactants were all below 0 °C. The lowest CMC value for the synthesized four double-tailed fluorine surfactants is about 0.076 mmol L^?1, far less than that of ammonium perfluorooctanoate (PFOA), demonstrating that double-tailed surfactants have higher surface activity than surfactants with one fluoroalkyl chain. The replacement of alkyl groups with oxyethylene groups enhances the hydrophilicity of the obtained fluorinated surfactants. Based on these findings, the synthesized surfactants may be environmentally friendly alternatives to PFOA and exhibit promising potential in industry applications.     

On the Applicability of the Regular Solution Theory to Multicomponent Systems

The critical micelle concentration (CMC) of aqueous mixtures of decyl- (C₁₀TAB), dodecyl- (C₁₂TAB), and tetradecyl trimethyl ammonium (C₁₄TAB) bromides has been studied in the complete triangular diagram. The results have been analyzed on the basis of the multicomponent regular solution theory for mixed micelles (MRST). It has been found that the mixtures of both, two or three components, contrary to the MRST theory assumptions, have a nonideal behavior. Both the experimental CMC, (CMC _ijk )_exp, and that computed with the MRST, (CMC _ijk )_calc), were lower than the ideal one, (CMC _ijk )_id, indicating an attractive interaction. Moreover, in the majority of the triangular diagram (CMC _ijk )_exp differs significantly from (CMC _ijk )_calc. This suggests that the assumption in the MRST that the interaction among the three different homologue molecules in the mixed micelle computed using the binary regular solution theory interaction parameters obtained from binary mixtures may be an oversimplification. This has been reinforced by analysis of the intramicellar activity coefficients of components, indicating differences in the surrounding of the component molecules when they are in bi- or tricomponent micelles. The excess free energy of micellization in three-component systems indicates that the more stable mixed micelles are those having an excess of the shorter components (C₁₀TAB–C₁₂TAB) and <50 % of the longer one (C₁₄TAB). Furthermore, the common statement that mixtures of homologue surfactants are ideal is not supported by this work.     

Aggregation and Thermodynamic Properties of Some Cationic Gemini Surfactants

In this study, the gemini surfactants of the alkanediyl-α-ω-bis(alkyl dimethyl ammonium) dibromide type, on the one hand, with different alkyl groups containing m carbon atoms and an ethanediyl spacer, referred to as “m-2-m” (m = 10, 12 and 16) and, on the other hand, with n-C₁₆ alkyl groups and different spacers containing s carbon atoms, referred to as “16-s-16” (s = 2, 6, 10 and Ar (8)) have been synthesized, purified and characterized. The critical micelle concentration (CMC), micelle ionization degree (α) and Gibbs free energy of micellization (∆G _mic) of these surfactants and the monomeric cationic surfactants DTAB and CTAB have been determined by means of electric conductivity measurements. In addition, the temperature dependence of the CMC was determined for the 10-2-10 gemini surfactant. The CMCs of the gemini surfactants are found to be much lower than those of the corresponding monomeric surfactants and the effect of the hydrophobic alkyl chain length is more important than that of the spacer. The CMC of 16-s-16 passes through a maximum of (or around) s = 6 and then decreases for s = 10. The presence of a maximum CMC is explained by the contribution of a change of conformation of the surfactant with increasing spacer chain length. The changes of α with s and m are found qualitatively similar to those found for CMC values. The values of ∆G _mic are more negative for the dimers than for the monomers and also change with an increasing spacer carbon number, as CMC values do. The thermodynamic parameters of micellization indicate that the micellization of 10-2-10 is enthalpy driven.     

Purification,Surface Tensions,and Miscibility Gaps of Alkyldimethyl and Alkyldiethylphosphine Oxides

Alkyldimethyl (C _n DMPO) with chain lengths of n = 8 (octyl), 10 (decyl), 12 (dodecyl), and 14 (tetradecyl) as well as alkyldiethyl (C _n DEPO) phosphine oxides with chain lengths of n = 10, 12, and 14 were synthesized and purified to study how the adsorption properties and the location of the miscibility gap of these surfactants depend on the size of the head group and on the length of the alkyl chain. After surfactant purification, the surface tension isotherms were determined from which the cmc, the minimum surface tension σ_cmc, the maximum surface concentration Γ_max, and the minimum surface area A _min were obtained. As expected, for one homologous series, a decrease in the cmc and an increase in Γ_max was observed with increasing alkyl chain length. For two surfactants of the same alkyl chain length, the cmc values of the C _n DEPO surfactants are approximately two times lower than those of the C _n DMPO surfactants. However, the Γ_max values of C _n DEPO are lower than those of C _n DMPO as two ethyl chains are sterically more demanding than two methyl chains. In addition to the adsorption properties, the location of the miscibility gap as a function of the alkyl chain length and the head group size was studied. Its location depends on the total number of carbon atoms and not primarily on the length of the main alkyl chain. This observation reflects the decreasing water solubility which can be tuned by increasing the length of either the main alkyl chain or of the shorter head group chains.     

Synthesis and Surface Activities of Amidobetaine Surfactants with Ultra-long Unsaturated Hydrophobic Chains

Recent studies have shown that the surfactants bearing an ultra-long hydrophobic chain (>C18) exhibit unique self-assembly properties. However, their synthesis and surface activities have been less documented. In this work, monounsaturated alkyl dimethyl amidopropyl betaines, UCnDAB (n?=?18, 22, and 24), were prepared by the reaction of the corresponding fatty acids with N,N-dimethyl-1,3-propanediamine, followed by quaternization with sodium choloroacetate of the obtained intermediates. The intermediates and final surfactants were characterized by ¹H NMR and ESI-HRMS, respectively. Krafft temperature (T _K) and surface activities of the surfactants were also examined. It was found that T _K of all these surfactants is lower than 0?°C, and their critical micellar concentration (CMC) is within the range of 10^?3?mmol/L. In addition, the linear relationship between lg CMC and n is still in evidence.     

Biodegradation of nonionic surfactants containing propylene oxide

Insertion of oxypropylene groups into the polyoxyethylene chain of fatty and oxo alcohol ethoxylates decreased the rate and extent of biodegradation. The magnitude of the effects was proportional to the PO-block size and the extent of branching in the alcohol. Data are presented from a series of PO-containing nonionic surfactants in semi-continuous activated sludge reactors over test periods of up to 12 weeks. Bioassays performed on effluents from the SCAS units showed little or no toxicity due to residual degradation metabolities towardPimephales promelas andDaphnia pulex and a stimulatory effect onSelenastrum capricornutum growth rate.     

Preparation,Characterization and Properties of Novel Cationic Gemini Surfactants with Rigid Amido Spacer Groups

A series of novel cationic gemini surfactants with rigid amido groups inserted as the spacers, named C ₁₂ ‐PPDA‐C ₁₂ , C ₁₄ ‐PPDA‐C ₁₄ and C ₁₆ ‐PPDA‐C ₁₆ , were synthesized by a two‐step reaction with dimethyl terephthalate, N,N‐dimethyl propylene diamine and alkyl bromide as raw materials. The chemical structures of the prepared compounds were confirmed by IR, ¹H and ¹³C NMR and element analysis. Surface activity properties of the synthesized compounds were investigated by surface tension, electrical conductivity and fluorescence. Increasing the number of carbon atoms in the hydrophobic alkyl chain, decreased the critical micelle concentration (CMC), surface tension at the CMC and the minimum surface area. Other relevant properties including foaming ability and emulsion stability were investigated. The results indicated that the synthesized gemini surfactants possess good surface properties, emulsifying properties and steady foam properties.     

Undecanoic and 10-Undecenoic Acid-Based Amidobetaines and Amidoamine Oxides

Three types of undecanoic and 10-undecenoic acid-based surfactants were synthesized in the present work: amphoteric amidobetaines, cationic amidobetaine chlorides and nonionic amidoamine oxides. Structural characterizations of synthesized compounds were based on nuclear magnetic resonance (NMR) (¹H and ¹³C) and mass spectrometry. Surface properties, such as critical micelle concentration (CMC), surface tension at cmc (γ _cmc), efficiency of surface adsorption (pC20), surface excess (Γ_max) and minimum area per molecule (A _min) at the air–water interface, were determined by surface tension methods. Fluorescence probing techniques were also employed for the measurement of CMC, as well as steady state anisotropy (r) at the micellar core. The CMC of the studied surfactants follow the order: amidobetaine > amidobetaine chloride > amidoamine oxide. The influence of the terminal double bond in the hydrophobic alkyl chain on CMC was also assessed, and a significant increase in CMC was found due to the introduction of the double bond in the cases of amidobetaine chlorides and amidoamine oxides. These two types of surfactants showed higher rigidity at the micellar core compared to their corresponding unsaturated counterparts. However, such influence of unsaturation on the hydrophobic moiety was not observed in the case of amidobetaines. In all three types of surfactants, the saturated surfactant exhibited a lower γ _cmc and A _min, but higher Γ_max, r and pC20 compared to its unsaturated counterpart.