Anionic Alkyl Sulfate Research Articles

Simultaneous adsorption of anionic alkyl sulfate surfactants onto alpha alumina particles: Experimental consideration and modeling

Simultaneous adsorption of four anionic alkyl sulfate (AS) surfactants, including sodium octyl sulfate, sodium decyl sulfate, sodium dodecyl sulfate and sodium tetradecyl sulfate named as C8, C10, C12 and C14, onto alpha alumina (α-Al2O3) particles were systematically investigated. Concentrations of all mixtures of anionic AS surfactants in aqueous solution were quantified by capillary electrophoresis coupled with contactless conductivity detection (CE-C4D). Adsorption isotherms of the four anionic AS surfactant homologs increased with either the decrease of pH from 6.0 to 4.0 due to enhancement of electrostatic attractions between the positively charged α-Al2O3 surface and the anionic AS surfactants or the increase of carbon chain length due to enhanced hydrophobic interactions. At different salt concentrations, a common intersection point (CIP) obtained for adsorption isotherms demonstrated that the contributions of electrostatic and hydrophobic interactions were reversed. The ionic strength effect on anionic AS surfactant adsorption isotherms onto α-Al2O3 particles was thoroughly studied. Simultaneous adsorption of the four AS surfactants onto the α-Al2O3was controlled by both electrostatic and hydrophobic interactions that were in accordance with Langmuir and two-step models.

Separation and determination of alkyl sulfate surfactants in wastewater by capillary electrophoresis coupled with contactless conductivity detection after preconcentration by simultaneous adsorption using alumina beads

The aim of the present study is to determine four anionic alkyl sulfate (AS) surfactants with different alkyl chains, namely, C8, C10, C12, and C14, in wastewater by CE with capacitively coupled contactless conductivity detection (CE-C4 D). The conditions effective for the separation of the four AS surfactants were systematically optimized and found to be in a Tris-His (50mM/20mM) BGE solution at a pH of 8.95, using a separation voltage of +15kV, hydrodynamic injection by siphoning using a 20cm injection height and an injection time of 20 s. The LODs for C8, C10, C12, and C14 were 2.58, 2.30, 2.08, and 3.16mg/L, respectively. The conditions used to achieve the simultaneous adsorption and preconcentration of the AS surfactants using Al2 O3 beads were pH of 3 and 0.1mM NaCl. The adsorption efficiencies were found to be 45.6, 50.8, 81.7, and 99.9%, while the desorption efficiencies reached 66.1, 70.4, 83.9, and 100.0% for C8, C10, C12, and C14, respectively. The concentrations of the AS surfactants in wastewater samples were quantified by CE-C4 D after preconcentration by simultaneous adsorption using Al2 O3 beads. The results obtained from the proposed method were consistent with those obtained by HPLC-MS/MS, with a deviation of less than 15%. Our results indicate that the CE-C4 D performed after preconcentration by an adsorption technique using Al2 O3 beads is a new, inexpensive, and suitable method for quantifying AS surfactants in wastewater samples.

Genome-wide identification for genes involved in sodium dodecyl sulfate toxicity in Saccharomyces cerevisiae

BackgroundSodium dodecyl sulfate (SDS) is one of the most widely used anionic alkyl sulfate surfactants. Toxicological information on SDS is accumulating, however, mechanisms of SDS toxicity regulation remain poorly understood. In this study, the relationship between the SDS-sensitive mutants and their intracellular ROS levels has been investigated.ResultsThrough a genome-scale screen, we have identified 108 yeast single-gene deletion mutants that are sensitive to 0.03% SDS. These genes were predominantly related to the cellular processes of metabolism, cell cycle and DNA processing, cellular transport, transport facilities and transport routes, transcription and the protein with binding function or cofactor requirement (structural or catalytic). Measurement of the intracellular ROS (reactive oxygen species) levels of these SDS-sensitive mutants showed that about 79% of SDS-sensitive mutants accumulated significantly higher intracellular ROS levels than the wild-type cells under SDS stress. Moreover, SDS could generate oxidative damage and up-regulate several antioxidant defenses genes, and some of the SDS-sensitive genes were involved in this process.ConclusionThis study provides insight on yeast genes involved in SDS tolerance and the elevated intracellular ROS caused by SDS stress, which is a potential way to understand the detoxification mechanisms of SDS by yeast cells.

Comparison of Electrophoretic Methods for Determination of Critical Micelle Concentration of Anionic Alkylsulfate Surfactants in Water/Organic Environment

The methods for determination of critical micelle concentration of anionic surfactants using capillary electrophoresis instrumentation were compared in this work. We have focused on the determination of critical micelle concentration of homological series of n-alkyl sulfates using four different methods: the electrical current-based method, and method using migration times, retention factors and effective mobilities of n-alkylbenzenes as probe molecules. We have studied the effects of operation conditions (capillary dimensions, applied voltage) and composition of probe samples on the values of critical micelle concentration. The values of critical micelle concentration determined in water and in 25 mmol L−1 borate buffer pH 8.5 without and with addition of 20% (v/v) of acetonitrile ranged from 60 mmol L−1 for sodium nonyl sulfate to 6.1 mmol L−1 for sodium tridecyl sulfate, with higher values for electrolyte containing acetonitrile. The concentration and solvent of probe molecules have significant effect on the determined value of critical micelle concentration. We have studied in detail critical micelle concentration of sodium dodecyl sulfate in mixtures with low concentration of acetonitrile up to the 6% (v/v). In this region, higher uncertainty of determination of critical micelle concentration was experienced.

Fluorescent LDPE and PLA nanocomposites containing fluorescein-modified layered double hydroxides and their ON/OFF responsive behavior towards humidity

We report on the preparation and characterization of fluorescent polymer nanocomposites based upon poly(lactic acid) (PLA) or linear low density polyethylene (LDPE) filled with 5 wt% of fluorescein-modified layered nanoparticles. Modified layered double hydroxide (LDH) nanoparticles were prepared by co-intercalation of fluorescein and alkyl sulfate anions thus yielding to three hybrid samples having different lambda of emission and quantum yield, depending on fluorophore content and presence of dye aggregates. Further separation of Flu aggregates by dispersion of less fluorescent co-intercalated LDHs in PLA and LDPE resulted in an increase of the quantum yield, with better results for PLA-based nanocomposites in agreement with a better morphology. Preliminary data indicated the possible use of these materials as ON/OFF humidity indicators.

Bis-imidazolium salts with alkyl sulfates as counterions: synthesis and liquid crystalline properties

A series of flexibly linked bis-imidazolium salts with alkyl sulfate anions having different chain lengths (10, 12, 14) was investigated for their thermotropic behavior.

New principals on the adsorption of alkyl compound by Mg–Al oxide: Adsorption kinetics and equilibrium studies

The uptake of ethylsulfate (ES−), hexylsulfate (HS−), and dodecylsulfate (DS−) anions by Mg–Al oxide in aqueous solution was examined through adsorption equilibrium and kinetic modelling. The removal of ES−, HS−, and DS− by Mg–Al oxide proceeded as diffusion-controlled reactions exhibiting Langmuir-type adsorption isotherms. The maximum amounts of adsorption are ordered as DS−>HS−>ES−. Mg–Al oxide preferentially reacts with the organic anion with lower charge density, because the effect of hydrophobic interactions in these cases is stronger than that of electrostatic interactions. In the first stage of reaction, Mg–Al oxide, which is prepared by the thermal decomposition of Mg–Al layered double hydroxides (LDHs) intercalated with CO32− (CO3·Mg–Al LDH), rehydrates and combines with alkylsulfate to reconstruct the LDH structure. Then the alkylsulfate anions intercalated in the interlayer of the LDH attracted other anions in the solution via hydrophobic interactions, thereby promoting their removal by Mg–Al oxide. DS− was removed with the highest efficiency followed by HS−, because the hydrophobic attraction between DS− anions is stronger than that between HS−, which is stronger than that between ES−. At low initial concentrations (C0), the intercalated alkylsulfates are likely oriented parallel to the brucite-like host layers of Mg–Al LDH. With increasing C0, pairs of alkyl chains in DS− and HS− may overlap due to the hydrophobic interaction, while the alkyl chains in DS− are likely arranged perpendicular to the host layers to form bilayers.

Toxicity of nanoparticle surface coating agents: Structure-cytotoxicity relationship

ABSTRACTSurface coating agents for metal nanoparticles, cationic alkyl ammonium bromides, and anionic alkyl sulfates were tested against human skin keratinocytes (HaCaT) and blood T lymphocytes (TIB-152). The surfactants of short chain (C8) are not cytotoxic, but as chain length increases, their cytotoxicity increases and levels off at C12 for cationic surfactants against both cell lines and for anionic surfactants against the TIB-152, but C14 for anionic surfactants against HaCaT. The cationic surfactants are more toxic than the anionic surfactants for HaCaT; while with similar cytotoxicity for TIB-152 cells. di- and tetra-Alkyl ammonium salts are more cytotoxic than the mono-substituted.

Influence of hydrophobicity of alkyl sulfate and alkylpyridinium surfactants on the transport characteristics of plasticized polyvinyl chloride membranes

The ion transport of homologues of alkyl sulfate anions and alkylpyridinium cations through polyvinyl chloride filtration membranes (molecular sieves) under the conditions of diffusion mass transfer and direct current has been investigated. The quantitative characteristics of membrane transport, such as the permeability, diffusion, and partition coefficients; ion flux, selectivity, sorption capacity, and recovery, have been calculated. The effect of the hydrocarbon radical length of ionic surfactants on the quantitative characteristics of membrane transport has been revealed. It has been found that molecular sieves can be used for the separation of surfactant homologues.

Redox-Induced Ion Pairing of Anionic Surfactants with Ferrocene-Terminated Self-Assembled Monolayers: Faradaic Electrochemistry and Surfactant Aggregation at the Monolayer/Liquid Interface

Oxidoreduction of self-assembled monolayers (SAMs) of ferrocenyldodecanethiolate on gold in aqueous solutions of surface-active sodium n-alkyl sulfates (NaCnSO4) of 6, 8, 10, and 12 carbons is investigated by cyclic voltammetry and surface plasmon resonance. The effects of surfactant micellization and alkyl chain length on the redox response of the surface-tethered ferrocenes are examined. The SAM redox electrochemistry is sensitive to the surfactant aggregation state in solution. The nonideal behavior of the sodium alkyl sulfates at concentrations above the critical micelle concentration leads to a non-Nernstian variation of the SAM redox potential with concentration. The presence of micelles in solution results in decreased anodic-to-cathodic peak separations and anodic peak full widths at half-maximum. A longer alkyl chain length results in an increased ability of the alkyl sulfate anion to ion pair with the SAM-bound ferrocenium, resulting in oxidation of the ferrocene at lower potential. A comparison of the SAM redox potential at a fixed surfactant concentration of ideal behavior suggests a 4.5 × 10(4) difference in the ion-pairing abilities of the shorter-chain C6SO4(-) and longer-chain C12SO4(-). One-half of the available SAM-bound ferrocenes are oxidized in the NaCnSO4 electrolyte. Surfactant anions adsorb and assemble onto the SAM surface by specific ion-pairing interactions between the sulfate headgroups and oxidized ferrocenium species, forming an interdigitated monolayer in which the surfactant anions alternate between a heads-down and heads-up orientation with respect to the SAM. The work presented points to applications of ferrocenylalkanethiolate SAMs as anion-selective membranes, probes of micelle formation, and surfaces for the electrochemically switchable assembly of organosulfates.

Salt-free catanionic surface active ionic liquids 1-alkyl-3-methylimidazolium alkylsulfate: Aggregation behavior in aqueous solution

A series of salt-free catanionic surface active ionic liquids (SAILs), 1-alkyl-3-methylimidazolim alkyl sulfates (denoted as [Cnmim][CmSO4], n=6, 8, 10; m=12 and n=4; m=10, 14) were synthesized by an ion exchange reaction and their surface properties in aqueous solution were examined systematically by surface tension, fluorescence and electrical conductivity measurements. As catanionic surfactants, these SAILs exhibit notably higher surface activity, compared to the cationic or anionic analogues. Increment in both cationic and anionic alkyl chain lengths for [Cnmim][CmSO4] can both improve the amphiphilic character remarkably. This can be ascribed to cooperative interactions as formation of catanionic pairs between alkyl-substituted imidazolium cations and alkyl sulfate anions. The negative micellization Gibbs free energy values prove that the micellization of all the 1-alkyl-3-methylimidazolim alkyl sulfates investigated is a spontaneous process. Any additional CH2 group makes the micellization process easier regardless if it is on a cation or an anion. When keeping the total carbon atom number constant, we find that the [Cnmim][CmSO4] molecules with greater asymmetric alkyl chains display superior surface activity. This work indicates that the self-assembly of these imidazolium-based salt-free catanionic SAILs can be tailored by adjusting the mismatch of alkyl chains. These SAILs are expected to have potential applications in the fields of colloidal and interface and nanomaterial synthesis.

Are Alkyl Sulfate-Based Protic and Aprotic Ionic Liquids Stable with Water and Alcohols? A Thermodynamic Approach

The knowledge of the chemical stability as a function of the temperature of ionic liquids (ILs) in the presence of other molecules such as water is crucial prior to developing any industrial application and process involving these novel materials. Fluid phase equilibria and density over a large range of temperature and composition can give basic information on IL purity and chemical stability. The IL scientific community requires accurate measurements accessed from reference data. In this work, the stability of different alkyl sulfate-based ILs in the presence of water and various alcohols (methanol, ethanol, 1-butanol, and 1-octanol) was investigated to understand their stability as a function of temperature up to 423.15 K over the hydrolysis and transesterification reactions, respectively. From this investigation, it was clear that methyl sulfate- and ethyl sulfate-based ILs are not stable in the presence of water, since hydrolysis of the methyl sulfate or ethyl sulfate anions to methanol or ethanol and hydrogenate anion is undoubtedly observed. Such observations could help to explain the differences observed for the physical properties published in the literature by various groups. Furthermore, it appears that a thermodynamic equilibrium process drives these hydrolysis reactions. In other words, these hydrolysis reactions are in fact reversible, providing the possibility to re-form the desired alkyl sulfate anions by a simple transesterification reaction between hydrogen sulfate-based ILs and the corresponding alcohol (methanol or ethanol). Additionally, butyl sulfate- and octyl sulfate-based ILs appear to follow this pattern but under more drastic conditions. In these systems, hydrolysis is observed in both cases after several months for temperatures up to 423 K in the presence of water. Therein, the partial miscibility of hydrogen sulfate-based ILs with long chain alcohols (1-butanol and 1-octanol) can help to explain the enhanced hydrolytic stability of the butyl sulfate- and octyl sulfate-based ILs compared with the methyl or ethyl sulfate systems. Additionally, rapid transesterification reactions are observed during liquid-liquid equilibrium studies as a function of temperature for binary systems of (hydrogen sulfate-based ionic liquids + 1-butanol) and of (hydrogen sulfate-based ionic liquids + 1-octanol). Finally, this atom-efficient catalyst-free transesterification reaction between hydrogen sulfate-based ILs and alcohol was then tested to provide a novel way to synthesize new ILs with various anion structures containing the alkyl sulfate group.

Solubility of gases in 1-alkyl-3methylimidazolium alkyl sulfate ionic liquids: Experimental determination and modeling

The solubility of different gases (carbon dioxide, methane, ethane, carbon monoxide and hydrogen) in ionic liquids with an alkyl sulfate anion has been modeled with the Group Contribution equation of state developed by Skjold-Jørgensen. New gas solubility measurements have been carried out with a high pressure magnetic suspension balance in order to cover pressure and temperature ranges not considered in previous studies and to obtain more experimental information for the correlation of parameters of the equation of state. New solubility measurements include the solubility of carbon dioxide in 1-ethyl 3-methyl imidazolium ethyl sulfate [emim][EtSO4] at temperatures of 298K and 348K and pressures ranging from 0.3MPa to 6.5MPa, the solubility of methane in [emim][EtSO4] at a temperature of 293K and pressures ranging from 0.2MPa to 10.2MPa, and the solubility of ethane in [emim][EtSO4] at temperatures of 323K and 350K and pressures ranging from 0.2MPa to 4MPa. Results show that the Group Contribution equation of state can be used to describe the solubility of gases in alkyl sulfate ionic liquids as well as infinite dilution coefficients of alkanes in the ionic liquids, with average deviations between experiments and calculations ranging from 1% to 10% in the case of mixtures with CO2, CO, CH4 and H2 with the alkyl sulfate ionic liquids to up to 34% in the case of the solubility of ethane in [emim][EtSO4].

Aqueous-Biamphiphilic Ionic Liquid Systems: Self-Assembly and Synthesis of Gold Nanocrystals/Microplates

Biamphiphilic ionic liquids (BAILs) based on 1,3-dialkylimidazolium cation and alkyl sulfate anions ([C(n)H(2n+1)mim][C(m)H(2m+1)OSO(3)]; n = 4, 6, or 8; m = 8, 12) have been synthesized and characterized for their self-assembling behavior in the aqueous medium. Effects of alteration of alkyl chain length in cation and anion on surfactant properties of BAILs have been examined from surface tension measurements. The effectiveness of surface tension reduction for BAILs has been found to be exceptionally higher as compared to single chain surface active ILs/conventional surfactants. The thermodynamics of the aggregation process has been studied using isothermal titration calorimetry (ITC) and temperature dependent conductivity experiments. Dynamic light scattering (DLS), nuclear magnetic resonance (NMR), and transmission electron microscopy (TEM) studies showed that BAILs formed distinct aggregated structures depending upon the amphiphilic character present in the cation and anion. BAILs ([C(n)H(2n+1)mim][C(m)H(2m+1)OSO(3)]) form micelles when n = 4, 6; m = 8, intermicellar aggregates when n = 4, 6; m = 12, and vesicles when n = 8; m = 8, 12. Gold nanoparticles and microplates have been synthesized in micellar and vesicle solutions of BAILs using a simple photoreduction method. The studies show the potential of BAILs for constructing micelles and supramolecular assemblies, such as bilayer vesicles, which are effective in preparation of nanomaterials of controlled size and morphology.

Interaction of Levitated Ionic Liquid Droplets with Water

The influence of a humid or dry atmosphere on acoustically levitated ionic liquid droplets was studied by volumetric analysis and vibrational spectroscopy. Imidazolium-based ionic liquids with two types of anions, fluorinated (BF(4) and PF(6)) and alkylsulfate anions, were investigated. The amount of absorbed water was correlated with structural differences of the ionic liquids and analyzed in terms of equilibrium mole fraction as well as absorption rate. The type of anion had the most significant influence on the amount of adsorbed water from the atmosphere. Furthermore, spectral changes in the in situ Raman spectra due to absorbed water were studied for all investigated ionic liquids. For 1-ethyl-3-methylimidazolium ethylsulfate, an exemplary detailed analysis of the intermolecular interactions between cations, anions and water was carried out based on the spectroscopic data. The observed band shifts were explained with a hydrogen bond between the anion and water.

An efficient and green approach to prepare hydrophilic imidazolium ionic liquids free of halide and its effect on oxygen reduction reaction of Pt/C catalyst

An efficient process to prepare basic imidazolium ionic liquids (ILs) solution free of halide has been developed based on the rapid ion exchange between alkyl sulfate anion (ROSO3−, R=alkyl) and OH− in ethanol. Eight halide-free ILs with a flexible range of cations and anions were prepared by neutralizing the basic IL solution with corresponding acids. The viscosity, ionic conductivity or melting points of the ILs obtained by present method were examined and discussed. The results implied that the whole process is green since only ethanol and water were used as solvents and by-products were only solid KROSO3 and KY (Y=desired anion). Furthermore, a typical imidazolium ionic liquid, [Emim]HSO4, was synthesized by different precursors with various amounts of Br impurity, and its effect oxygen reduction reaction (ORR) of Pt/C catalyst was systematically investigated.

Alkylsulfate-based ionic liquids in the liquid–liquid extraction of aromatic hydrocarbons

The (liquid + liquid) equilibrium data (LLE) for the extraction of toluene from heptane with different ionic liquids (ILs) based on the alkylsulfate anion (R-SO 4) was determined at T = 313.2 K and atmospheric pressure. The effect of more complex R-SO 4 anions on capacity of extraction and selectivity in the liquid–liquid extraction of toluene from heptane was studied. The ternary systems were formed by {heptane + toluene + 1,3-dimethylimidazolium methylsulfate ([mmim][CH 3SO 4]), 1-ethyl-3-methylimidazolium hydrogensulfate ([emim][HSO 4]), 1-ethyl-3-methylimidazolium methylsulfate ([emim][CH 3SO 4]), or 1-ethyl-3-methylimidazolium ethylsulfate ([emim][C 2H 5SO 4])}. The degree of quality of the experimental LLE data was ascertained by applying the Othmer–Tobias correlation. The phase diagrams for the ternary systems were plotted, and the tie lines correlated with the NRTL model compare satisfactorily with the experimental data.

Apparent molar volumes and expansivities of aqueous solutions of ionic liquids, l-alkyl-3-methylimidazolium alkyl sulfate at T = (298.15–328.15) K

Densities of some aqueous ionic liquids containing alkyl sulfate anions, 1-ethyl-3-methylimidazolium methyl sulfate, 1-hexyl-3-methylimidazolium methyl sulfate, and 1-hexyl-3-methylimidazolium ethyl sulfate solutions were measured at T=(298.15–328.15)K and at atmospheric pressure. The apparent molar volumes at infinite dilution were found by extrapolation to infinite dilution with using Redlich–Mayer and Pitzer equations. The apparent molar volumes at infinite dilution were used to obtain information about solute–solvent and solute–solute interactions. The temperature dependence of apparent molar volumes were used to calculation of apparent molar expansivities and the Hepler's constant values, (∂2Vϕ0/∂T2)P. The Hepler's constant values were found very small negative which indicating the ionic liquids under study are predominantly a structure breaker due to hydrophobic hydration of ionic liquids in water. The results were discussed in terms of alkyl chain length and anion size on the volumetric properties on the studied ionic liquids.

Alkyl Sulfonate Functionalized Ionic Liquids: Synthesis, Properties, and Their Application in Esterification

Ionic liquids based on alkyl sulfate anions and alkyl sulfonate functionalized cations were prepared from commercially available and cheap materials and their thermal-instability properties were studied in detail. These ionic liquids were active catalysts for esterification and they gave moderate to high yields. The catalytic performance was found to be much better than that of conventional non-cation functionalized ionic liquids and close to sulfonic acid functionalized ionic liquids. The catalytic process in this reaction was investigated by electrospray ionization mass spectrometry and a plausible reaction mechanism is suggested. ：采用廉价易得的原料合成了阳离子含有烷基磺酸酯官能团的功能化离子液体, 并考察了其热稳定性. 该离子液体可催化羧酸的酯化反应, 其催化活性高于阳离子非功能化的离子液体, 而与磺酸功能化离子液体相当. 同时采用电喷雾电离质谱考察了该离子液体在酯化反应中的作用. We investigated methyl sulfonate-functionalized ionic liquids and found that they are excellent catalysts for esterification. The sulfonic acid group formed by the hydrolysis of methyl sulfonate is proposed to be the most important catalytic center.

Glycine-based ionic liquids as potential electrolyte for electrochemical studies of organometallic and organic redox couples

Ten ionic liquids (ILs) based on glycine cations with bis(trifluoromethanesulfonyl)amide or alkylsulfate anions as novel electrolytes are prepared and evaluated. The ILs exhibit wide electrochemical windows of 5.0 V and good ionic conductivity (up to 1.44 mS cm − 1 at 35 °C). The Stokes–Einstein products of two organometallic redox couples, Fc/Fc + (ferrocene/ferrocenium) and Cc/Cc + (cobaltocene/cobaltocenium), and an organic redox couple TMPD (N,N,N′,N′-tetramethyl-para-phenylenediamine) in the ILs are determined. The solvodynamic radii of Fc, Cc, and TMPD are found to be independent of the types of ILs.