Alcohol Ethoxysulfates Research Articles

Alcohol ethoxysulfates (AES) in environmental matrices.

Extensive use of surfactants in numerous fields resulted in their discharge into various environmental compartments including soil, sediment, and water. Alcohol ethoxysulfates (AES) together with alcohol ethoxylates (AE), alkyl sulfates (AS), and linear alkyl benzene sulfonates (LAS) find wide variety of applications in consumer products including both domestic and industrial applications. Consequently, all these surfactants pose several concerns to both aquatic and human health. In the context of environmental impacts, AES has almost equal importance as that of LAS though the literature on this topic is only emerging. This review provides a detailed overview on the various aspects of the anionic surfactant, AES, such as toxicity of AES, its fate in the ecosystem, technical advancements in the area of identification and quantification, its occurrence and distribution in different environmental compartments spanning across the world, and finally a remark of its potential removal strategy from the environment.

Identification of surfactants and its correlation with physicochemical parameters at the confluence region of Vembanad Lake in India.

The present study describes the monitoring of some of the major classes of surfactants in water. The separation, identification, and the quantitative estimation of the compounds were achieved using LC-Q-ToF-MS. The analyses revealed the presence of variety of surfactants including linear alkylbenzene sulfonate (LAS), alcohol ethoxysulfates (AES), and alcohol ethoxylates (AE). Further, emphasis was given to AES as they are one of the most produced and consumed surfactants in the world. And as far as India is concerned, the present study is one of the most significant attempt regarding the identification and quantification of AES. The data obtained during the analysis revealed that the average concentration of AES C12Ex varied from 0.7 to 13.6μgL-1 while that of C14Ex ranged between 1.3 and 10.4μgL-1. The risk assessment revealed that higher chain AES are capable of posing medium level risk to the aquatic compartment. In addition, the study also included the physicochemical analysis of water from the selected area. Water was found to be acidic in nature and the salinity, TDS, and EC values were found to be high during the pre-monsoon season. The order of the levels of anionic constituents was of Cl->SO42-SO42->F->NO32- ≅ PO42- while that of cations were Na+>Mg2+>K+>Ca2+. Results of correlation analysis showed that statistically negative correlation exists between AES homologs and pH while slight positive correlations were found between AES and other parameters including TDS and EC. The suitability of this water for domestic and agricultural purposes has been examined on the ground of basic quality indices such as the water quality index (WQI) and sodium adsorption ratio (SAR). The WQI measurements also revealed that the water quality of the region falls under the "very poor" category especially during the pre-monsoon season. The study could explore the cumulative share of these canals in the quality impairment of the receiving Vembanad Lake.

Sorption, degradation and transport phenomena of alcohol ethoxysulfates in agricultural soils. Laboratory studies

In the present work, laboratory studies were conducted in order to determine and model the sorption, degradation and transport processes of alcohol ethoxysulfates (AES), one of the most important groups of anionic surfactants. Adsorption/desorption isotherms were obtained for several structurally related AES ethoxymers (homologue AES-C12En with n = 0–10 ethoxymer units and homologue AES-C14En with n = 0–7 ethoxymer units) using a batch equilibrium method. Data were fitted to a linear and a Freundlich isotherm models. Additionally, experiments in continuous-flow soil columns were also carried out and the breakthrough curves observed for each compound were studied. Breakthrough curves were used to determine the fundamental parameters of the transport model (hydrodynamic dispersion coefficient, degradation rate constant and adsorption/desorption isotherm slope), that is the main phenomena that take place simultaneously when AES move through agricultural soil. When the results obtained for the AES ethoxymers are combined, they reveal a clear and consistent trend towards a sorption increase with the number of ethoxylated units and with the length of the alkyl chain that opens the possibility to estimate the values of the transport parameters for other structurally related ethoxymers.

Evaluation of anionic surfactant concentrations in US effluents and probabilistic determination of their combined ecological risk in mixing zones

Alcohol sulfates (AS), alcohol ethoxysulfates (AES), linear alkyl benzenesulfonates (LAS) and methyl ester sulfonates (MES) are anionic surfactants that are widely used in household detergents and consumer products resulting in over 1 million tons being disposed of down the drain annually in the US. A monitoring campaign was conducted which collected grab effluent samples from 44 wastewater treatment plants (WWTPs) across the US to generate statistical distributions of effluent concentrations for anionic surfactants. The mean concentrations for AS, AES, LAS and MES were 5.03±4.5, 1.95±0.7, 15.3±19, and 0.35±0.13μg/L respectively. Since each of these surfactants consist of multiple homologues that differ in their toxicity, the concentration of each homologue measured in an effluent sample was converted into a toxic unit (TU) by normalizing to the predicted no effect concentration (PNEC) derived from high tier effects data (mesocosm studies). The statistical distributions of the combined TUs in the effluents were used in combination with distributions of dilution factors for WWTP mixing zones to conduct a US-wide probabilistic risk assessment for the aquatic environment for each of the surfactants. The 90th percentile level of TUs for AS, AES, LAS and MES in mixing zones were 1.89×10−2, 2.73×10−3, 2.72×10−2, and 3.65×10−5 under 7Q10 (lowest river flow occurring over a 7day period every 10years) low flow conditions. Because these surfactants have the same toxicological mode of action, the TUs were summed and the aquatic safety for anionic surfactants as a whole was assessed. At the 90th percentile level under the conservative 7Q10 low flow conditions the forecasted TUs were 4.21×10−2 which indicates that there is a significant margin of safety for the class of anionic surfactants in US aquatic environments.

Comprehensive review of several surfactants in marine environments: Fate and ecotoxicity.

Surfactants are a commercially important group of chemicals widely used on a global scale. Despite high removal efficiencies during wastewater treatment, their high consumption volumes mean that a certain fraction will always enter aquatic ecosystems, with marine environments being the ultimate sites of deposition. Consequently, surfactants have been detected within marine waters and sediments. However, aquatic environmental studies have mostly focused on the freshwater environment, and marine studies are considerably underrepresented by comparison. The present review aims to provide a summary of current marine environmental fate (monitoring, biodegradation, and bioconcentration) and effects data of 5 key surfactant groups: linear alkylbenzene sulfonates, alcohol ethoxysulfates, alkyl sulfates, alcohol ethoxylates, and ditallow dimethyl ammonium chloride. Monitoring data are currently limited, especially for alcohol ethoxysulfates and alkyl sulfates. Biodegradation was shown to be considerably slower under marine conditions, whereas ecotoxicity studies suggest that marine species are approximately equally as sensitive to these surfactants as freshwater species. Marine bioconcentration studies are almost nonexistent. Current gaps within the literature are presented, thereby highlighting research areas where additional marine studies should focus.

Effects of Hardness and Cosurfactant on Phase Behavior of Alcohol-Free Alkyl Propoxylated Sulfate Systems

Summary The effect of hardness was investigated on equilibrium phase behavior in the absence of alcohol for blends of three alcohol propoxy sulfates (APSs) with an internal olefin sulfonate (IOS) with a C15–18 chain length. Hard brines investigated were synthetic seawater (SW), 2*SW, and 3*SW, the last two with double and triple the total ionic content of SW with all ions present in the same relative proportions as in SW, respectively. Optimal blends of the APS/IOS systems formed microemulsions with n-octane that had high solubilization suitable for enhanced oil recovery at both ≈25°C and 50°C. However, oil-free aqueous solutions of the optimal blends in 2*SW and 3*SW, as well as in 8 and 12% NaCl solutions with similar ionic strengths, exhibited cloudiness and/or precipitation and were unsuitable for injection. In SW at 25°C, the aqueous solution of the optimal blend of C16–17 7 propylene oxide sulfate, made from a branched alcohol, and IOS15–18, was clear and suitable for injection. A salinity map prepared for blends of these surfactants illustrates how such maps facilitate the selection of injection compositions in which injection and reservoir salinities differ. The same APS was blended with other APSs and alcohol ethoxy sulfates (AESs) in SW at ≈25°C, yielding microemulsions with high n-octane solubilization and clear aqueous solutions at optimal conditions. Three APS/AES blends were found to form suitable microemulsions in SW with a crude oil at its reservoir temperature near 50°C. Optimal conditions were nearly the same for hard brines and NaCl solutions with similar ionic strengths between SW and 3*SW. Although the aqueous solutions for the optimal blends with crude oil were slightly cloudy, small changes in blend ratio led to formation of lower phase microemulsions with clear aqueous solutions. When injection and reservoir brines differ, it may be preferable to inject at such slightly underoptimum conditions to avoid generating upper phase, Winsor II, conditions produced by inevitable mixing of injected and formation brines.

Evaluation of the levels of alcohol sulfates and ethoxysulfates in marine sediments near wastewater discharge points along the coast of Tenerife Island

Alcohol sulfates (AS) and alcohol ethoxysulfates (AES) are all High Production Volume and ‘down-the-drain’ chemicals used globally in detergent and personal care products, resulting in low levels ultimately released to the environment via wastewater treatment plant effluents. They have a strong affinity for sorption to sediments. Almost 50% of Tenerife Island surface area is environmentally protected. Therefore, determination of concentration levels of AS/AES in marine sediments near wastewater discharge points along the coast of the Island is of interest. These data were obtained after pressurized liquid extraction and liquid chromatography–tandem mass spectrometry analysis. Short chains of AES and especially of AS dominated the homologue distribution for AES. The Principal Components Analysis was used. The results showed that the sources of AS and AES were the same and that both compounds exhibit similar behavior. Three different patterns in the distribution for homologues and ethoxymers were found.

Environmental monitoring of alcohol sulfates and alcohol ethoxysulfates in marine sediments

The study describes the environmental monitoring of anionic surfactants-alcohol sulfates (AS) and alcohol ethoxysulfates (AES)-in marine sediments. Concentration values were obtained after pressurised liquid extraction (PLE) and liquid chromatography-tandem mass spectrometry analysis (LC-MS/MS). Samples were collected from a range of wastewater discharge points along the coast of the provinces of Huelva, Málaga, Granada and Almería. Urban, agricultural and industrial wastewaters are discharged at the selected 38 sampling sites. Principal component analysis was carried out in order to evaluate the distribution and behaviour of these compounds in these coastal environments. Evaluation of the data revealed that the behaviour and sources of AS and AES in marine sediments are different, and that the distribution of AES depends on the length of the alkyl chain, while the number of ethoxylated units is not relevant. Additionally, the 38 sampling sites can be grouped into only two types of outfalls according to their AS distribution. The concentration of compounds in sediment samples ranged from 7.52 to 13.50 mg kg(-1) for AS, from 3.04 to 10.68 mg kg(-1) for AES-C12Ex and from 3.83 to 11.56 mg kg(-1) for AES-C14Ex.

Determination of alcohol sulfates and alcohol ethoxysulfates in marine and river sediments using liquid chromatography–tandem mass spectrometry

A novel and successful method has been developed for the identification and quantification of alcohol sulfates (AS) homologues and alcohol ethoxysulfates (AES) ethoxymers in marine and river sediment samples. The method involves the extraction of 5.00g of dry sample with methanol using pressurized liquid extraction (PLE) and liquid chromatography–tandem mass spectrometry (LC–MS/MS). 2-Octylbenzene sulfonic acid sodium salt (2ØC8-LAS) was used as internal standard. The analytical methods were applied to marine sediments collected from the coast of Almeria (South-east Spain) and river sediments collected from the Monachil river (Granada, South-east Spain). For AS homologues, the found limits of detection were 0.04–0.08μgg−1 for marine and river sediments. For AES ethoxymers, the found limits of detection were 0.03–0.09μgg−1 and 0.06–0.22μgg−1 for marine and river sediments, respectively. The highest concentrations of AS and AES were found in river sediment samples. Significant differences were also observed between the behavior of short-chain compounds (C12) and long-chain compounds (C14 to C18). The influence of the physic-chemical properties of water on the occurrence of these compounds was also evaluated, and differences between long- and short-chain compounds were also observed. Additionally, principal components analyses were carried out in order to study the relationship between variables and to evaluate the sources of data variability and behavior patterns. Finally, important conclusions were drawn regarding the environmental behavior of AS and AES.

A new procedure of determination of alcohol sulfates and alcohol ethoxysulfates in agricultural soils

The number of analytical methodologies that focus in the determination of alcohol sulfates (AS) and alcohol ethoxysulfates (AES) in terrestrial environment is very limited. In the present work, a new methodology to improve the extraction and determination of AS and AES in agricultural soil samples has been developed. Prior to instrumental analysis, an extraction procedure using pressurized liquid extraction with methanol (PLE) was carried out in order to obtain the highest recoveries and improve sensitivity. The most influential variables affecting the PLE procedure were optimized. Then, the separation and quantification of analytes were performed by liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). The limits of detection (LOD) ranged from 0.03 to 0.08μgg−1 for AS homologues and in the case of AES ethoxymers from 0.03 to 0.09μgg−1 for AES-C12Ex and from 0.03 to 0.08μgg−1 for AES-C14Ex. Matrix-matched calibration was used. Trueness was evaluated by using a spike recovery assay with spiked blank samples, and the recoveries ranged from 98.3% to 101.0% for AS and from 99.9% to 100.1% for AES. The method was satisfactorily applied in a field study designed to evaluate the environmental behavior of these compounds in agricultural soil.

Determination of alcohol sulfates and alcohol ethoxysulfates in wastewater samples by liquid chromatography tandem mass spectrometry

The work develops a liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for the identification and quantification of alkyl homologues of alcohol sulfates (AS) and ethoxymers of alcohol ethoxysulfates (AES) in wastewaters. The method involves isolation and preconcentration of the analytes from the samples using solid-phase extraction (SPE) with SAX cartridges prior to their quantification by LC–MS/MS with electrospray (ESI) interface in negative mode. The limits of detection (LOD) found were 0.1μgL−1 for AS, and ranged from 0.2 to 0.5μgL−1 for AES. The limits of quantification (LOQ) ranged from 0.3 to 0.4μgL−1 for AS, and from 0.5 to 1.5μgL−1 for AES. The accuracy of the method was studied in terms of trueness and precision. Trueness was evaluated by using a spike recovery assay with spiked blank samples. Recoveries ranged from 96.0 to 102.8% for AS and from 93.4 to 105.1% for AES. Precision (in terms of inter- and intra-day RSD) was lower than 5% for AS and AES. Finally, the method was satisfactorily applied to the quantification of compounds in wastewater samples collected from a wastewater treatment plant (WWTP) located in the city of Granada (Spain). Data obtained showed that AS are present in concentration levels from 0.7 to 39.4μgL−1 in influent waters and from 1.1 to 8.1μgL−1 in effluent waters. As for AES, the amounts (sum of ethoxymers) found ranged from 0.7 to 24.0μgL−1 in influents and from 1.9 to 2.5μgL−1 in effluents.

Practicing IEF‐PAGE of EPO: The impact of detergents and sample application methods on analytical performance in doping control

Electrophoretic techniques, namely isoelectric focusing polyacrylamide gel electrophoresis (IEF-PAGE) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) are key techniques used for confirming the doping-related abuse of recombinant erythropoietins and analogs. IEF-PAGE is performed on horizontal slab-gels with samples applied to the surface of the gel. Different sample application techniques can be employed, but application pieces and applicator strips are most frequently used. However, defective application pieces cause lane streaking during IEF of erythropoietin (EPO), which is especially pronounced in the acidic region of the gel. The effect is due to an incompatibility of the substance used for enhancing the wettability of the cellulose-based commercial product and is batch-dependent. A detailed mass spectrometric study was performed, which revealed that defective sample application pieces (bought between 2007 and 2010) contained a complex mixture of alcohol ethoxylates, alcohol ethoxysulfates, and alkyl sulfates (e.g. SDS). Anionic detergents, like the sulfates contained in these application pieces, are in general incompatible with IEF. Alternative application techniques proved partly useful. While homemade pieces made of blotting paper are a good alternative, the usage of applicator strips or shims is hampered by the risk of leaking wells, which lead to laterally diffused samples. Casting IEF-gels with wells appears to be the best solution, since sustained release of retained proteins from the application pieces can be avoided. Edge effects do not occur if wells are correctly filled with the samples. The evaluation of EPO-profiles with defects is prohibited by the technical document on EPO-analytics (TD2009EPO) of the World Anti-Doping Agency (WADA).

Characterization of alcohol ethoxylates as alcohol ethoxy sulfate derivatives by liquid chromatography‐Mass spectrometry

AbstractThe characterization of alcohol ethoxylates (AE) to determine ethylene oxide (EO) adduct distribution has been studied in our laboratory for many years by using high‐performance liquid chromatography‐mass spectrometry (LC‐MS). This paper describes the LC‐MS approach being used to analyze both nonderivatized and derivatized AE. We conclude that the best way to determine EO adduct distribution is by first converting the AE to alcohol ethoxy sulfates (AES) and then by using LC‐MS with electrospray ionization in the negative ion mode. A convenient laboratory technique for converting small‐scale samples of AE to AES has been discovered and is reported herein. Several examples of EO adduct distribution determined by this method are presented for both linear and isomeric AE samples.

Use of certain alcohol ethoxylates to maintain protease stability in the presence of anionic surfactants

AbstractAnionic surfactants, including linear alkylbenzene sulfonate (LAS), are known to decrease the stability of detergent proteases, possibly by hastening autoproteolytic processes. Thus, protease shelf life in enzyme‐containing, heavy‐duty liquid laundry detergents (HDL) is typically maintained by adding stabilizers, by limiting the level of interfering anionics, or by utilizing more compatible anionics, such as alcohol ethoxysulfates (AES). This study examines the stability of Savinase® detergent protease in HDL formulations based on LAS and containing different alcohol ethoxylates (AE) for protection against protease inactivation. Dose response curves demonstrated that all commonly used anionic surfactants except AES promote loss of protease activity. In HDL formulations with equal percentage compositions of LAS and AE, the structure of the selected AE was found to have a profound influence on protease stability. Inclusion of AE with chain length ≥C14 and ethoxylate levels >70% resulted in greater protease stability. HDL containing LAS and these protective AE could be formulated to achieve protease stability matching those of simulated commercial products. Unlike polyhydric stabilizers, the AE by themselves confer no additional stability to the protease. It is more likely that the stabilizing effect of the “protective” AE is due to decreased availability of LAS to the protease.

Optimization of nonionic/anionic surfactant blends for enhanced oily soil removal

AbstractPreviously reported results for alcohol ethoxylate surfactants have shown that optimum removal of both nonpolar and sebum‐ like liquid soils from polyester/cotton fabric occurs at the phase inversion temperature (PIT) of the surfactant‐ water‐ soil system. A similar correlation between phase inversion and optimum detergency has been identified for detergent systems containing mixtures of nonionic and anionic surfactants such as alcohol ethoxylates and alcohol ethoxysulfates. Experimental techniques other than direct detergency studies are described which allow determination of the optimum nonionic/ anionic surfactant ratio for removal of a particular soil at a specified temperature. In addition, implications of these results for development of temperature‐ insensitive detergent formulations containing alcohol ethoxylates are discussed.

Solvent‐free high active matter alcohol ethoxysulfate/alcohol ethoxylate blends: Preparation and effect of surfactant structure on rheological properties

AbstractBlends of alcohol ethoxysulfates (AES) and alcohol ethoxylates (AE) at high active matter content (90%) have been prepared. These blends contain no solvents other than water and have sufficiently low viscosities enabling the pumping of them from storage vessels to mix tanks. In addition, they may be diluted into aqueous solutions with less gel formation tendencies than shown by AE or AES alone. Specific AE/AES blend ratios, alkyl and polyoxyethylene chain lengths are important selection parameters for achieving desired rheological properties.