Linear Alcohol Ethoxylate Surfactant Research Articles

Bilayer to micelle transition of DMPC and alcohol ethoxylate surfactants as studied by isoperibol calorimetry

The interaction of dimyristoylphosphatidylcholine (DMPC) with non-ionic surfactants has been studied using isoperibol calorimetry. Phospholipid-surfactant systems were formed in the isoperibol calorimeter with varying amounts of surfactant and the change in enthalpy on formation was measured. Solubilization of the phospholipid lamellae was assessed as a decrease in the enthalpy of reaction of co-films containing DMPC and increasing amounts of three linear alcohol ethoxylate surfactants: C10H21(OCH2CH2)3OH, C10H21(OCH2CH2)5OH, or C12H25(OCH2CH2)7OH. The isoperibol calorimetry data for DMPC/surfactant/water systems were consistent with a theoretical three-stage model for the solubilization of phospholipids by surfactants, whereby phospholipid bilayers are transformed into mixed micelles with increasing amounts of surfactant. The results indicate that: (i) the interaction between phospholipid and surfactants results in a non-linear correlation between the enthalpy of reaction and the surfactant concentration; (ii) the structural stage of the lamellar to micelle transition (mixed bilayers, mixed micelles, or both) can be determined from calorimetric data; (iii) phase boundaries in the solubilization process (bilayer saturation, micelle saturation) can be identified as break points in the enthalpy-concentration curve; and (iv) increasing the hydrophilicity of the surfactant results in a decrease of the surfactant concentration producing the onset of solubilization.

A stream mesocosm study on the ecological effects of a C12?15 linear alcohol ethoxylate surfactant*1

A stream mesocosm study on the ecological effects of a C12?15 linear alcohol ethoxylate surfactant*1

A stream mesocosm study on the ecological effects of a C 12–15 linear alcohol ethoxylate surfactant

The responses of fish, invertebrates, and periphyton during a 56-day exposure to a C 12–15 linear alcohol ethoxylate surfactant were studied in stream mesocosms. An individual stream consisted of a slow-flowing pool section and a faster-flowing riffle section. The surfactant has an average distribution of nine ethoxylate groups per mole of alcohol. Eight stream mesocosms were used to test the effects of seven concentrations of the surfactant. Time-averaged, mean, measured concentrations were 20, 40, 70, 160, 300, 390, and 740 μg/L, which represented 70–100% of nominal concentrations. The exposure of aquatic communities to the C 12–15AE-9 surfactant in stream mesocosms resulted in no-observed-effect concentrations (NOECs) for individual endpoints ranging from 160 to 740 μg/L. Among the more sensitive responses were Oncorhynchus mykiss time to swim up and fry growth, abundance of juvenile Gammarus pulex in drift samples, Baetis abundance in the riffle sediment and in samples collected from tiles placed in the riffle, and Simulium density in the riffle tiles, all with NOECs of 160 μg/L. Responses of the riffle sediment invertebrate assemblages assessed using multivariate methods support a NOEC of 160 μg/L. Abundances of G. pulex, Copepoda, and Agapetus sampled in the pools and pool tiles were not affected at the highest surfactant concentration tested after 56 days. Surfactant effects on periphyton and community leaf processing were seen at 300–390 μg/L. Based upon the responses of several taxa representing different trophic levels, a mesocosm NOEC of 160 μg/L can be stated for the C 12–15AE-9 surfactant. This study provided additional data that can be used to reduce the uncertainty in extrapolating laboratory data to the field for the environmental risk assessment of alcohol ethoxylates.

Quinclorac Efficacy as Affected by Adjuvants and Spray Carrier Water1

Laboratory and greenhouse experiments were conducted to determine quinclorac efficacy as influenced by surfactants, methylated seed oil (MSO), basic pH compounds, and salts in the spray carrier water. Quinclorac efficacy for green foxtail control generally increased with an increase in linear alcohol ethoxylate (LAE) surfactant carbon-chain length and percentage of ethoxylation. With LAE surfactants, quinclorac phytotoxicity to green foxtail was nearly doubled (average from 44 to 81%) when triethanolamine (TEA) was included in the spray mixture. Combination of LAE surfactants with TEA also enhanced quinclorac absorption. Enhancement of quinclorac absorption and phytotoxicity by LAE surfactants and TEA was related to spray deposits that had close contact with the cuticle and without apparent quinclorac crystals. Sodium and calcium ions strongly antagonized quinclorac efficacy when applied with a block copolymer surfactant or MSO. Ammonium sulfate or ammonium nitrate adjuvants were more effective than urea–...

Optimizing Alcohol Ethoxylate Surfactant Activity at Low Doses

Certain linear alcohol ethoxylate surfactants with large hydrophobes enhanced nicosulfuron activity on giant foxtail (Setaria faberi) more effectively at low doses than surfactants with small hydrophobes and commercial standards. The most effective surfactants had a C16–18 hydrophobe and 12 to 30 moles of ethoxylation or a C24 hydrophobe with 13 moles of ethoxylation. Response curve analysis showed these linear alcohol ethoxylate surfactants were five- to 20-fold more active on a dose basis than currently used commercial surfactants.

Effects of a homologous series of linear alcohol ethoxylate surfactants on fathead minnow early life stages.

Effects of a homologous series of three primarily linear alcohol ethoxylate surfactants were studied in laboratory flow-through 28-day early-life-stage tests with fathead minnow (Pimephales promelas Rafinesque). Surfactants were a C(9-11), C(12-13), and C(14-15) with an average of 6, 6.5, and 7 ethylene oxide units per mole of alcohol, respectively. Average measured surfactant recoveries were 103%, 81%, and 79% of nominal concentrations for the C(9-11) EO 6, C(12-13) EO 6.5, and C(14-15) EO 7 studies, respectively. Embryo survival at 48 h was not adversely affected at any of the concentrations tested. Impaired hatching and deformed fry were observed only in the C(12-13) EO 6.5 study. The 28-day LC50 values were 4.87, 2.39, and 1.02 mg/L for the C(9-11) EO 6, C(12-13) EO 6.5, and C(14-15) EO 7 surfactants, respectively. The corresponding NOECs for survival were 1.01, 1.76, and 0.74 mg/L. Posthatch fry growth was more sensitive than survival for the C(12-13) EO 6.5 and C(14-15) EO 7 surfactants. Survival of posthatch fry decreased with increasing surfactant alkyl chain length. Twenty-eight-day laboratory data were compared to 96-h laboratory, 10-day laboratory and 30-day stream mesocosm data for fathead minnow previously determined for these surfactants. Survival endpoints from the different exposures were comparable and only varied within a factor of two. Similarity of results suggests that it is possible to effectively use 96-h, 10-day, or 28-day laboratory data to predict environmental effects concentrations of these surfactants for fish. http://link.springer-ny. com/link/service/journals/00244/bibs/37n4p536.html</++ +HEA

Chronic toxicity of a homologous series of linear alcohol ethoxylate surfactants toDaphnia magna in 21 day flow-through laboratory exposures

The chronic toxicity to Daphnia magna Straus in 21 day flow-through laboratory exposures was assessed for a homologous series of nonionic linear alcohol ethoxylate surfactants. Three primarily linear alcohol ethoxylate surfactants with alkyl chain distributions of C9-11, C12-13, and C14-15, and with respective average ethoxymer groups of 6, 6.5, and 7 were tested. Mean measured surfactant exposure concentrations agreed with nominal concentrations, with average recoveries of 93, 84, and 86% (R2=0.99, 0.99, and 0.98) for the C9-11EO6, C12-13EO6.5, and C14-15EO7 surfactants, respectively. Daphnia magna survival 21 day EC50s were 5.9, 2.2 and 1.2 mg L−1 for the C9-11, C12-13, and C14-15 surfactants, respectively. Data indicate a twofold increase in toxicity in terms of daphnid survival with each two carbon addition in alkyl chain length. Daphnid survival and reproduction were equally sensitive for the C9-11 and C14-15 surfactants, however, reproduction was more sensitive than survival for the C12-13 surfactant. Survival NOECs were 2.77, 1.75, and 0.79 mg L−1 while reproduction no observed effect concentrations (NOECs) were 2.77, 0.77, and 0.79 mg L−1 for the C9-11, C12-13, and C14-15 surfactants, respectively. For the surfactants studied, chronic laboratory NOECs for D. magna survival (21 day) were similar to NOECs obtained for cladoceran densities in stream mesocosm experiments (30 day exposures) indicating a direct relationship between laboratory chronic effects and field effect levels for similar organisms. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 293–300, 1999

Chronic toxicity of a homologous series of linear alcohol ethoxylate surfactants to Daphnia magna in 21 day flow‐through laboratory exposures

The chronic toxicity to Daphnia magna Straus in 21 day flow-through laboratory exposures was assessed for a homologous series of nonionic linear alcohol ethoxylate surfactants. Three primarily linear alcohol ethoxylate surfactants with alkyl chain distributions of C9-11, C12-13, and C14-15, and with respective average ethoxymer groups of 6, 6.5, and 7 were tested. Mean measured surfactant exposure concentrations agreed with nominal concentrations, with average recoveries of 93, 84, and 86% (R2=0.99, 0.99, and 0.98) for the C9-11EO6, C12-13EO6.5, and C14-15EO7 surfactants, respectively. Daphnia magna survival 21 day EC50s were 5.9, 2.2 and 1.2 mg L−1 for the C9-11, C12-13, and C14-15 surfactants, respectively. Data indicate a twofold increase in toxicity in terms of daphnid survival with each two carbon addition in alkyl chain length. Daphnid survival and reproduction were equally sensitive for the C9-11 and C14-15 surfactants, however, reproduction was more sensitive than survival for the C12-13 surfactant. Survival NOECs were 2.77, 1.75, and 0.79 mg L−1 while reproduction no observed effect concentrations (NOECs) were 2.77, 0.77, and 0.79 mg L−1 for the C9-11, C12-13, and C14-15 surfactants, respectively. For the surfactants studied, chronic laboratory NOECs for D. magna survival (21 day) were similar to NOECs obtained for cladoceran densities in stream mesocosm experiments (30 day exposures) indicating a direct relationship between laboratory chronic effects and field effect levels for similar organisms. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 293–300, 1999

Responses of Aquatic Invertebrates to a Linear Alcohol Ethoxylate Surfactant in Stream Mesocosms

Responses of aquatic invertebrates to 30-day exposures to a nonionic linear alcohol ethoxylate (LAE) surfactant (C12–13AE-6.5) were evaluated in 10 outdoor stream mesocosms. Responses were measured as changes in invertebrate densities and invertebrate drift densities during a 14-day pretreatment period, a 30-day treatment period, and a 14-day posttreatment period relative to untreated control stream densities. Mean measured surfactant concentrations in duplicate streams were 0.32, 0.88, 1.99, and 5.15 mg LAE/liter, with two streams serving as untreated controls. Statistically significant effects were observed on simulid, copepod, and cladoceran population densities during the treatment period. Based on these effects, the no-observed-effect concentration (NOEC) for invertebrate densities was <0.32 mg LAE/liter and the lowest-observed-effect concentration (LOEC) was 0.32 mg LAE/liter. No statistically significant differences due to treatment were detected in drifting invertebrates; however, a trend was observed with increased numbers of invertebrates drifting in the streams treated with 5.15 mg LAE/liter as compared with controls.

Sorption of linear alcohol ethoxylate surfactant homologs to soils

Sorption onto five saturated soils of the homologs within the commercial surfactant mixture Brij 35 (registered trademark of ICI Americas) was investigated. Brij 35 is a mixture of linear ethoxylated alcohols, having an average of 23 ethoxy (EO) groups per molecule and alcohol chain of primarily 12 carbons in length (C 12H 25(OCH 2CH 2) 23OH). In experiments, saturated soils were exposed to various concentrations of the surfactant mixture for specified times, the slurries were centrifuged to separate the phases, the aqueous phases were extracted with 1,2-dichloroethane, and the residual homologs were derivatized with 3,5-dinitrobenzoyl chloride and analyzed by normal phase HPLC. Homologs containing 4–43 EO groups were chromatographically separated at near baseline. At aqueous Brij 35 concentrations below the critical micelle concentration (cmc), the proportion of each homolog sorbed to each of the soils increased with increasing EO chain length through the homologous series. As a result, in experiments where a significant proportion of the surfactant adsorbed, significant shifts in the aqueous phase compositions occurred to mixtures with lower mean EO numbers. A sharp break in the adsorption isotherms occurs at the cmc.

The effects of a C12–13 linear alcohol ethoxylate surfactant on periphyton, macrophytes, invertebrates and fish in stream mesocosms

AbstractThe ecological effects of a C12–13 linear alcohol ethoxylate (LAE) were studied in stream mesocosms. The surfactant has an average distribution of six and one‐half ethylene oxide groups per mole of alcohol. Responses of periphyton, macrophytes, invertebrates, and fish were examined and used to estimate a mesocosm‐predicted no‐observable‐effect concentration (NOEC). The stream mesocosm experiment consisted of a 2‐week period of natural colonization, a 30‐d treatment period, and a 2‐week post‐treatment period. Four surfactant concentrations in duplicate streams were used along with two untreated control streams. Surfactant concentrations were delivered to the streams with no apparent loss during the 17‐min transit time. The structural integrity of the surfactant was also maintained with no observed differences between the head, middle, or tail sections of individual streams. Average measured concentrations of LAE for replicate streams were 0.32, 0.88, 1.99, and 5.15 mg/L. Periphyton and Myriophyllum aquaticum did not show significant effects. The no‐observed‐effect concentration (NOEC) for all periphyton and M. aquaticum parameters was 5.15 mg/L, the highest concentration tested. Statistically significant effects were observed on Simuliidae, Copepoda, and Cladocera densities during the treatment period in all exposure concentrations. Thus, the lowest‐observed‐effect concentration (LOEC) for invertebrate densities was 0.32 mg/L. Drifting invertebrates did not show significant LAE effects; however, increased numbers of invertebrates drifted in the 5.15‐mg/L streams compared to controls. The 30‐d LC50 for farm‐raised and University‐cultured fathead minnows was similar at 1.27 mg/L. The 30‐d survival NOEC and LOEC for both populations of fish were 0.88 mg/L and 1.99 mg/L, respectively. There were no significant effects on reproduction in University‐cultured fathead minnow. Fathead minnow reproductive behavior and feeding behavior were most susceptible to surfactant exposure with a NOEC of 0.32 mg/L. Bluegill sunfish survival responded similarly to the LAE as fathead minnow with a 30‐d NOEC of 0.88 mg/L. No sublethal effects on juvenile bluegill growth were observed in this study. For primarily regulatory purposes, a “mesocosm NOEC” of 0.28 mg/L was derived for use in risk assessment.

An assessment of the ecological effects of a C9--11 linear alcohol ethoxylate surfactant in stream mesocosm experiments

The responses of stream mesocosm communities to a linear alcohol ethoxylate (LAE) surfactant were studied to (i) assess the relationship between laboratory and field-scale tests; (ii) develop NOECs for responding taxa; and (iii) provide data to develop an aquatic risk assessment for alcohol ethoxylates. The LAE was a mixture of C9--11 linear alcohols with an average of six ethylene oxide (EO) units per mole of alcohol. Twelve stream mesocosms were used to test the effects of five concentrations of the LAE on periphyton, aquatic macrophytes, invertebrates and fish during a 30-day exposure. Vascular plants were unaffected at 11.4 mg L−1, the highest surfactant concentration tested, but various periphyton parameters were altered at lower concentrations. The effects on periphyton were attributed to grazing by resident invertebrates. Invertebrate densities were affected at LAE concentrations above 2.0 mg L−1. Fathead minnows were particularly sensitive to LAE with a NOEC of 0.73 mg L−1 for egg production and larval survival. Bluegill were less sensitive than fathead minnows, with a NOEC for survival and growth of 5.7 mg L−1. The stream mesocosm results for fish and invertebrates were similar to those obtained using laboratory single-species tests

Acute, Subchronic, and Reproductive Toxicity of a Linear Alcohol Ethoxylate Surfactant in the Rat

The mammalian toxicity of a C9–11 linear primary alcohol 6-mole ethoxylate, used in aqueous cleaning formulations, has been evaluated. The rat acute oral LD50 was 1.4 g/kg, and the rabbit acute dermal LD50 was greater than 2 g/kg. Undiluted material was severely irritating to the skin, but a 1% w/v aqueous dilution was not a skin sensitizer. There was no evidence of mutagenicity in the Ames assay. In a rat dermal subchronic study, there were no treatment-related effects at 1% and 10% aqueous concentrations, but at 25%, there was flaking of the skin and microscopic evidence of hyperkeratosis at the treatment site as the only compound-related effect. Potential reproductive toxicity was evaluated in a two-generation study in Fischer rats exposed similarly to the subchronic study. No compound-related effects on the reproductive performance or on the growth and development of the offspring were detected. It is concluded that this ethoxylate is typical of the more widely used alcohol ethoxylates with alkyl chains in the C12–18 range, being moderately acutely toxic by the oral route. By the dermal route—the relevant route of human exposure—it is not expected to produce skin irritation or systemic or reproductive toxicity at concentrations used in formulated cleaning products.