Surfactant Sodium Decyl Sulfate Research Articles

Properties of Micellar Solutions of Sodium Decyl Sulfate at Relatively High Concentrations

Heat capacities of aqueous solutions of anionic surfactant sodium decyl sulfate in the 0.28–0.42 mol kg−1 range of molar concentrations and the 278–363 K range of temperatures are studied via precision adiabatic differential scanning microcalorimetry. Specific and apparent heat capacities of solutions at intervals of 0.01 mol kg−1, partial molar heat capacities of the solute and the solvent, and excess partial molar heat capacities are plotted as functions of concentration and temperature. The Kraft boundary is determined. Analysis of the characteristic changes in the above properties reveals structural changes in sodium decyl sulfate micelles that correspond to their shape transforming from cylindrical to plate-like in the region of the third critical micelle concentration.

Surface rheology and its relation to foam stability in solutions of sodium decyl sulfate

The anionic surfactant sodium decyl sulfate (SDeS) at concentrations below its critical micellar concentration (cmc) was studied in a surface chemically purified state at the air–water interface in terms of its static and dynamic interfacial properties. Equilibrium surface tension was determined using a pendant drop tensiometer. An oscillating bubble capillary pressure tensiometer allowed accessing the surface dilatational properties of the surfactant's adsorption layers in a frequency range from 2 to 500Hz. The estimation of single foam lamella stability was obtained from visual observation of films formed within a rectangular glass frame in a saturated atmosphere. Upon increasing surfactant concentration, the foam lamellae were found to rupture at prolonged lifetimes. The dramatic difference in foam stability goes along with a pronounced transition from a surface elastic to a surface visco-elastic state of the adsorption layers. These findings were indicative for a correlation between foam lamella stability and surface viscoelasticity also for this model surfactant. These results may be of importance to further shed light on the processes governing foam and foam lamella stability.

Effect of Acetonitrile and N,N-Dimethylformamide on the Formation of Poly(ethylene oxide)-Sodium Alkyl Sulfate Aggregates

The effects of low contents of acetonitrile (AN) or N,N-dimethylformamide (DMF) on the aggregation of sodium alkyl sulfate surfactants, in the absence and presence of poly(ethylene oxide) (PEO), were investigated using conductivity and isothermal titration calorimetry. The cosolvents slightly changed the critical micellar concentrations and did not alter the critical aggregation concentrations of the surfactants sodium decyl sulfate (DSS) and sodium dodecyl sulfate (SDS) with PEO. However, AN and DMF turned the micellization of the surfactants and their binding to the polymer enthalpically more favorable. For instance, for SDS, the micellization enthalpy, ΔHomic, decreased from close to 0 kJ mol-1 in water to -14.3 kJ mol-1 in the presence of 2.50 mol% AN, and the integral enthalpy change for aggregate formation with the polymer, ΔHagg(int), decreased from -1.1 kJ mol-1 in water to -15.5 kJ mol-1 in the same AN concentration. This was attributed to the modification of the solvation shells of both SDS and PEO by the cosolvent molecules, which reduced the entropic contribution to formation of the aggregates. Consequently, when SDS was replaced with DSS, the AN affected ΔHomic to a lesser extent, with a decrease of 9.1 kJ mol-1, while the ΔHagg(int) values were not altered, highlighting the influence of hydrophobic interactions in the surfactant aggregation process.

Photo Catalytic Applications of Zinc Oxide Nanorods for the Analysis of Chlorimuron Herbicide Residues in Water by LC-MS/MS

Photo Catalytic Applications of Zinc Oxide Nanorods for the Analysis of Chlorimuron Herbicide Residues in Water by LC-MS/MS Zinc oxide (ZnO) nanorods having the size 100 to 250 nm diameters and 1 to 2 μm length were used as photo-catalyst for the decontamination of sulfonylurea urea herbicide chlorimuron in water. The study was conducted in milli Q water, at three different buffer solutions of pH 4.0, 7.0 and 9.0 under direct sunlight at two different concentrations. The optimum concentration of catalyst required for the complete degradation was established as 0.1 g l-1. The degradation of herbicide in neutral pH water was faster when compared with acidic and basic pH solutions in presence of ZnO catalyst. The influence of cations (Fe2+, Cu2+ and Ni2+) anions (ClO4-, Cl-, CO32-) had shown no significant degradation, but Fe2+ contributed positively to the degradation. Influence of surfactant was studied with cetyltrimethylammonium bromide (CTAB), sodium decyl sulfate (SDS) and Brij-35. The presence of surfactant SDS showed slight increase in the degradation rate. Residues, breakdown products were quantified and confirmed by liquid chromatography electro spray tandem mass spectrometry (LC-ESI-MS/MS). The method has the limit of quantification 0.1 μg/L in water. The dissipation of residues showed first order kinetics, DT 50 and DT 90 were calculated from the dissipation data.

Subsurface Transport Potential of Perfluoroalkyl Acids at Aqueous Film-Forming Foam (AFFF)-Impacted Sites

Subsurface transport potential of a suite of perfluoroalkyl acids (PFAAs) was studied in batch sorption experiments with various soils and in the presence of co-contaminants relevant to aqueous film-forming foam (AFFF)-impacted sites. Specifically, PFAA sorption to multiple soils in the presence of nonaqueous phase liquid (NAPL) and nonfluorinated AFFF surfactants was examined. This study is the first to report on sorption of perfluorobutanoate (PFBA) and perfluoropentanoate (PFPeA) (log Koc = 1.88 and 1.37, respectively) and found that sorption of these compounds does not follow the chain-length dependent trend observed for longer chain-length PFAAs. Sorption of PFBA was similar to that of perfluorooctanoate (PFOA, log Koc = 1.89). NAPL and nonfluorinated AFFF surfactants all had varying impacts on sorption of longer chain (>6 CF2 groups) PFAAs. The primary impact of NAPL was observed in low foc soil (soil A) where Freundlich n-values increased when NAPL was present. Impacts of nonfluorinated AFFF surfactants varied with surfactant and soil. The anionic surfactant sodium decyl sulfate (SDS) illicited PFAA chain-length dependent impacts in two negatively charged soils with varying foc. In soil A, Kd values for perfluoroheptanoate (PFHpA) increased 91% with SDS, whereas values for perfluorodecanoate (PFDA) increased only 28%. An amphoteric surfactant, n,n-dimethyldodecylamine n-oxide (AO), had the most notable impact on PFAA sorption to a positively charged soil (soil C). In this soil, AO oxide significantly increased sorption for the longer chain PFAAs (i.e., 528% increase in Kd for PFDA). Changes in sorption caused by SDS and AO may be due to mixed hemimicelle formation, competitive sorption, or changes to PFAA solubility. Short-chain PFAA behavior in the presence of NAPL, SDS, and AO was again notable. Co-contaminants generally increased the sorption of these compounds to all soils. Log Kd values of PFBA in soil A increased 85%, 372%, and 32% in the presence of NAPL, SDS, and AO, respectively. Use of Kd values to calculate retardation factors (Rf) of PFAAs demonstrates the variability of co-contaminant impacts on PFAA transport. Whereas NAPL and nonfluorinated surfactants decreased the sorption of perfluorooctanesulfonate (PFOS) at lower PFOS concentrations (1 μg/L), they led to increases in sorption at higher PFOS concentrations (500 μg/L). These results demonstrate that PFAA groundwater transport will depend on the solid phase characteristics as well as PFAA concentration and chain length. Detailed site-specific information will likely be needed to accurately predict PFAA transport at AFFF-impacted sites.

Dielectric Spectroscopy Investigation on the Interaction of Poly(diallyldimethylammonium chloride) with Sodium Decyl Sulfate in Aqueous Solution

The interaction between poly(diallyldimethylammonium chloride) (PDADMAC) and ionic surfactant sodium decyl sulfate (C(10)SO(4)Na) in aqueous solution was investigated by means of dielectric relaxation spectroscopy. To better understand the interaction, the dielectric behaviors of PDADMAC solution and C(10)SO(4)Na solution were also separately studied. For PDADMAC solution, two relaxations were observed, which were attributed to the polarization of loosely bound counterions along the directions parallel and perpendicular to the PDADMAC chain. For C(10)SO(4)Na solution, dielectric relaxation was observed at submicellar concentrations, which is ascribed to the counterion diffusion around premicelles. For the aqueous solutions of a PDADMAC/C(10)SO(4)Na mixture with different C(10)SO(4)Na concentrations, three surfactant concentration regions characterized by different dielectric behaviors were observed. The dielectric behavior in different regions was discussed through comparing it with that of PDADMAC solution and C(10)SO(4)Na solution. The possible interaction pattern and microstructure of the PDADMAC/C(10)SO(4)Na complex were proposed on the basis of the dielectric behavior.

A Study of the Behavior of α-Cyclodextrin with Single Solutions of Hydrogenated and Fluorinated Surfactants and Their Mixtures

The interactions between α-cyclodextrin (α-CD) and an equimolar mixture of the anionic hydrogenated and fluorinated surfactants sodium decyl sulfate (SDeS) and sodium perfluorooctanoate (SPFO), res...

Effect of terbium(III) chloride on the micellization properties of sodium decyl- and dodecyl-sulfate solutions

The effect of TbCl 3 on the aggregation processes of the anionic surfactants sodium decyl sulfate (SDeS) and sodium dodecyl sulfate (SDS) has been investigated. Electrical conductivity data, combined with Tb(III) luminescence measurements suggest that the formation of micelles involving TbCl 3 and SDS occurs at concentrations below the critical micelle concentration (cmc) of the pure surfactants; the formation of these mixed aggregates was also monitored by light scattering, which indicates that the addition of TbCl 3 to surfactant concentration at values below the pure surfactant cmc results in a much greater light scattering than that found with pure sodium alkylsulfate surfactant micelles. This phenomenon is dependent upon the alkyl chain length of the surfactant. With Tb(III)/DS −, complexes are formed with a cation/anion binding ratio varying from 3 to 6, which depends upon the initial concentration of Tb(III). This suggests that the majority of the cation hydration water molecules can be exchanged by the anionic surfactant. When the carbon chain length decreases, interactions between surfactant and Tb(III) also decrease, alterations in conductivity and fluorescence data are not so significant and, consequently, no binding ratio can be detected even if existing. The surfactant micellization is dependent on the presence of electrolyte in solution with apparent cmc being lower than the corresponding cmc value of pure SDS.

Interaction between cationic, anionic, and non-ionic surfactants with ABA block copolymer Pluronic PE6200 and with BAB reverse block copolymer Pluronic 25R4

The interaction in aqueous solution between either the normal block copolymer poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide): Pluronic PE6200 [(EO) 11–(PO) 28–(EO) 11], or the reverse block copolymer poly(propylene oxide)–poly(ethylene oxide)–poly(propylene oxide): Pluronic 25R4 [(PO) 19–(EO) 33–(PO) 19] and the surfactants sodium decylsulfate, C 10OS, decyltrimethyl ammonium bromide, C 10TAB, and pentaethylene glycol monodecyl ether, C 10E 5, was investigated and the aggregation behavior of these surfactants with Pluronics was compared. Surface tension measurements show that Pluronics in their non-aggregated state better interact with the anionic surfactant C 10OS than with cationic and non-ionic ones. The presence of the two Pluronics induces the same lowering of the aggregation number of C 10OS as shown by fluorescence quenching measurements. The number of polymer chains necessary to bind each C 10OS aggregate has been estimated to be ∼6 for PE6200 and ∼2 for 25R4. Furthermore, this surfactant also induces the same increment in the gyration radius of the polymers as revealed by viscosimetry. Calorimetric results have been reasonably reproduced by applying a simple equilibrium model to the aggregation processes.

Investigation of the force–distance relationship for a small liquid drop approaching an adhesive liquid/liquid interface

We have used a novel apparatus to investigate the forces between two liquid surfaces which are mutually attractive. An oil drop is formed at the tip of a thin flexible micropipette and the force exerted on the oil drop as it is pressed up to an oil/water interface is determined from the vertical deflection of the pipette shaft. The disjoining pressure in the thin, oil–water–oil emulsion film, formed by contact of the drop with the oil/water interface, is determined by the hydrostatic pressure applied to the oil contained in the micropipette. The radius and the thickness of the film are derived from the optical interference pattern observed using a microscope. A theory is presented for the variation in force and film radius as the drop is moved up to and down from the interface. Experimental results are given for dodecane–water–dodecane emulsion films stabilised by the anionic surfactant sodium decyl sulfate (SDS) in the presence of different aqueous phase concentrations of NaCl, which modifies the attractive force between the monolayers. Data for the force and film radius as a function of the pipette position relative to the oil–water monolayer show qualitative agreement with theoretical predictions. It is shown that differences between theory and experiment are not due to the existence of a line tension at the perimeter of the thin emulsion film formed as the oil drop is pressed up to the oil/water interface. Discrepancies between theory and experiment may be due to imperfect ‘pinning’ of the three-phase contact line at the inner diameter of the micropipette.

Ultrasonic Relaxation and Electrochemical Studies of the Micellization of Sodium Decyl Sulfate and Decyltrimethylammonium Bromide in Glycerol/Water Mixtures

An ultrasonic relaxation has been found in solutions of the surfactants sodium decyl sulfate and decyltrimethylammonium bromide in various glycerol/water mixtures. By using membrane electrodes selective to these surfactants, their critical micellar concentrations and also the monomer surfactant concentrations in micellar solutions have been evaluated. The relaxation has been attributed to the perturbation of the equilibrium between surfactant monomer and micelle. The combined relaxation/electrochemical data have been analyzed to investigate the kinetics of this process, using the Aniansson and Wall and Teubner equations and a phenomenological approach developed in this laboratory.

Effects of surfactant adsorption and biodegradability on the distribution of bacteria between sediments and water in a freshwater microcosm

A microcosm containing resuspended river sediment was used to investigate the effect of anionic surfactants on the distribution of bacteria between planktonic and attached populations. Freshwater river sediment containing viable bacteria was preequilibrated in the microcosm, which was subsequently supplemented with biodegradable or recalcitrant surfactants and a non-surface-active carbon and energy source. Population dynamics of both free-living and attached bacteria were measured by epifluorescence microscopy with simultaneous analysis of the residual solution concentration of the xenobiotic carbon source. The addition of the readily biodegradable anionic surfactants sodium decyl sulfate and sodium dodecyl sulfate in separate experiments caused an increase in the number of attached bacteria and a concomitant decrease in the number of free-living bacteria. As biodegradation of the surfactants progressed, these trends reversed and the bacterial populations had returned to their preaddition values by the time when biodegradation was completed. In contrast, sodium tetradecyl sulfate or sodium dodecane sulfonate did not stimulate bacterial association with sediment, nor were they biodegraded in the microcosm. Sodium pyruvate, a non-surface-active carbon and energy source, was readily utilized but caused no bacterial attachment to the sediment. These results indicate that for an anionic surfactant to induce bacterial attachment to river sediment, it must be biodegradable. The bacterial attachment to the sediment appears to be reversible and may be dependent on the accumulation of the surfactant at the surface or as a result of alteration of the surface free energies.