催化动力学光度法测定阴离子表面活性剂

基于在H2SO4介质中,阴离子表面活性剂对高碘酸钠氧化罗丹明B褪色的反应具有较强的催化作用,建立了测定阴离子表面活性剂的催化动力学光度法.本文以十二烷基硫酸钠为标准品进行实验,线性范围为0.08～0.20 mg/L,检出限为0.0193 mg/L.用于水样中阴离子表面活性剂总量的测定,测定结果的相对标准偏差为1.3%～1.4%,回收率为104%～106%.     

Determination of non-ionic and anionic surfactants in environmental water matrices

Solid-phase extraction (SPE) combined with liquid chromatography electrospray mass spectrometry (LC-(ESI)MS) was used to determine 16 non-ionic and anionic surfactants in different environmental water samples at ng L⁻¹ levels. The proposed method is sensitive and simple and has good linear range and detection limits (less than 50 ng L⁻¹) for most compound classes.The effect of ion suppression was studied in aqueous matrices from several treatment plants—including urban and industrial wastewater treatment plants (WWTPs), drinking-water treatment plants (DWTPs) and seawater desalination plants (SWDPs)—and it was considered when quantifying our samples. In addition, conventional treatments and tertiary treatments that use advanced membrane technologies, such as ultrafiltration (UF) and reverse osmosis (RO) were evaluated in order to determine their efficiency in eliminating these compounds.The concentrations of non-ionic surfactants in the raw waters studied ranged from 0.2 to 100 μg L⁻¹. In effluents, the concentrations ranged from 0.1 to 5 μg L⁻¹, which reflects consistent elimination. Anionic surfactants were present in all waters studied at higher levels. Levels up to 3900 μg L⁻¹ of linear alkylbenzene sulfonates (LASs) and 32,000 μg L⁻¹ of alkyl ethoxysulfates (AESs) were detected in urban WWTP influents, while levels up to 25 μg L⁻¹ of LASs and 114 μg L⁻¹ of AESs were found in drinking-water and desalination treatment plants.The results indicate that conventional processes alone are not sufficient to completely remove the studied surfactants from waste streams. Tertiary treatments that use advanced membrane technologies such as UF and RO can further reduce the amount of target compounds in the effluent water.     

Determination of trace inorganic anions in anionic surfactants by single-pump column-switching ion chromatography

An ion chromatography method has been proposed for the determination of three common inorganic anions(chloride,nitrate and sulfate) in anionic surfactants using a single pump system.The new system consists of an ion exclusion column,a concentrator column,and an anion exchange column connected in series via two 6-ports valves in a Dionex ICS-2000 ion chromatograph.The valves were switched several times for removing surfactants,concentrating and separating the three anions.The chromatographic conditions were optimized.Detection limits(S/N = 3) were in the range of 0.10-0.68μg/L.The relative standard deviations(RSDs) of peak area were less than 4.6%.The recoveries were in the range of 84.1-112.6%.     

Sorption-photometric determination of anionic surfactants in water

The adsorption of Crystal Violet, anionic surfactants, and their ion associates on nonionic hydrophobic polymer adsorbent Amberlite XAD-16 was studied. A procedure for the sorption-photometric determination of anionic surfactants in water was developed with a detection limit of 0.001–0.003 mg/L at a sample volume of 50 mL.     

Determination of sulphate content of anionic surfactants: sodium di-2-ethylhexyl sulphosuccinate

A simple nephelometric method for the determination of sulphates in the anionic surfactant Aerosol-OT is described. The method is based on the formation and stabilization of a barium sulphate dispersion in a water-alcohol mixture and measurement of the turbidity at 650 nm. Beer's law is followed for sodium sulphate concentrations in Aerosol-OT ranging from 0 to 7000 microg/g. The lower determination limit is about 100-200 microg/g and the reproducibility about 5% for typical commercial Aerosol-OT samples. The method can also be used for other anionic surfactants by adjusting the water-ethanol ratio of the solvent.     

Synthesis of anionic sulphonate-crown ether surfactants

Two sulphonate-crown ether surfactants （sodium （4＇-dodecanoyldJbenzo-18-crown-6）-4＂（5＂）-sulpho- nate, ammonium （4＇-dodecanoyldibenzo-18-crown-6）-4＂（5＂）-sulphonate） were designed and synthesized via a two-step continuous method. The products were purified and characterized by IR. 1H NMR and elemental analysis. The physicochemical properties of the surfactants were studied by fluorescence, conductivity and dynamic light scattering techniques.     

Interactions of anionic surfactants with methemoglobin

The liquid crystal morphologies of symmetrical diacy phosphatidylcholine liposomes examined in this research study were found to be dependent on saturated hydrocarbon chain length. Both powder X-ray diffraction and synchrotron mid-IR spectromicroscopy indicate that phosphatidylcholines with short hydrocarbon tails (i.e. ten and twelve carbons) are more likely to form unilamellar liposomes while those with long hydrocarbon tails (i.e. eighteen and twenty carbons) are more likely to form multilamellar liposomes. Hydrocarbon chain lengths of fourteen and sixteen represent a transitional zone between these two liquid crystal morphologies. The FTIR spectra where a shoulder develops on the peak at wavenumber 1750 cm(-1) particularly highlights the change in the packing of adjacent molecules in the transitional zone.     

Electrocapillary potentiometric determination of anionic surfactants in detergents

Summary An attempt has been made to use electrocapillarity for potentiometric determinations of anionic surfactants. A sitting mercury drop indicator electrode was successfully used for these titrations. Anionic surfactants should be titrated in a solution of defined ionic strength (0.8% sodium sulphate) at any pH between 3 and 10. A cationic surfactant (Hyamine 1622) should be used as the titrant. Pure anionic surfactants, technical grade anionic surfactants and anionic surfactants in model detergents have all been successfully titrated.

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Elektrokapillare Potentiometrie anionischer Tenside

Zusammenfassung Der Elektrokapillareffekt wurde zur potentiometrischen Bestimmung anionischer Tenside auszunutzen versucht. Als Indikatorelektrode wurde mit Erfolg eine J-förmige Hg-Elektrode (Elektrode mit aufsitzendem Hg-Tropfen) benutzt. Die Titration anionischer Tenside wird in einer Lösung bestimmter Ionenstärke (0,8% Natriumsulfat) und im pH-Bereich 3–10 durchgeführt. Als Titrant verwendet man dazu ein kationisches Tensid (Hyamin 1622). Reine anionische Tenside, technische anionische Tenside und anionische Tenside in einem Modellwaschmittel wurden titriert.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

The interaction of an anionic gemini surfactant with conventional anionic surfactants

The interaction in two mixtures of an anionic gemini surfactant having N ,N -dialkylamide and carboxylate groups in a molecule, (CH2)2[N(COC11H23)CH(CO2H)CH2(CO2H)]2. 2NaOH (GA), and conventional anionic surfactants have been investigated in 0.1 M NaCl at pH 5.0. The two mixtures are GA/sodium dodecylsulfate (SDS) and GA/sodium N -dodecanoylglutamate (AGS) at a molar fraction of GA, alphaGA = 0.25 . Mixtures of both GA/SDS and GA/AGS exhibit synergism in surface tension reduction effectiveness. The GA/SDS mixture also exhibits synergism in surface tension reduction efficiency and mixed micelle formation, whereas the GA/AGS mixture does not. The interaction in mixed adsorption film formation is stronger than that in mixed micelle formation for the two mixtures. The interaction in the formation of the mixed adsorption film and the mixed micelle for the GA/SDS mixture is stronger in both formations than that for the GA/AGS mixture. The stronger interaction for the GA/SDS mixture may be caused by the combination of the smaller minimum area per molecule at the air/water interface (Amin) of the head groups in the GA molecule and the larger Amin in the SDS molecule.     

Studies on the electrocapillary curves of anionic surfactants in presence of non-ionic surfactants

Polyoxyethylated non-ionic surfactants such as Tween 20, Tween 40, Nonidet P40 and Nonex 501 have been supposed to be associated with cationic characteristics. Studies on the effect of these surfactants on the electrocapillary curves of the anionic surfactants Aerosol IB, Manaxol OT and sodium lauryl sulphate (SLS), show that the electrocapillary maxima shift towards positive potentials. The order of adsorption of the anionic surfactants is SLS > Manaxol OT > Aerosol IB while the shift in maxima is in the order Aerosol IB ~ Manaxol OT > SLS which confirms association of cationic characteristics with the micelles of these non-ionic surfactants. The magnitude of the shift in electrocapillary maxima is Nonex 501 > Nonidet P40 > Tween 20 > Tween 40 which may be the order of magnitude of the positive charge carried by these non-ionic surfactants.     

Methods for the determination of anionic surfactants

Methods for the determination of synthetic anionic surfactants published in the past two decades are considered, and their advantages and disadvantages are demonstrated. Spectrophotometric and potentiometric (with the use of ion-selective electrodes) techniques, including flow injection analysis versions, are used for the determination of anionic surfactants. Chromatographic techniques (primarily, high-performance liquid chromatography) are most frequently used for the separation, preconcentration, and determination of anionic surfactants in complex mixtures. Spectrofluorimetry, voltammetry, and immunoassay did not find wide application.     

The interaction of anionic surfactants with gelatin

The binding of sodium dodecyl sulfate and a hydrophilic color coupler anion to gelatin was investigated using a surfactant-selective electrode. The binding isotherms of the surfactants to an alkali-processed bone gelatin, as well as an acid-processed bone gelatin were determined and compared with viscosity data.The comparison shows that viscosity measurements can only be regarded as circumstantial evidence for binding. At nearly identical binding isotherms the viscosity curves were found to be very different.     

Extraction preconcentration with anionic surfactants in acidic solutions

Extraction preconcentration with anionic surfactants in acidic solutions on the basis of the cloud point was studied. Advantages and disadvantages of this method were considered. Conditions of the phase separation of some anionic surfactants (sodium decyl sulfate, sodium dodecyl sulfate, sodium dodecyl sulfonate, and sodium dodecylbenzene sulfonate) in acidic solutions were studied. With the example of pyrene and its derivatives, it was demonstrated that these surfactants can be used for extraction preconcentration. Analytical characteristics of the determination of pyrene and its derivatives in model aqueous solutions by the fluorimetric method in combination with extraction preconcentration with sodium dodecyl sulfate were obtained     

Physicochemical properties of anionic triple-chain surfactants in alkaline solutions

A series of novel gemini cationic surfactants alkanediyl-alpha,omega-bis (hydroxyethylmethylhexadecylammonium bromide) with polymethylene spacer chain length of 4, 6, 8, and 10 carbon atoms was synthesized and characterized. Critical micellar concentrations of the gemini surfactants in aqueous solutions as determined by the surface tension and conductance measurements were observed to be in the range 1.39-3.63 microM. The critical micellar concentration was observed to increase initially with spacer length up to 6 methylene groups and to decrease thereafter with the increase in spacer length. The micellar microstructure in aqueous solutions examined through small angle neutron scattering (SANS) revealed that the extent of aggregation growth and variation in shapes of micelles strongly depend on head group polarity, spacer chain length, and temperature. The propensity to micellar growth with spacer chain length 4 was found to be much higher than with the longer spacer lengths. The fractional charge on the micelle increases with increased spacer chain length and temperature.     

Determination of aggregation thresholds of UV absorbing anionic surfactants by frontal analysis continuous capillary electrophoresis

Aggregation of anionic surfactants was investigated by frontal analysis continuous capillary electrophoresis (FACCE), a method involving the continuous electrokinetic introduction of the surfactant sample into the separation capillary. This process results in a partial separation of the monomeric and aggregated forms without perturbing the monomer-aggregate equilibrium. The critical micelle concentration (CMC) can then be easily derived from the height of the firstly detected migration front, corresponding to the monomeric form. This approach is exemplified with octyl and dodecylbenzenesulfonates and compared with conductimetry and surface tension measurements. FACCE turns out to be an effective method for the determination of CMC and intermediate aggregation phenomena with very small sample and short time requirements.     

Mixed micelles of homologous perfluoropolyether anionic surfactants in water

The mixtures of sodium and ammonium salts of three homologous perfluoropolyether carboxylic acids having Cl-terminated perfluoroalkyl group (Cl-PFPE) and differing in the average molecular weight (MW) were examined. The surfactants, namely n2, n3 and n4, have two, three and four PFPE units, respectively. Each surfactant was studied alone and in mixture with the other surfactants with the same counterion. NMR chemical shifts were measured for each surfactant and for the mixtures in different concentrations. For a given mixture the micelle composition, X_i, can be determined from the observation of the chemical shifts of the micellar components. It was found that Cl-PFPE surfactant mixtures form in water mixed micelles which contain the surfactants in equilibrium with monomeric species. The analysis of NMR chemical shift variations allowed evaluating the partition of the various surfactants in the mixed aggregates as a function of the total concentration. Composition of mixed micelles resembles ideal mixing predictions particularly at high surfactant concentrations.     

Interactions between cationic starch and anionic surfactants

The surface tensions and the phase equilibria of dilute aqueous cationic starch (CS)/surfactant systems were investigated. The degree of substitution of the CS varied from 0.014 to 0.772. The surfactants investigated were sodium dodecyl sulphate (SDS), potassium octanoate (KOct), potassium dodecanoate (KDod) and sodium oleate (NaOl). The concentrations of CS were 0.001, 0.01 and 0.1 w%.Critical association concentrations (cac) occur at surfactant concentrations well below the critical micelle concentrations of the surfactants, except for KOct, KDod and NaOl at the lowest CS concentrations investigated (0.001 w%). The surface tensions of CS/surfactant solutions decrease strongly already below the cac. This is attributed to the formation of surface active associates by ion condensation. Associative phase separation of gels formed by CS and surfactant takes place at extremely low concentrations when the surfactant/polymer charge ratio is somewhat larger than 1. The gel is higly viscous and contains 40–60% water, depending on the concentration of electrolyte, the surfactant hydrocarbon chain length and the nature of the polar head of the surfactant.The concentration at which the phase separation occurs decreases with increasing surfactant chain length and the concentration of simple electrolyte, factors that promote micelle formation. This indicates that the gels are formed by association of CS to surfactant micelles. When surfactant well in excess of charge equivalence is added, the gels dissolve because the CS/surfactant complexes acquire a high charge.     

Threadlike micelle formation of anionic surfactants in aqueous solution

We have investigated the formation of threadlike micelles consisting of anionic surfactants and certain additives in aqueous solution. Threadlike micelles long enough to be entangled with each other were formed in a clear aqueous solution of two anionic surfactants, sodium hexadecyl sulfate and sodium tetradecyl sulfate. These solutions also contained pentylammonium bromides or p-toluidine halides and exhibited remarkable viscoelasticity. Because the molar ratio of surfactants to cationic additives in these micelles seemed close to unity, they formed 1:1 stoichiometric complexes between surfactant anions and additive cations, as previously found in systems of cationic surfactants such as hexadecyltrimethylammonium bromide and sodium salicylate. The viscoelastic behavior of these anionic threadlike micellar systems was adequately described by a simple Maxwell element with a single relaxation time and strength, as in many similar cationic systems.     

A new ion-selective electrode for anionic surfactants

The new ligand 7-methyl-7,13-di-octyl-1,4,10-trioxa-13-aza-7-azonia-cyclopentadecane (L¹) has been designed, synthesised and used as ionophore in the development ion-selective electrodes for anionic surfactants. Different PVC-membrane anionic-surfactants-selective electrodes were prepared by using L¹ as ionophore and bis(2-ethylhexyl)sebacate (BEHS), dibutyl phthalate (DBP) and nitrophenyl octyl ether (NPOE) as plasticizers. The PVC-membrane electrode containing L¹ and NPOE (electrode E1) showed a Nernstian response to lauryl sulfate with a slope of −59.5 mV per decade in a range of concentrations from 1.3 × 10⁻⁶ to 6.8 × 10⁻³ M and a detection limit of 6.0 × 10⁻⁷ M. The electrode E1 also showed a reasonable response to other alkyl sulfates and alkylbenzene sulfonates, whereas it does not respond to carboxylates and to cationic and non-ionic surfactants. A similar electrode to E1 but additionally containing the cationic additive n-octylammonium bromide was also prepared (electrode E2) and compared with the response of E1. Selectivity coefficients for different anions with respect to lauryl sulfate were determined by means of the fixed interference method considering lauryl sulfate as the principal anion and using a concentration of 1.0 × 10⁻² mol dm⁻³ for the corresponding interfering anion. The selectivity sequence found for the electrode E1 was: LS⁻ > SCN⁻ > ClO₄⁻ > CH₃COO⁻ > I⁻ > HCO₃⁻ > Br⁻ > NO₃⁻ > NO₂⁻ > Cl⁻ > IO₃⁻ > phosphate > SO₃²⁻ > C₂O₄²⁻ > SO₄²⁻. Electrode E1 showed remarkably better selectivity coefficients than electrode E2.