Dodecylammonium Chloride Research Articles

Adsorption studies of dodecylamine at the quartz interface using an electrode-separated piezoelectric sensor

The adsorption process of dodecylammonium chloride (DAC) from aqueous solutions onto a quartz crystal interface was investigated in situ using an electrode-separated piezoelectric sensor (ESPS). Increasing amounts of DAC adsorbed onto a quartz crystal surface resulted in linearly decreasing oscillating frequencies of the ESPS. The adsorption density can be monitored by the frequency decrease. The adsorption density obtained by calculation using the Sauerbrey equation in the ESPS method is greater than that in solution depletion method. A calibration coefficient is added into the Sauerbrey equation to correct the influence of surface roughness of the quartz crystal on the adsorption density. The influence of solution properties on the adsorption density measurement was discussed. A dependence of the adsorption density on pH was reported.

Thermodynamic Consideration of Mixtures of Surfactants in Adsorbed Films and Micelles

The thermodynamic relations describing the equilibrium between the bulk solution and the adsorbed film were derived for two-component surfactant mixtures that do not share common ions. The mean activity coefficients in the adsorbed film, which can be estimated experimentally, were introduced and proven to comprise a factor attributable to the preferential adsorption of ions. The excess Gibbs energy of adsorption was defined by using the mean activity coefficients and the composition of adsorbed film. The equation of ideal mixing of two components in the adsorbed film was also derived. The analogous equations were developed with respect to the equilibrium between the bulk solution and the micelles. The equations derived were shown to be easily converted to those for ionic–ionic surfactant mixtures with common ions, and ionic–nonionic and nonionic–nonionic surfactant mixtures. Furthermore, the equations were utilized for examining the miscibility of surfactants in the decylammonium bromide (DeAB)–dodecylammonium chloride (DAC), decylammonium chloride (DeAC)–DAC, and DeAB–DeAC mixtures.

Investigation of Langmuir monofilms and flotation experiments with anionic/cationic collector mixtures

The purpose of the paper is to present the result of combined application of anionic collectors such as sodium N-dodecanoyl sarcosine and sodium dodecanate, both of which are improved by use of cationic additional reagents, e.g. alkylammonium chloride, as co-collectors within the flotation of fluorite. The use of sodium N-dodecanoyl sarcosine in combination with dodecylammonium chloride shows synergistic effect in flotation efficiency. Moreover, adsorption of the anionic collector at the liquid/air interface is influenced by cationic surfactants as could be demonstrated by investigations of Langmuir films at the air–water interface. Amine incorporation in floating sarcosine monofilms has a great stabilization effect and the final amine content in the mixed film is related to the maximum in flotation recovery.

Miscibilities of methanol and ethanol with dodecylammonium chloride in the adsorbed film and micelle

The surface tension of the aqueous solutions of methanol– dodecylammonium chloride (DAC) and ethanol–DAC mixtures has been measured as a function of the total molality of the mixture m^ and the mole fraction of DAC X^2 in the mixture at 298.15 K under atmospheric pressure. The compositions of the adsorbed film at 50, 40, and 30 mN m-1, and that of the micelle at the critical micelle concentration (CMC) have been evaluated by applying the thermodynamic equations derived previously and shown in the form of phase diagrams of adsorption and micelle formation. It has been found that (i) methanol is hardly miscible in M28.8nthe adsorbed film and micelle, and (ii) ethanol molecules are very slightly incorporated into adsorbed film of DAC at high-surface tension and into the micelle, although hardly miscible in the adsorbed film at low-surface tension. By comparing the corresponding phase diagrams of ethanol-2- (octylsulfinyl)ethanol (OSE) mixture, furthermore, it has been shown that there exists a difference in the miscibility of ethanol between DAC and OSE.

Rotator Phase in Dodecylammonium Chloride Studied by 1H and 2H Solid NMR and Thermal Measurements

Abstract 1H NMR spin-lattice relaxation times, T1 and T1ρ, the second moment M2 of 1H NMR linewidth, 2H NMR spectra, powder X-ray diffraction, electrical conductivity, and thermal measurements have been performed on C12H25NH3Cl and C12H25ND3Cl in the range between room temperature and the melting point. From these measurements, the presence of the rotator phase was revealed above ca. 345 K, where a highly disordered structure characterized by the rapid 2-D self-diffusion as well as the axial rotation of the cations taking place in the lamellar-type double layer structure is formed. These molecular motions, the crystal structure and the thermal nature found in this phase indicate that the rotator phase is close to the plastic crystal and can be described as “a low-dimensional plastic phase”. The determined dynamic parameters of molecular motions in this phase were compared with those in the values reported in the rotator phases of short alkyl chain analogues.

Dielectric study of sodium dodecyl sulphate (SDS) adsorption onto galena. Comparison with sodium amyl xanthate and dodecyl ammonium chloride

The strong decrease of the permittivity of powdered galena with the addition of sodium dodecyl sulphate (SDS) can be linked, as in the case of sodium amyl xanthate, to the chemical nature of its bond with the galena surface: physical adsorption of dodecyl ammonium chloride has no dielectric effect in the range 0.4–100 MHz. Voltammetry and electrokinetic measurements show that the adsorption is independent of potential, contrary to the case of xanthate, and results from an exchange between SDS and anionic species onto the surface. X-ray photoelectron (XPS) and diffuse reflectance by infrared Fourier transform (DRIFT) spectroscopies have been investigated to identify the species responsible for the collection mechanism.

Nonideal Mixing in Adsorbed Film and Micelle of Ionic–Nonionic Surfactant Mixtures

The surface tension of aqueous solutions of dodecylammonium chloride–octyl methyl sulfoxide (OMS) and dodecyltrimethylammonium bromide–OMS mixtures was measured as a function of the total molality of surfactants and the composition of OMS. The results were analyzed according to our thermodynamic procedure; the phase diagrams of adsorption and micelle formation and the diagram illustrating the composition relation between the micelle and the adsorbed film at the critical micelle concentration were drawn. The activity coefficient and excess Gibbs energy in the adsorbed film and the micelle were defined and then evaluated from the phase diagrams. They were found to give useful information on the deviation from ideal mixing and intermolecular interaction in the adsorbed film and micelle.

Untersuchungen zum Verhalten von Dodecylammoniumchlorid ın Gegenwart von Additiven / Studies on dodecyl ammonium chloride in the presence of additives

The micellar behaviour of the cationic surfactant dodecyl ammonium chloride (DAC) was determined in different concentrations of methanol, propanol-1, butanol-1, butanol-2, t-butanol in water as well as in pure water at 30°C and also in 0.5 M alkanol + water systems within the range of 30 to 45°C by conductivity and surface tension measurements. Various thermodynamic parameters could be evaluated.

Dependence of Alkyl Chain Conformation of Simple Ionic Surfactants on Head Group Functionality As Studied by Vibrational Sum-Frequency Spectroscopy

The conformational order of sodium dodecyl sulfate (SDS), sodium dodecylsulfonate (DDS), dodecyltrimethylammonium chloride (DTAC), and dodecylammonium chloride (DAC) adsorbed at the D2O/CCl4 interface has been examined by total internal reflection sum-frequency vibrational spectroscopy (VSFS). The vibrational sum-frequency spectra indicate the presence of gauche conformations in the hydrocarbon chains of SDS, DDS, DTAC, and DAC at all surface coverages examined. An increase in the surface concentration of surfactant at the D2O/CCl4 interface results in the reduction of gauche defects in the hydrocarbon chain as determined from the intensity ratio of the methyl to methylene symmetric stretch vibrational modes. Analysis of the SF vibrational spectra suggest significantly different alkyl chain conformations for the cationic and anionic surfactants examined. The alkyl chains of the cationic surfactants DTAC and DAC possess the fewest gauche defects, while SDS and DDS display more disorder in the hydrocarbon c...

Interactions in a binary mixture of cationic surfactants

The properties of the aqueous binary cationic surfactant mixture of dodecylammonium chloride and tetradecylammonium chloride were studied. The adsorption of surfactant chains at the air-solution interface and their association in bulk solution were in vestigated by surface tension and conductivity measurements. The composition of mixed films and mixed micelles, the corresponding activity coefficients of surfactants and the interactions between adsorbed and micellized molecules were determined using the regular solution theory. The investigated surfactants were found to mix slightly non-ideally both in the mixed film and in the mixed micelles.

Volumeneigenschaften der Mischungen von N-Alkylammoniumchloriden und Na-Dodecylsulfat / The volumetric properties of mixtures of N-alkylammonium chlorides and sodium dodecyl sulphate

The densities of octyl, dodecyl and hexadecyl ammonium chlorides sodium dodecyl sulphate and aqueous solutions of these surfactants and their mixtures were determined. From the results obtained, the apparent molar and molecular volumes were determined and compared to those calculated theoretically on the basis of the length and width of the surfactant molecule and the apparent intermolecular distance. Good agreement was found between the molecular volume of the surfactants in the solid state determined from density and calculated theoretically. By comparison of the theoretical and experimental molecular volume of the surfactants, the influence of the octyl and hexadecyl ammonium chlorides and sodium dodecyl sulphate on the c.m.c. of dodecyl ammonium chloride was deduced. It was found that the presence of octyl ammonium chloride in an aqueous solution of dodecyl ammonium chloride increases its c.m.c., but the presence of hexadecyl ammonium chloride and sodium dodecyl sulphate decreases it.

Kinetic study of the protolysis of benzoic acid derivatives in a micelle of dodecylammonium chloride

T. Isoda, M. Yamasaki, H. Yano and S. Harada, J. Chem. Soc., Faraday Trans., 1997, 93, 449 DOI: 10.1039/A605621K

Flotation properties of silicon carbide: I. Flotation of silicon carbide with anionic and cationic collector

This article deals with the results of investigations on the flotation of silicon carbide by means of anionic and cationic collectors. On the basis of a wide range of physico-chemical and flotation tests, a mechanism explaining the effect of these reagents on the flotation of silicon carbide has been suggested. The deficient flotation of SiC in the presence of anionic reagents may be related to the negative charge occurring at the surface of silicon carbide in a wide region of pH (2.7–14), as has been proved by measurements of the electrokinetic potential. It was observed that in the presence of an anionic collector the negative charge increased at the surface of silicon carbide. This may be related to the adsorption of the anionic collector influenced by intermolecular forces between the hydrocarbon chain of the collector and the carbon atoms in the lattice of SiC. Silicon carbide easily flotates by means of cationic collectors. The maximum flotation, when dodecylammonium chloride is being used as collector, occurs at pH = 9. Concentration of amine necessary for obtaining complete flotation recovery of SiC is two orders lower than in the case of quartz. The mechanism of amine action in the flotation of SiC consist in the adsorption of amine as a result of its electrostatic interaction with the negatively charged SiC surface. The negative charge of the surface originates from the silanol groups which are the oxidation product of SiC.

Temperature dependence of the density of an ionic micellar system near the critical point

The density of the system dodecylammonium chloride + water + KCl has been studied as a function of temperature and surfactant composition for two different concentrations of KCl. The data of the critical samples can be described using scaling laws and the 3D Ising value for the critical exponent α. The range of validity of simple scaling for the density is found to be larger than for the order parameter. When combined with previously reported data, the present results confirm the validity of the two-scale factor universality hypothesis in this ionic micellar system. The results obtained for off-critical compositions have been found to be compatible with predictions of the so-called linear model.

Double-exponential relaxation near the critical point of an ionic micellar system.

The system dodecylammonium chloride+water+KCl (0.30M) has been studied using dynamic light scattering near the liquid-liquid critical point. The correlation functions have been found to be single-exponential for temperatures well above the critical one, while a new decay process at longer times becomes evident at |T-${\mathit{T}}_{\mathit{c}}$|4 K. The correlation functions can be well fitted either with the sum of two exponentials or with a double-exponential distribution using Laplace inversion methods. The decay rate associated with the fast relaxation mode has a diffusive character over the whole temperature range, while the decay rate of the slow mode is diffusive in the long-wavelength limit; and at higher wave vectors q shows a crossover from a ${\mathit{q}}^{2}$ to a ${\mathit{q}}^{3}$ dependence. The relative weight of the amplitude of the slow relaxation mode decreases as the temperature and the angle of observation increase. The diffusion coefficient associated with concentration fluctuations has been calculated from both relaxation modes using the characteristics of the matrix equation that relates the transport coefficient matrix and the susceptibility matrix for asymmetric binary fluids. It has been analyzed in terms of the predictions of the mode-coupling theory, and good agreement is found when experimental shear viscosity data are used together with correlation lengths obtained from static light-scattering measurements. The apparent relaxation rate associated with the background contribution has a clear diffusive character, i.e., ${\mathit{q}}^{2}$ dependence. It shows a smooth temperature change and far from ${\mathit{T}}_{\mathit{c}}$ it agrees with the values expected for the micellar dynamic. \textcopyright{} 1996 The American Physical Society.

Chelating modifiers in the cationic silica flotation of magnetic taconite concentrates

Two aromatic-type chelating agents, 1, 10 phenanthroline (phen) and 8-quinolinol (quin), were tested as specific depressants for magnetite in the cationic silica flotation of magnetic taconite concentrates. Micro and batch flotation tests, along with zeta potential and adsorption measurements, were used. In the presence of a cationic collector, dodecylammonium chloride (DAC), the Fe/phen surface chelate electrostatically repelled DAC, and the magnetite was depressed. The negatively charged Fe(quin)2(OH)2− on the magnetite surface attracted the cationic collector and made magnetite floatable.

Long-Range Hydrophobic Forces between Mica Surfaces in Dodecylammonium Chloride Solutions in the Presence of Dodecanol

Hydrophobic forces were measured using a Mark IV surface force apparatus with mica surfaces in equilibrium with dodecylamine hydrochloride (DAHCl) solutions at pH 5.7. With DAHCl alone, only “short-range” hydrophobic forces were observed with decay lengths of 1.3 nm. In the presence of dodecanol, long-range hydrophobic forces were observed with the decay length as large as 9.0 nm, which represents the strongest ever recorded hydrophobic force with soluble single-chain surfactants. The appearance of the long-range hydrophobic forces in the presence of neutral surfactants can be attributed to thecoadsorptionmechanism, by which a close-packed mixed monolayer of dodecylammonium ions and dodecanol is formed on the mica surface. The decay lengths of the hydrophobic forces obtained in the present work and reported in the literature have been plotted vs advancing water contact angles (θa). The results show that long-range hydrophobic forces appear at θa≥ 90°, which may be attributed to the formation of domains of close-packed hydrocarbon chains. These domains may have large dipole moments (or charges), which correlate with those of the opposing surface to give rise to long-range hydrophobic forces. The domains may also serve as sites for microscopic cavitation, as the local contact angle may exceed 90° and thereby satisfy the thermodynamic requirement for cavitation.

Long-Range Hydrophobic Forces between Mica Surfaces in Alkaline Dodecylammonium Chloride Solutions

A Mark IV surface force apparatus was used to measure forces between mica surfaces in dodecylamine hydrochloride (DAHCl) solutions. At pH 5.7, only “short-range” hydrophobic forces with decay lengths of approximately 1.3 nm were observed. At pH 9.5, however, a long-range hydrophobic force with a decay length of 5.5 nm was observed due to the coadsorption of dodecylammonium ions and dodecylamine, which increases the packing density of hydrocarbon chains on the mica surface. At pH 10.1, no significant hydrophobic forces are observed above 2 × 10−5MDAHCl possibly due to the formation of phase-separated amine on the surface. This concentration is 50 times below that of bulk precipitation. Furthermore, the force curves obtained at pH 10.1 exhibit repulsive steric forces at separation distances below 30 nm, which may provide an evidence for the existence of preprecipitation complexes on the surface. The pH at which the long-range hydrophobic force appears corresponds to the pH where the flotation of quartz reaches a maximum, suggesting that long-range hydrophobic forces may be required for good flotation.

Reduction of Potassium Fixation by Two Humic Acid Fractions in Vermiculitic Soils

AbstractThe capacity of soil organic matter (SOM) to reduce K fixation was investigated in calcareous vermiculitic soils. Humic acid fractions were extracted with the use of a modification of the standard NaOH extraction procedure. The mobile humic acid pool (MHA) was extracted without initial decalcification. Addition of MHA to the vermiculitic soils reduced K fixation and resulted in greater total extractable K and highly labile K, as well as greater plant K uptake. The Ca humate pool (CaHA) was extracted after decalcification, and it had little effect on K availability. An increase in extractable and highly labile K occurred within 4 h of MHA addition and thus appears to result from a rapid exchange reaction and not from mineral dissolution; the latter was confirmed in separate experiments with organic acids. This rapid effect could be reproduced by addition of dodecylammonium chloride. We speculate that the enriched amino acid content and increased solubility of MHA, compared with the more humified CaHA, contribute to the greater influence of MHA on K equilibria. The less soluble, more condensed CaHA is more likely to precipitate with Ca2+. The capacity of solubilized MHA to hold K+ against soil adsorption was also apparent when soil was separated from MHA by a dialysis membrane. These results provide further evidence that young N‐rich SOM fractions such as MHA play an important role in governing K availability in soils with high K fixation potential.

Micellar Catalytic Effects on the Kinetics of the Ionization of Basic Amino Acid and Acidic Amino Acid Studied by the Ultrasonic Absorption Method

Base equilibria of arginine (basic amino acid) in the absence of a micelle and then in a micellar solution of sodium dodecyl sulfate (SDS) have been studied by ultrasonic absorption measurements. Forward (γ 2 k f ) and backward (k b ) rate constants, the apparent base dissociation constant K b (=k b /γ 2 k f ), and the volume change (ΔV) for the reaction were obtained. Micellar effects for arginine were greater than those for a neutral amino acid measured previously. This is discussed in terms of total charge of the amino acids. Similar experiments were carried out for aspartic acid (acidic amino acid)-cationic micelle of dodecyl-ammonium chloride (DAC). Relaxation was considered due to the protolysis of aspartic acid. A slightly lower micellar effect than that for an aromatic carboxylic acid-dodecylammonium chloride (DAC) system was noted. ΔV was smaller than that for an aromatic carboxylic acid with the same pK a