Types Of Cationic Surfactants Research Articles

Separation of Cobalt and Nickel by Liquid Surfactant Membranes Containing a Synthesized Cationic Surfactant

ABSTRACT Separation of cobalt(II) and nickel(II) by using a hydroxyoxime extractant has been investigated both in liquid-liquid extraction and in a liquid surfactant membrane(LSM) system. In the liquid-liquid equilibrium extraction studies, hydroxyoximes showed significant extractability for nickel ions, although LIX 84 was found to have exceptional chelating affinity for nickel ions. In the LSM system functionalized by hydroxyoxime, the cobalt ions were efficiently separated from nickel ions as a result of slower permeation of nickel chelates across the emulsion membrane. More complete cobalt recovery was achieved in the LSMs dosed with LIX 860 than when the same carrier was applied to the liquid-liquid extraction system. Furthermore, cobalt permeation rate was enhanced threefold when a quaternary ammonium type of cationic surfactant was used as an emulsifier due to carrier interaction with surfactant at the reaction interface. The permeation mechanism of ions in LSMs was elucidated by an interfacial reaction model which took into account the adsorption of the carrier and surfactant at the reaction interface.

Adjusting the selectivity of inorganic anion separation by capillary electrophoresis

AbstractThe separation of the principal inorganic anions (bromide, carbonate, chlorate, chloride, fluoride, nitrate, nitrite, sulfate, phosphate) has been achieved using a capillary electrophoresis system with indirect UV detection at 260 nm. Several types of cationic surfactants (quaternary ammonium, phosphonium or methonium) were tested as electroosmotic flow modifiers and added to a chromatebased buffer prepared from potassium dichromate. The influence of many physicochemical parameters such as nature and concentration of cationic surfactant, buffer pH, dichromate concentration buffer, voltage and temperature upon the migration time of an analyte anion, peak efficiency, asymmetry factor, and finally resolution has been investigated. A linear relationship between the corrected area and the anion concentration in the 2.5–50 ppm range was obtained, thus allowing the quantitative analysis of anions in mineral water. Finally, by increasing the hydrodynamic injection time, the separation of inorganic anions at a low concentration level of 50 ng/ml was achieved without any loss of resolution.

Thermodynamic Micellar Properties of n-Octyldimethylamine Oxide Hydrochloride in Water

The apparent molar volumes and heat capacities of n-octyldimethylamine oxide hydrochloride (OAOHCl) were measured in water as a function of concentration between 2 and 55 °C and the apparent molar relative enthalpies of the same system at 25°C. The apparent molar expansibilities were calculated from the temperature dependence of the volumes. The volumes and heat capacities were also measured at 25°C for trimethylamine oxide hydrochloride in water in order to check the group additivity. The data for OAOHCl were fitted with a mass-action model (J. Phys. Chem. 1983, 87, 1397) and compared with those of n-octyldimethylamine oxide (OAO) and n-octylammonium bromide (OABr) in order to investigate the effect of the charge on the thermodynamic micellar properties. A comparison between the properties of OAOHCl and OABr shows that OAOHCl behaves as a typical cationic surfactant. The differences in the thermodynamic properties of micellization between OAO and OAOHCl are as expected from a stronger hydration in the premicellar region and counterion binding beyond the critical micellar concentration (cmc) of OAOHCl. The temperature dependence of most micellar properties is comparable for the two surfactants. As it is generally observed with ionic surfactants, the enthalpy of micellization of OAOHCl is endothermic at low temperature and exothermic at high temperature and the cmc goes through a minimum at about 35°C. However, the cmc of both surfactants at 25 °C are of the same magnitude. From the mass-action model, the thermodynamic properties of the surfactant can be predicted at any temperature and concentration in the range measured.

Effect of pressure on the colloidal solution behavior of aqueous local anesthetic tetracaine solutions

The solution behavior of two local anesthetics, tetracaine hydrochloride (TC·HCl) and tetracaine hydrobromide (TC·HBr), in water was studied. The temperature-pressure diagrams of aqueous TC·HCl and TC·HBr solutions of different concentrations were determined by observing the sudden change in transmittance accompanying the phase transition from the coagel phase to the micellar solution under high pressure up to 170 MPa. The transition temperature was linearly elevated by applying pressure. It was seen that the temperature-pressure slopes of both anesthetics increase with increasing concentration and become constant above 0.3 mol kg −1. We obtained the concentration-temperature phase diagram of TC·HCl solution from the solubility vs. temperature curves at different pressures, which were determined from the concentration dependence of the temperature-pressure diagrams, and the critical micelle concentration (CMC) vs. temperature curves. The solubility curve intersects the CMC curve at a certain temperature under atmospheric pressure, which is regarded as the Krafft temperature of TC·HCl. The volume change associated with the phase transition from coagel to micelle was estimated from the Clapeyron-Clausius equation using the values of the temperature-pressure slope above 0.3 mol kg −1 and the transition enthalpy taken from the DSC study. The values were determined to be 8.4 cm 3 mol −1 for TC·HCl and 9.5 cm 3 mol −1 for TC·HBr, respectively. Further, by considering the volume change of transition for TC·HCl among three states of anesthetic assembly, it was concluded that the solution behavior of these anesthetics in water bears a striking resemblance, with respect to volume, to that of typical cationic surfactants such as alkyltrimethylammonium salts.

Esterquat-A New Cationic Ingredient for Cosmetic Formulations

We introduced a new type of cationic surfactant. The esterquats are safe and interesting raw materials with respect to their toxicity, dermatology, ecology and performance. Their efficacy is equivalent to other quaternary components like DSDMAC or CTAC. With its comparable applicational profile esterquats fit very well into modern concepts for cosmetics and toiletries.

The effect of surface active agents on the microelectrophoretic properties of a polystyrene latex dispersion. Microelectrophoretic studies

The effect of adding anionic (sodium alkyl sulphates), cationic (alkyltrimethylammonium bromides), and nonionic (polyoxyethylene glycol monoethers of n alkanols) surface active agents, and mixtures of these ionic and nonionic species, on the electrophoretic properties of a monodisperse polystyrene latex dispersion has been studied. The nonionic surfactants are probably adsorbed in a looped monolayer as shown by a plateau region in electrophoretic mobility versus concentration plots. With cationic surfactants adsorption is a two-stage process characterized by neutralization of negative charge followed by charge reversal. The free energy of adsorption is dependent on alkyl chain length, the adsorption process being controlled by the hydrophobic effect. Displacement of the reversal of charge concentration by nonionic surfactant depends on its concentration and the type of cationic surfactant. Adsorption of anionic surface active agents causes an increase in zeta potential. An estimate of the free energy of adsorption can be made from the slope of the zeta potential versus log concentration surfactant plot. Added nonionic surface active agents are found to complex with anionics, complexation being dependent on ethylene oxide chain length.