Hexadecyltrimethylammonium Ion Research Articles

Study of permanently coated columns for the high-performance liquid chromatographic determination of sulphur anions in environmental samples from metallurgical processes

The behaviour of styrene—divinylbenzene and bonded C 18 reversed-phases permanently coated with cetylpyridinium ion or hexadecyltrimethylammonium ion (“permanent coating” ion-interaction chromatography) were investigated for the determination of sulphur species in samples from studies on enviromnental control in metallurgical processes. The advantages of these types of exchanger are the ability to vary the ion-exchange capacity and the attainment of high column efficiency. Also demonstrated is the effect of an organic modifier on the control of retention and the wide linear range calibration curves ofbtained with these columns. Examples of application to the analysis of effluents and acid-tailings residues from metallurgical processing operations for the determination of sulphate, thiosulphate and thiocyanate anions are given. Detection was by indirect UV absorption.

Micellar Effects upon Spontaneous and Alkaline Hydrolysis of t-Butyl Phenyl Carbonate

Abstract Cationic micelles of hexadecyltrimethylammonium ion HTAX (X=Cl− and OH−) catalyzes the reactions of t-butyl phenyl carbonate with OH− and kΨ goes through maximum with increasing [HTACl] but it continues to increase with increasing [HTAOH]. Spontaneous hydrolysis of t-butyl phenyl carbonate is inhibited by both cationic and anionic micelles. The second-order rate constant in micelles is smaller than that in water.

In situ determination of calcium carboxymethylcellulose on a cellulose film via ion exchange

AbstractA simple and rapid ion exchange method is presented for the in situ determination of calcium carboxymethylcellulose (CaCMC) on a cellulose film. The method is based on the ion‐exchange reaction between the calcium ion in CMC and a large quaternary ammonium ion, such as hexadecyltrimethylammonium ion, followed by a second ion exchange reaction in which the quaternary ammonium ion is displaced by 3,9‐bisdimethylaminophenazothionium ion. The development of a blue color allows for the determination of the CaCMC distribution on the film by using a scanning densitometer. The reasons that CMC prefers a relatively large quaternary ammonium ion to the divalent calcium ion are suggested. This method is also applicable for the determination of sodium carboxymethylcellulose film where it is only necessary to carry out the second ion‐exchange reaction. The minimum detection limit for a CaCMC (degree of substitution is 0.7) coating is at least 1 μg/cm2.

Effect of Counterionic Species on the Adsorption of Tetradecyltrimethylammonium Ion at the Polarized Nitrobenzene–Water Interface

Abstract The effect of counterions, F−, Cl−, and Br− on the adsorption of the hexadecyltrimethylammonium ion (HTMA+) at the polarized nitrobenzene–water interface has been studied by measuring electrocapillary curves. The interfacial tension in the negative branch of the electrocapillary curve, where the interface is polarized such that the potential in the aqueous phase is negative with respect to that in the nitrobenzene phase, was lowered due to the specific adsorption of HTMA+ ion at the interface. The magnitude of interfacial tension depression in the negative branch became larger in the order F−, Cl−, and Br−, indicating a specific counterion binding at the interface in this order. The adsorption free energy of the HTMA+ ion, ΔGa0, for the adsorption of HTMA+ ion at the interface from the nitrobenzene phase was found to depend markedly on the anionic species present in the aqueous side of the interface. This ΔGa0 values can be taken as a quantitative measure of the counterion specificity at the interface. The meaning of the fact that the change in the shape of the electrocapillary curves depends on the counterion species is discussed in detail in terms of the thermodynamics of the oil–water interface.

The Effect of the Electrical Potential Difference on the Adsorption of the Hexadecyltrimethylammonium Ion at the Polarized Nitrobenzene–Water Interface

Abstract The adsorption of the hexadecyltrimethylammonium ion(HTMA+) at the polarized nitrobenzene–water interface has been studied using electrocapillary measurements. The adsorption of HTMA+ was found to be markedly dependent on the potential drop across the interface. HTMA+ exhibited no specific adsorption in the potential range where the aqueous phase is positive, whereas a strong adsorption occurred in the potential range where the electric potential in the aqueous phase is negative with respect to that in the nitrobenzene. The adsorption free energy depends linearly on the potential difference across the interface. The specific adsorption of HTMA+ significantly alters the double-layer structure. The outer Helmholtz potential in the nitrobenzene phase was inverted from negative to positive due to the adsorption of HTMA+ ions.

Quantitative determination of alkylammonium amphiphiles using neutral detergents

Orange G forms stable complexes with dioctadecyldimethylammonium and hexadecyltrimethylammonium ions which can be solubilized in aqueous solutions containing Brij 35. The changes in absorbance, due to complex formation in the presence of Brij 35, were used to develop a fast, reproducible, and sensitive method for the quantitative analysis of long-chain alkylammonium amphiphiles.