Du Nouy Ring Method Research Articles

The behaviour of surfactants in concentrated acids 5. Micellization and interfacial activity of n-alkyltrimethylammonium bromides in methane sulphonic acid and concentrated sulphuric acid

The adsorption isotherms of n-alkyltrimethylammonium bromides for the interfaces CH 3SO 3H/ n-hexane and conc.H 2SO 4/ n-hexane were determined by du Nouy's ring method. The measurement data were evaluated by approximation to the Von Szyskowski equation. The standard deviation was <3.5%. The CMC values of the homologous series were determined. They show a good correlation with the Klevens equation. The change in the energy of micelle formation —Δ M G and the energy of adsorption —Δ- G 0 as a function of the chain length was calculated as well as the plot of surface concentration against surfactant concentration, the maximum surface coverage and the percentage surface concentration at the CMC. The results obtained in the different solvents are compared with each other and also with the results at the conc.H 2SO 4/air interface obtained earlier. The chemical surfactant properties of n-C n H 2 n+1 N(CH 3) + 3 Br − are still less pronounced in methane sulphonic acid than in concentrated sulphuric acid. The surface tension decreases less strongly. The CMC values were found only for the C 14−, C 16− and C 18−homologues and occur at much higher concentrations. The energies of micelle formation and of adsorption are considerably less. The results obtained on the conc.H 2SO 4/ n-hexane interface differ considerably from those for conc.H 2SO 4/air. The adsorption tendency clearly predominates in the former.

Importance of bulk and surface excess concentration in fast atom bombardment mass spectrometry of small peptides

The surface tension of hydrophilic and hydrophobic peptides in glycerol solution at various concentrations is measured by the du Nouy ring method. From these values the surface excess concentration is calculated by means of the Gibbs adsorption equation. The behaviour of the surface excess peptide concentration on the fast atom bombardment mass spectrometric response (protonated molecular ion) as a function of the bulk peptide concentration in glycerol is discussed in terms of parameters commonly used in surface chemistry. The experimental results showed a straightforward correlation between the sputtering of protonated molecular ions of peptides and surface excess peptide concentration. Further, there is good agreement with a model involving desorption/ionization in the first layers of the liquid matrix surface. It is additionally demonstrated that the surface excess concentration of each peptide will be different in glycerol solutions of identical bulk concentration and, as a consequence, any differences in protonated molecular ion yield will reflect differences in the surface activity of the peptides, which explains suppression phenomena in peptide mixtures such as tryptic peptide digest. Based on this finding, it can be assumed that a difference observed in the mass spectrometric response does not represent a substantial difference in ionization efficiency.

The Effect of Mutual Solvents on Adsorption In Sandstone Acidizing

The role of mutual solvents in sandstone acidizing is investigated. An experimental technique for evaluating various solvents was used to examine various classes of solvents to relate chemical structure to mutual solvent properties. Glycol ethers were the most effective class of chemicals examined. Introduction Acid solutions containing hydrofluoric acid have been used extensively to stimulate sandstone reservoirs. Normally, these solutions are restricted to treating shallow clay damage due to the extremely fast spending rate of HF on clay. In acidizing sandstone formations, the acid is pumped below fracturing pressure, and the large surface area of the formation matrix is contacted and reacted upon by the acid. Stimulation fluids usually contain various surfactant additives in an effort to help control emulsions, asphaltenic sludge deposits, surface tension, and corrosion of steel. When acid solutions containing surfactants contact the rock surface, significant amounts of additives can be adsorbed onto the rock. These adsorbed additives are then no longer present in the fluids to perform their designed function. Consequently, conditions the surfactants were supposed to help control may occur during or after the treatment, resulting in less-than-satisfactory stimulation results. In 1971, Gidley reported on the use of the mutual solvent ethylene glycol monobutyl ether (EGMBE) in conjunction with sandstone acidizing treatments. Significant improvements were observed when the mutual solvent was present in either the acid solution or the oil after-flush. Gidley also pointed out the importance of proper treating technique. The mutual solvent was proper treating technique. The mutual solvent was shown to decrease the stability of acid/oil emulsions in the presence of formation fines. The compatibility of some acid additives with formation fluids and mineral surfaces was investigated by Sutton and Lasater. Their findings supported those of Gidley that EGMBE does improve the separation of acid solution/crude oil emulsions. Sutton and Lasater attributed this to decreased adsorption of surfactant on silica surfaces in the presence of EGMBE. They also found that acid corrosion inhibitors exhibited reduced adsorption on silica when EGMBE was present in the acid. The present investigation included two phases of work:a study of various classes of solvents to relate chemical structure to mutual solvent properties, anda further study of the influence of mutual solvents on surfactant adsorption. Experimental Procedure Adsorption effects were observed by measuring solution properties before and after flowing acid solutions properties before and after flowing acid solutions through columns packed with either silica sand or a mixture of silica sand and clay. The procedure for preparing the columns and performing the flow tests is preparing the columns and performing the flow tests is outlined in the Appendix. Solution properties measured were surface tension, emulsification, and corrosiveness. Surface tensions, reported in dynes per centimeter, were measured using the du Nouy ring method. Emulsion tests were conducted by mixing equal volumes of acid solutions and a crude oil from Southern Louisiana at 15,000 rpm for 1 minute with an Eberbach stirrer equipped with an homogenizer head. Separation of acid and oil was noted after 10 minutes and was reported as percent acid separated. JPT P. 1439

An Improved Apparatus for Interfacial Tension Measurement by the Ring Method

An apparatus for measuring both the interfacial tension by the DuNouy ring method and the film elongation is described which uses a stepmotor to raise or lower the interface past the ring.

Adsorption of toluene‐soluble polymers at the toluene–water interface

AbstractThe adsorption of several toluene‐soluble polymers at the toluene–water interface has been investigated by using the duNouy ring method of measuring interfacial tension γT/W. Polystyrene and poly(ethylene‐co‐vinyl acetate) (11.1 mole‐% vinyl acetate) have little affinity for this interface at 29°C, but poly(methyl methacrylate) (PMMA) (M̄n = 420,000) and ethyl cellulose (EC) (M̄n = 50,100; 49.1% ethoxyl) adsorb significantly at concentrations as low as 1.0 × 10−4 g/100ml. A plot of interfacial tension lowering versus initial logarithm of initial bulk phase polymer concentration is linear from 1.0 × 10−4 to 1.0 × 10−1 g/100 ml for EC and 1.0 × 10−4 to 1.0 × 10−2 g/100 ml for PMMA. When the PMMA concentration increases to 1.15 × 10−1 g/100 ml, its adsorption behavior changes markedly. Prolonged time effects occur and adsorption becomes dependent upon dissolved water content of the toluene prior to formation of the toluene/water interface. Such effects are not observed with the other solutions studied. Increasing temperatures have variable effects on values of γT/W for the polymer solutions studied. Experiments with various polymer mixtures indicate that the polymer lowering T/W the most is preferentially adsorbed at the toluene–water interface and rapidly displaces less strongly adsorbed polymers.

Sur les Erreurs Causées par L'Évaporation dans les Mesures de Tension Superficielle

AbstractEvaporation of solute in aqueous solutions of long chain alcohols and acids may cause important errors in measures of the surface tensions of these solutions.The work described in the present paper has shown that, even in a closed vessel, the vapour pressure of the solute is not uniform and particularly with the pendant drop method, the heavy vapours do not remain near the drop, where the surface tension is measured.The du Nouy ring method and the pendant drop method have been improved to avoid evaporation.Various anomalies, found in the literature, have been shown to be due to evaporation, especially the «bag» effect found by Addison with decyl alcohol solutions, and the minimum in the time curves of surface tension observed by Ward and Ottman with capric acid solutions.

Cyclohexylchlororesorcinol のガマ線虫 (Spinicauda japoinca &lt;I&gt;Wilkie&lt;/I&gt;) 殺滅効力に及ぼす界面活性剤の影響

Several kinds of surface active agents-i.e., cationic : cetylmethyl diethyl ammonium methosulfate, cetylmethyl piperidinium methosulfate, non-ionic : Tween 20, Tween 60, and Span 20, anionic : dioctyl ester sodium sulfosuccinic acid, sodium oleate-were added according to the various steps of concentration to 0.01% solution of 4-n-cyclo-hexyl-6-chlororesorcinol (C. H. C. R.) in phosphate buffered, pH 7.5, frog-Ringers' solution. Then, the mortality percent of Spinicauda japonica Wilkie, a nematoda species inhabiting toad's large intestine, after immersed in these solutions for certain minutes, was observed by modified Lamson's method, and parallel measurement was carried out their interfacial tension against liquid-parrafin by Hillyer's drop method and du Nouy's ring method. The results obtained were : the soaps in dilute solution increased remarkably the biological activity of C. H. C. R. (as measured by the mortality percent) but when present in high 'concentration it decreased the activity. In these cases, the least concentration of soap to increase the biological activity of these solutions corresponded to the concentration at which the interfacial tenision bgins to fall, when measured by drop method, but not by ring method, but the maximum acceleration ot the activity occurred at the concentration where the interfacial tension by ring method indicated minimum. However, in the case of Tween, such acceleration of the biological activity of the solution was not observed throughout its concentrations, and the more concentrated the more markedly decreased. These results were discussed from the sufacechemical point of view.