Ying-Chech Chiu

USING ELECTROPHORESIS TO DETERMINE ZETA POTENTIAL OF MICELLES AND CRITICAL MICELLE CONCENTRATION

Abstract A heterodyne laser Doppler electrophoresis method for measuring the zeta potential of a surfactant micelle has been developed. Details of the method and results obtained will be presented in this paper. In comparison with the tracer electrophoresis method used in determining the zeta potential of a surfactant micelle, this method is much time saving and less laborious. The zeta potential values of one anionic and three cationic surfactant micelles have been determined by using this method. From the zeta potential versus concentration curve, one can determine the micellar dissociation concentration and the critical mi cellar concentration of a surfactant. The values obtained agree quite well with the surface tension measurement. The surfactant systems were studied in the presence and absence of NaCI. The zeta potential appears to decrease with the increase of NaCI concentration.

SIMULTANEOUS DETERMINATION OF MICELLAR DISSOCIATION CONCENTRATION AND CRITICAL MICELLAR CONCENTRATION OF BILE SALTS BY pH MEASUREMENTS

ABSTRACT This paper demonstrates a method of using a pH meter to determine the micellar dissociation concentration (mdc) and the. critical micellar concentration (cmc) of eight bile salt samples: sodium cholate (NaC), sodium deoxycholate (NaDC), sodium glycocholate (NaGC), sodium glycodeoxycholate (NaGDC), sodium glyco-chenodeoxycholate (NaGCDC), sodium taurocholate (NaTC), sodium taurodeoxycholate (NaTDC) and sodium taurochenodeoxycholate (NaTCDC). The experiments were performed by diluting the bile salt solutions with freshly distilled water and following the pH changes with a hydrogen ion electrode at 25°C. One break appears in most of the pH-concentration plots of the bile salt solutions, signifying mdc. However, two breaks appear for NaC and NaDC samples, signifying mdc and cmc. The mdc and cmc values are in good agreement with values determined by surface tension and turbidity methods and with data reported in the literature. The method described in this paper is quick, simple and requiring no sampl...

DETERMINATION OF LONG-TERM STABILITY OF VITAMIN E EMULSION AND FORMATION OF MICROEMULSIONS BY USING LASER LIGHT SCATTERING AND UV ABSORPTION MEASUREMENTS

Abstract This paper presents methods of determining the long-term stability of vitamin E emulsion and formation of microemulsions. Several emulsion systems formed by using anionic, zwitterionic and cationic surfactants have been studied in the presence and absence of NaCI. Several conclusions can be drawn: (1) by using UV absorption and particle size measurements, one may be able to predict the long-term stability of an emulsion or the possibility of forming a microemulsion by measuring the initial properties of an emulsion, (2) in order to form a stable vitamin E emulsion or microemulsion, the initial properties of the emulsion should have the following features : (a) the particle size is ≤ 200 nm, (b) the surfactant system has a saturation value ≥ 1 and (c) the surfactant system can dissolve a substantial amount of vitamin E without causing an increase of the emulsion droplet size and (3) the saturation value and the stability of many vitamin E emulsion systems can be increased by adding an optimum amou...

Application of pH measurement to determine the micellar properties of mixed bile salt and nonionic surfactant systems

ABSTRACT This paper applies pH measurement to determine the micellar dissociation concentration (mdc) and the critical micellar concentration (cmc) of mixed sodium cholate (or sodium deoxy-cholate) and octaethylene glycol mono n-decylether nonionic surfactant systems. The experiments were performed by diluting the mixed surfactant solutions with freshly distilled water and following the pH changes with a hydrogen ion electrode at 25°C. Two breaks appear in the pH-concentration plots of the mixed surfactant systems, signifying mdc and cmc. The cmc values for the mixed micelles are in good agreement with values reported in the literature. One may also estimate the cmc of the pure component from data obtained for the mixture without going through the trouble of sample purification. The method of using pH measurement to determine mdc and cmc is quick and simple. It requires little training.

INTERFACIAL TENSION AND FORMULATION PRINCIPLE OF ULTRALOW INTERFAC1AL TENSION SYSTEMS FORMULATED WITH CARBOXYMETHYL ETHOXYLATES UNDER EXTREMELY HIGH CALCIUM ION CONCENTRATION

ABSTRACT This paper will present some data of ultralow interfacial tension obtained in carboxymethylated ethoxylate-crude oil systems under extremely high calcium ion concentrations (0.5-1,5 M). A commercial surfactant, Huls B433 is used in the formulation of the surfactant systems. Dynamic interfacial tension (IFT) was measured with a spinning drop apparatus at 25 C. The measurements were performed by varying the surfactant and CaCl2-concentrations in the formulation. An IFT minimum (∼10 dyne/cm) was found at 0.01 wt% surfactant concentration and 1.0 M CaCl2 concentration. Laser light scattering technique was applied to study the micellar size in the surfactant solutions. Large surfactant micelles around 100 nm seemed to be present in the surfactant solutions containing the optimum electrolyte concentration. Tentative correlation between IFT and surfactant micellar size will be given. It is suggested that the micellar size, a measurable and controllable factor, can be used as a guidance for surfactant fo...

Vitamin E dissolution in sulfobetaine zwitterionic surfactant solution and enhancement of dissolution by adding sodium chloride

Vitamin E is widely used in pharmaceutical, food and cosmetic preparations. This paper discusses methods of preparing vitamin E emulsions by using sulfobetaine (SB) zwitterionic surfactants which have high electrolyte tolerance. The amount of vitamin E dissolved in water was analyzed by turbidity and UV absorption measurements. The emulsion droplet size was determined by laser light scattering. Microemulsions with small particle size and high resistance to oxidation in air can be obtained by solubilizing vitamin E in SB solutions at high concentrations (above 1%). The performance of a series of SB surfactants is compared in 1.5% solutions. A SB surfactant with a 12 carbon chain seems to be the most effective in dissolving vitamin E. The saturation value of vitamin E is increased about one order of magnitude by adding NaCI to the SB surfactant solutions. Emulsions formed in surfactant solutions containing NaCI (0.4-0.6 M) are stable at low surfactant concentrations such as 0.2-0.4 %. The emulsion droplet sizes are below or around 200nm.

The Possibility of Using Disulfonated Cosurfactant for Enhanced Oil Recovery

This paper will present a view on the use of a disulfonated surfactant to increase electrolyte tolerance of petroleum sulfonate at medium temperature. A series of thermally stable and commercially available disulfonate, Dowfax, was used with petroleum sulfonate for enhanced oil recovery. Laboratory experiments were carried out with the Dowfax-petroleum sulfonate systems at temperature around 70–75°C under different conditions. Good oil recovery was obtained in Berea sandstone cores with short slug injection against highly saline synthetic field water. Sulfonate loss is around 0.05 meq/100 g rock which is typical for Berea Sandstone. For reservoir application, more experiments are required.

THE USE OF CARBOXYMETHYL ETHOXYLATE SURFACTANT TO DISSOLVE VITAMIN K1 AND TO OBTAIN LOW INTERFACIAL TENSION AND STABLE EMULSION SYSTEMS

Abstract The presence of vitamin K1 in human body is important for preventing the hemorrhagic disease. Due to its very long side chain, vitamin K1 is highly insoluble in water. We have successfully dissolve a substantial amount of vitamin K1 in solutions of a commercial surfactant containing carboxymethyl ethoxylates (Hüls B433) and obtained low interfacial tension (IFT) and stable emulsion systems. This paper will present the details of these experiments. The solubilization of vitamin K1 was estimated from UV absorption. The IFT values were measured by using a spinning drop apparatus and all particle sizes were determined by using laser light scattering. By using the Hüls B433 surfactant and an optimum amount of CaCl2, we can dissolve vitamin K1 in water and obtain low IFT systems in the order of 10−2 dyne/cm. The emulsions obtained in these systems are stable and contain droplet sizes below 65 nm. The dissolution of vitamin K1 and the IFT behavior in these systems follow the rules for crude oil and prefer larger surfactant micelles.

A NEW APPROACH FOR DETERMINING THE REACTION RATIO BETWEEN CALCIUM AND SURFACTANT HAVING LOW CALCIUM TOLERANCE: APPLICATION TO BILE SALT

ABSTRACT Calcium-bile salt interaction plays an important role in gallstone formation and lipid solubilization in human digestive system. This paper presents a method of studying the calcium-bile salt interaction for several bile salts having low electrolyte tolerance. Sodium cholate, sodium glycodeoxycholate, sodium glyco-chenodeoxycholate and sodium deoxycholate were used in this study. Potentiometric titration was performed with calcium ion electrode to determine the calcium-bile salt reaction ratio and the equilibrium constant. Flocculation values by calcium or sodium ions were measured as a function of the bile salt concentration. The flocculation-concentration curves appear to be quite complicated. Precipitation of the bile salt was carefully avoided by adjusting the concentration of the reactants and taking the flocculation-concentration curve as a guidance. For sodium deoxycholate which has extremely low calcium tolerance, the precipitation was postponed by adding nonionic surfactant. Complete tit...