Effect of alkaline materials on interfacial rheological properties of oil-water systems

Interfacial rheological properties of a model crude oil-water system were studied in the presence of sodium hydroxide. The interfacial viscosity, the non-Newtonian flow behavior and the activation energy of viscous flow were determined as a function of shear rate, alkali concentration and aging time. The fundamental conclusion of the experimental results is that the interfacial viscosity drastically decreases in the presence of alkaline materials and the change under favorable conditions may exceed 3 or 4 orders of magnitude. Simultaneously, the sodium hydroxide effectively suppresses the non-Newtonian flow behavior of the interfacial layer. The experimental observations are explained by simultaneous chemical processes taking place in the boundary layer. The present data may help to elucidate the formation, stability and breaking of alkali-containing oil-water emulsions and they provide additional information for better understanding of the displacement mechanism and for the formulation of alkaline flooding as a potential chemically enhanced oil-recovery method. Received: 6 April 1998 Accepted: 18 August 1998     

Experimental Study of the Effect of Strong Alkali on Lowering the Interfacial Tension of Oil/Heavy Alkylbenzene Sulfonates System

Experimental studies were conducted to explore the fundamental mechanisms of alkali to lower the interfacial tension of oil/heavy alkylbenzene sulfonates (HABS) system. Sodium hydroxide was used as the strong alkali chemical to investigate the interfacial tension (IFT) of oil/HABS system. The influences of salt and alkali on the interfacial activity were studied by the measurement of interfacial tension and partition coefficient. Moreover, the alkali/surfactant solutions were measured by dynamic laser scattering. The results showed that compared with the salt, the function of alkali to lower the interfacial tension and improve partition coefficient is more significant. The micelles formed by surfactants could be disaggregated because of adding alkali, so the size of micelles decreases and the number of mono‐surfactants increases, then more surfactant molecules move to the interface of oil/surfactant system and the adsorption of surfactants at oil‐water interfaces increases, which can lead to the decrease of IFT.     

On the reactivity of innercomplex-bonded palladium : A new specific test for cyanides in alkaline solutions

It has been found that the innercomplex salts of palladium with dimethylglyoxime, (benzildioxime and furildioxime), salicylaldoxime and 8-hydroxyquinolinc do not enter into redox reaction with carbon monoxide, cither in solid or in molecular dispersed form.Solutions of palladium-dimethylglyoxime and palladium-salicylaldoxime in alkali hydroxide or ammonia are masked with respect to many reactions of the palladium as well as of the organic components. In alkaline solutions, when adding alkali cyanide, demasking occurs, with the deliberation of the innercomplex forming organic components. For the processes of dissolution and demasking appropriated equations are suggested.The demasking of dimethylglyoximc in alkaline solutions of palladium dimethylglyoxime permits a new sensitive test for cyanide ion. This cyanide test seems to be appropriate for the detection of illuminating gas.Palladium hydroxyquinorate is insoluble in solutions of alkali cyanides, though it is not precipitable from cyanide containing palladium solutions. An explanation for this “false equilibrium” is suggested.     

The Application of Ammonium Hydroxide and Sodium Hydroxide for Reagent Softening of Water

The calcium carbonate crystallization from aqueous solutions in the presence of alkali additives such as sodium hydroxide and ammonium hydroxide has been researched. It is found CaCO₃ crystallizes predominantly in the modification of aragonite in the presence of ammonium hydroxide. The calcium carbonate formation rate in an alkaline medium and the gaseous reaction products due to sorption of gas bubbles on crystal surfaces, affect the aragonite structure formation. It is shown use of ammonium hydroxide for water treatment can solve two urgent tasks such as water softening and exclusion sediment of deposits on the equipment surfaces by a calcium carbonate crystallization in the form of aragonite.     

酸性和碱性介质中甘氨酸解离吸附和氧化的EQCM研究

用电化学石英晶体微天平(EQCM)研究酸性和碱性介质中甘氨酸在Pt电极上的吸附和氧化过程.结果表明,甘氨酸的解离吸附和氧化行为与溶液的酸碱性密切相关.酸性溶液中甘氨酸吸附较弱,碱性溶液中则产生强吸附物,且当电位低于0V(vs.SCE)时可吸附于Pt电极表面.此外,碱性溶液中甘氨酸还表现出较高的电氧化活性.通过EQCM定量检测上述过程中Pt电极表面的质量变化,测定了不同电位区间(氢区、双电层区和氧区)每传递一个电子所对应的电极表面吸附物种的平均摩尔质量.     

Effect of Glycine and Monoethanolamine on the Stability and Reductive Activity of Thiourea Dioxide in Aqueous Solutions

The effect of glycine and monoethanolamine on the stability and reductive activity of thiourea dioxide in the reaction with acid orange II dye was studied. It was found that, in contrast to glycine, introduction of additives of monoethanolamine into aqueous solution of thiourea dioxide substantially increases its reductive activity in alkaline solutions, although the stability of the thiourea dioxide monoethanol amine derivative in alkaline solutions is much lower than that of thiourea dioxide and the product of its reaction with glycine.     

Potentiometric studies of dithiooxamide with a sulphide-selective membrane electrode

The sulphide-selective electrode is applicable to the determination of dithiooxamide by titration with silver nitrate. The effect of the alkali content of the solutions on the reaction has been studied. The reaction products are silver sulphide, oxalic acid, and nitric acid. If the alkali concentration of the solution is lower than that equivalent to the acid formed during the titration, the amount of sulphide produced by hydrolysis decreases and the equilibrium potential is established more slowly.The determination is rapid and accurate in the presence of 1 M sodium hydroxide.     

Biosorption of Heavy Metal Ions to A Marine Microalga, Heterosigma akashiwo (Hada) Hada

Alkaline flooding is a method of enhanced oil recovery that relies on the formation of surface-active substances in situ by a chemical reaction between acidic components in the oil and an alkaline reagent. As the injected alkali advances through the porous medium, it keeps contacting fresh oil. At some moment dependent on the alkali/acid concentrations and the velocity, the alkali at the advancing front may become depleted and the flood becomes interfacially nonreactive. The present study is aimed at investigating the above-mentioned phenomena. Displacement studies were conducted in radial cells containing sintered glass beads as a porous medium. Light paraffin oil acidified with 10 mmol/L of linoleic acid served as the displaced (oil) phase while the displacing aqueous solution contained 0-25 mmol/L of sodium hydroxide. The highest oil recovery was obtained under the conditions of low flow rate and high alkali concentration. Increasing the flow rate at high NaOH concentration resulted in decreasing oil recovery up to a certain threshold flow rate. Conversely, the amount of oil recovered by waterflooding only (no alkali) initially increased with increasing flow rate up to the same threshold flow rate beyond which there was no difference between the alkaline flood and a waterflood. Copyright 2000 Academic Press.     

Unsaturated hydantoin derivatives. 18. Alkaline hydrolysis of 2-thioxo-5-arylidenehydantoins and some of their derivatives

The alkaline hydrolysis of 2-thioxo-5-arylidenehydantoins (R = p-NO₂, p-Br, H, p-Me, and p-OMe) and their mono- and dialkyl derivatives proceeds with the formation of arylpyruvic acids, which undergo subsequent decomposition in the presence of oxygen in alkali solutions. 2-Thioxohydantoin, thioparabanic acid, and thiourea were not detected among the reaction products. Side processes involving the oxidation of the thioxohydantoins also take place under these conditions. The rate of hydrolysis of 2-thioxo-5- arylidenehydantoins varies as the concentration of alkali in solution changes, and the log k = f (C_KOH) dependence is S-shaped. The hydrolysis of nonionized hydantoins and their monoanions is a bimolecular reaction and is first-order in substrate and hydroxide ion. The rate-determining step in the hydrolysis is the addition of hydroxide ion to the carbon atom of the C₄=O group.See [1] for communication 17.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 406–412, March, 1979.     

Dynamic Interfacial Tension Behavior of Water/Oil Systems Containing In situ-Formed Surfactants

Time-dependent interfacial tension (IFT) has been investigated for an interfacially reactive immiscible system composed of model-acidified oil and alkaline water. The acidified oil was composed of either lauric acid or linoleic acid dissolved in n-dodecane. Drop volume tensiometry was employed to measure the interfacial tension between the two phases. In the case of lauric acid, the IFT value was found to decrease sharply with increasing alkali concentration, even at low drop formation times. In the case of linoleic acid, the IFT decrease with the drop formation time was more gradual, especially at low alkali concentration. The rate of formation of the interfacial area was also found to be dependent on alkali concentration.