Electrokinetic Sonic Amplitude Method Research Articles

Nanostructure of organic-inorganic composite materials based on polymer hydrogels

The initial stage of gelation of organic-inorganic hybrid hydrogels based on poly(N-vinylpyrrolidone) and the products of hydrolytic polycondensation of tetramethoxysilane has been studied by capillary viscometry. The development of strong bonds between polymer molecules and silica particles in aqueous solutions is proved by the electrokinetic sonic amplitude method. The molecular mass of poly(N-vinylpyrrolidone), the concentration of starting components, and their total amount affect the onset time of gelation in poly(N-vinylpyrrolidone)-water-tetramethoxysilane systems. The general scheme of formation of three-dimensional networks in such systems under the conditions of mutual penetration of poly(Nvinylpyrrolidone) coils is suggested. According to this scheme, nanoparticles of the general formula SiOx(OH)y(OR)z linking poly(N-vinylpyrrolidone) macromolecules serve as junctions of the gel network due to the formation of hydrogen bonds between hydrogens of silanol groups of organosilanes and oxygens of carbonyl groups of poly(N-vinylpyrrolidone).

Effects of Adsorbed Ion Species to Zeta Potentials of Clay Minerals Estimated by an Electrokinetic Sonic Amplitude Method

Effects of Adsorbed Ion Species to Zeta Potentials of Clay Minerals Estimated by an Electrokinetic Sonic Amplitude Method

Electrokinetic sonic amplitude method as applied to studying adsorption of high-molecular-mass compounds at interfaces

It is shown that the regularities of the adsorption of high-molecular-mass compounds on particle surfaces in disperse systems can be studied by the electrokinetic sonic amplitude method. Procedures are developed for calculating parameters of polymer adsorption layers and the quantitative analysis of their structure. The parameters of the adsorption layers are calculated by the example of a hydrophilic polymer, ethyl-hydroxyethylcellulose, and hydrophilic particles of titanium dioxide and iron oxide dispersed in aqueous disperse systems subjected and nonsubjected to an intense mechanical treatment. The treatment of the disperse systems in the field of intense wave vibrations is found to enhance the adsorption interaction.

Study of dispersed system properties by an electrokinetic sonic amplitude method. Part 2. Calculation of polymer adsorbed layer parameters

A new electrokinetic sonic amplitude method is used for studying the physicochemical properties of dispersed systems and features of the absorption of high-molecular compounds at the surface of particles in dispersed systems. Polymer adsorbed layer parameters are calculated, required for analyzing the structure of these layers.

Study of dispersed system properties by an electrokinetic sonic amplitude method. part 1

A new electrokinetic sonic amplitude method is used to demonstrate the possibility of studying the physicochemical properties of dispersed systems and features of the adsorption of high-molecular compounds at the surface of particles in dispersed systems. Procedures are developed for interpreting the results obtained by the new method for calculating the parameters of absorbed polymer layers and qualitative analysis of the structure of absorbed polymer layers.

Organic-inorganic hybrid hydrogels based on linear poly(N-vinylpyrrolidone) and products of hydrolytic polycondensation of tetramethoxysilane

The initial stage of gelation of organic-inorganic hybrid hydrogels based on poly(N-vinylpyrrolidone) and the products of hydrolytic polycondensation of tetramethoxysilane has been studied by capillary viscometry. The development of strong bonds between polymer molecules and silica particles in aqueous solutions is proved by the electrokinetic sonic amplitude method. The molecular mass of poly(N-vinylpyrrolidone), the concentration of starting components, and their total amount affect the onset time of gelation in poly(N-vinylpyrrolidone)—water—tetramethoxysilane systems. The general scheme of formation of three-dimensional networks in such systems under the conditions of mutual penetration of poly(N-vinylpyrrolidone) coils is suggested. According to this scheme, nanoparticles of the general formula SiOx(OH)y(OR)z linking poly(N-vinylpyrrolidone) macromolecules serve as junctions of the gel network due to the formation of hydrogen bonds between hydrogens of silanol groups of organosilanes and oxygens of carbonyl groups of poly(N-vinylpyrrolidone).

Determination of the Zeta Potential of a Filter Cake by Means of Permeation Experiments

So far, the zeta potential has been determined by using the microelectrophoresis method, the ESA (electrokinetic sonic amplitude) method or ultrasonic spectroscopy. A main drawback of these measuring techniques is that the measured potentials can only be understood as approximations. This paper presents a possibility of calculating the zeta potential of a filter cake from permeation experiments by considering the influence of an electric field. Further research work has to be conducted, though, to verify this method.

Determination of electric double layer parameters for spherical silica particles under application of the triple layer model using surface charge density data and results of electrokinetic sonic amplitude measurements

The surface charge density, σ 0, of AEROSIL OX 50 (Degussa) was determined by titration experiments as well as the electrophoretic mobility, μ, using the electrokinetic sonic amplitude method to characterize the electric double layer of spherical SiO 2-particles in dependence on pH and electrolyte concentration. The electrokinetic experiments result in an isoelectric point pH iep 2.4. At the lowest electrolyte concentration investigated a minimum in the μ–pH-plots emerges. Three relationships between μ and the ζ-potential were examined for the evaluation of the experimental data: (i) the Smoluchowski formula, (ii) an equation from O'Brien et al. (J. Colloid Interf. Sci. 173 (1995) 406) for the Dukhin number which includes the contribution of the mobile layer to surface conductivity only, (iii) Dukhin numbers were determined from the results of conductivity measurements under application of the theory of O'Brien and Perrins (J. Colloid Interf. Sci. 99 (1984) 20) with numerical solutions of Kang and Sangani (J. Colloid Interf. Sci. 165 (1994) 195). Here, the contribution of the ions in the stagnant layer is included too. The Smoluchowski formula is not suitable to describe the μ–pH plots in a quantitative manner, specially at low electrolyte concentration. The other two methods taking into account the surface conductivity give a comparable goodness of fit as a result of the multiparameter regression under application of the triple layer model. A significant contribution of the ions in the stagnant layer to surface conductivity follows from the conductivity measurements. This effect results in an increase of the magnitude of the ζ-potential calculated from the electrophoretic mobility in comparison to the Smoluchowski formula.

The role of steric repulsive force in the dispersion of cement particles in fresh paste prepared with organic admixture

The existence of the steric repulsive force has never yet been determined, though the improved dispersibility of solid particles in concrete by adding the organic admixture is considered to be primarily caused by the dispersion of solid particles by the electrostatic repulsive force based on the formation of an electric double layer made of the admixture adsorbing to the surface of solid particles and the increase of the surface potential, and by the steric repulsive force based on the interaction between the adsorption layers of admixture. The authors proved for the first time the existence of the steric repulsive force acting on the surface of cement particles adsorbing the organic admixture by measuring the interactive force between surface of cement clinker adsorbing the admixture with an atomic force microscope, and measuring the zeta potential of fresh cement paste under actual water-to-cement ratio by electrokinetic sonic amplitude method. It is also clarified that the rate of contribution of electrostatic and steric repulsive force to the dispersion of cement and hydrated cement particles differs by the kind of organic admixture.