Dispersion Technology, Inc.

Philip J Goetz

Andrei S Dukhin

Stanislav S Dukhin

Matthias Thommes

Propagation of ultrasound through a porous body saturated with liquid generates electric response. This electro-acoustic effect is called 'seismoelectric current', whereas reverse version, when electric field is driving force, is 'electroseismic current'. It is possible to measure seismoelectric current with existing electro-acoustic devices, which had been designed for characterizing liquid dispersions. Such versatility allows calibration of said devise using dispersion and then applying it for characterizing porous body. In general, magnitude of seismoelectric current depends on porosity, pore size, zeta potential of pore surfaces and elastic properties of matrix. It is possible to adjust conductivity of liquid for simplifying these dependences. For instance, liquid with high ionic strength causes double layers become thin comparing to the pore size, which eliminates dependence of said currents on pore size. We suggest using such case for characterizing porosity. Magnitude of the said currents is proportional to zeta potential. This parameter can be calculated when porosity is known. In contrary, saturation of porous body with low conducting liquid leads to complete overlap of double layers, which can be used for characterizing pore size. Phase of the said currents can be used for determining iso-electric point because it rotates 180 degrees when liquid composition varies through this point.

Method for determining porosity, pore size and zeta potential of porous bodies

A method is described which applies the combination of Electroacoustic and Complex Conductivity measurements to characterize particle electric surface properties, such as &#x3b6;-potential, and bulk properties, such as the dielectric permittivity, in systems where conductivity data is required for applying an appropriate theoretical model for calculating output parameters from the measured data. In particular, this is important in low conducting systems for which the double layer thickness exceeds the particle radius or in the systems where particles have either high bulk dielectric permittivity or high conductivity.

Method for determining electric properties of particles in liquids by means of combined electroacoustic and complex conductivity measurement

A method is described which applies Acoustic Spectrometry to characterize both the particle size distribution and micro-rheological properties of the structured concentrated dispersions. It suggests to model the structured dispersion as a collection of the spherical particles which are connected together with flexible strings. Oscillation of these strings creates an additional energy dissipation which contributes to the total attenuation. This dissipation is dependent on the second virial coefficient characterizing the flexibility of the strings. It is shown that the value of the second virial coefficient can be calculated from the measured attenuation spectra either for known particle size or together with particle size as adjustable parameter.

Method for determining particle size distribution and structural properties of concentrated dispersions

The process of heavy metals removal from the waste water using silica dispersion without mixing silica dispersion with the waste water. This is achieved due to the membrane device where silica dispersion and waste water stream are separated by membrane with pore sizes smaller that size of the silica particles. The process is organized as counter-flow, which means that silica dispersion and waste water flow in the opposite directions. This provides the maximum utilization of the adsorption capacity corresponding to the adsorbent being in equilibrium with the high initial concentration of the contaminant in distinction from the low utilization when adsorbent works in equilibrium with the low output concentration. In the particular instance the membrane device comprises a lumen of a bundle of hollow fibers with silica dispersion flowing either inside or outside of the fibers and wastewater flowing on the opposite side of the fiber membrane. This process eliminates step of separating silica from the wastewater. It opens way to use colloidal silica as adsorbent with highly developed surface area. Continuous monitoring of the silica particles zeta potential yields information for preventing colloidal silica solidification within the device. Solidification of the colloidal silica afterwards solves problem of untreated residual discharge.

Method for the removal of heavy metals from aqueous solution by means of silica as an adsorbent in counter-flow selective dialysis

A method is described which applies Acoustic Spectrometry to characterize both the particle size distribution and mechanical properties of the soft particles in concentrated dispersed systems. It is shown that compressibility of the soft particles can be calculated from the measured sound speed using well-known Wood expression. The value of the thermal expansion coefficient can be calculated from the measured attenuation spectra either for known particle size or together with particle size as adjustable parameter.

Method for determining particle size distribution and mechanical properties of soft particles in liquids

A &ldquo;coupled phase model&rdquo; is used to characterize the motion induced by a sound wave of a particle relative to its dispersion medium. A Kuvabara cell model is used to describe the hydrodynamic effects, whereas a Shilov-Zharkikh cell model is used to characterize electrokinetic effects. A different approach for interpreting the experimental data is described in which the electroacoustic sensor is treated as a transmission line with various energy losses due to the reflection and sound attenuation. The experimental output is also expressed as a loss, namely the ratio of the Colloid Vibration Current to the gradient in the acoustic pressure, and is computed by subtracting all other known losses from the total loss of the electroacoustic sensor. These other energy losses can be either calculated or measured directly using reflected pulses.

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Philip J Goetz