Electrosonic amplitude

Response to Electric and Acoustic Fields. If the stabilization of a suspension is primarily due to electrostatic repulsion, measurement of the zeta potential, can detect whether there is adequate electrostatic repulsion to overcome polarizability attraction. A common guideline is that the dispersion should be stable if f > 30 mV. In electrophoresis the applied electric field is held constant and particle velocity is monitored using a microscope and video camera. In the electrosonic amplitude technique the electric field is pulsed, and the sudden motion of the charged particles relative to their counterion atmospheres generates an acoustic pulse which can be related to the charge on the particles and the concentration of ions in solution (18). 

Electrokinetic sonic amplitude (ESA, also termed electrosonic amplitude), an... 

Hydrous sodium titanate was prepared by the method of Dosch and Stephens (1). Titanium isopropoxide was slowly added to a 15 wt% solution of sodium hydroxide in methanol. The resulting solution was hydrolyzed by addition to 10 vol% water in acetone. The hydrolysis product is an amorphous hydrous oxide with a Na Ti ratio of 0.5 which contains, after vacuum drying at room temperature, approximately 13.5 wt% water and 2.5 wt% residual alcohol. The ion-exchange characteristics of the sodium titanate and the hydrolysis behavior of the nickel nitrate solutions were characterized using a combination of potentiometric titrations, inductively coupled plasma atomic emission (ICP) analysis of filtrates, and surface charge measurements obtained using a Matec electrosonic amplitude device. 

Similarly to the reciprocity that exists between electroosmosis and streaming potential (See Chapter V,5), there is a reciprocity between the ultrasonic waves and the alternating electric field generated by them. That is, the application of the alternating electric field to disperse systems results in the generation of an ultrasound signal, referred to as the electrosonic amplitude (ESA). The ESA is related to the dynamic electrophoretic mobility via a relationship similar to eq. (V.6), namely... 

Figure 23. The G or elastic modulus and the electrosonic amplitude (ESA) of an oil sands fine tailings as a function of pH. The G or response of the suspension structure to nondestructive shear is determined by the strength of the particle floes. The particle interactions or floe formation is a function of the surface charges on the particles (determined by the electrosonic amplitude) and this, in turn, is sensitive to the pH of the system.

The amount of Si ions dissolution is found to be dependent on surface modification, which was confirmed by induchvely coupled plasma-atomic emission spectrometer (ICP-AES) analysis. Table 2.2 shows the dissolution amount of Si ions with and without surface modification of fumed silica slurry. Without surface modification, the amount of Si dissoluhon was 1.370 0.002 mol/L, whereas surfaces modified with poly(vinylpyrrolidone) (PVP) polymer yielded a dissoluhon of 0.070 0.001 mol/L, almost 20 hmes less than the unmodified surface. Figure 2.6 represents the electro-kinetic behavior of silica characterized by electrosonic amplitude (ESA) with and without surface modification. When PVP polymer modified the silica surface, d5mamic mobility of silica particles showed a reduchon from -9 to -7 mobility units (10 m /Vxs). Dynamic mobility of silica particles lacking this passivation layer shows that silica suspensions exhibit negative surface potentials at pH values above 3.5, and reach a maximum potential at pH 9.0. However, beyond pH 9.0, the electrokinetic potential decreases with an increasing suspension pH. This effect is attributed to a compression of the electrical double layer due to the dissolution of Si ions, which resulted in an increase of ionic silicate species in solution and the presence of alkali ionic species. When the silica surface was modified by... 

Electrokinetic sonic amplitude ESA, also termed electrosonic amplitude), an electro-acoustical method involving detection of the sound wave generated when dispersed species are made to move (oscillate) by an imposed alternating electric field (the principal features of the technique are shown in... 

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