Zeta Potential of Porous Materials
Propagation of ultrasound through a wetted porous material generates an electric response, known as an electroseismic effect. It can be characterized as a high frequency electroacoustic streaming current. There are several papers dedicated to theoretical and experimental studies of this effect. It turns out that it can be used for characterizing porous materials and, in particular; zeta potential in such materials.
Instrument DT -350 is capable of measuring electroseismic current, both amplitude and phase. It employs the same Zeta potential probe that is part of the DT-300 and 310 models for characterizing zeta potential of concentrated dispersions and emulsions.
Calculation of zeta potential from seismoelectric current requires information on porosity. It is convenient to use a porosity measurement that employs a high frequency AC electric field, since it is already part of the seismoelectric measurement. That is why the DT-350 is equipped with the DTI aqueous conductivity probe that functions at 3 MHz. Details of the porosity measurement are described in the text that is linked to the Model DT-900.