ON THE CALCULATION OF ELECTROKINETIC POTENTIAL IN DETONATION NANODIAMOND DISPERSIONS

The applicability of various approximations of the theory of electrophoresis for calculating the electrokinetic potential in real nanodisperse systems was evaluated on the example of the polydispersed aqueous sol of thermooxidized detonation nanodiamond containing aggregates of nanoparticles, depending on the concentration and pH of background electrolyte solutions (NaCl). It was found that at low potentials |ζ| < 25 mV calculated for the primary particles in the framework of the Wiersema’s model, taking into account particle aggregation and aggregate porosity practically does not affect the electrokinetic potential. In the range |ζ| 25-50 mV, the most reliable values of the electrokinetic potentials of aggregates seem to be obtained using the Miller’s equation for ion-conducting particles, taking into account their real porosities providing that the potential is constant. At |ζ| > 50 mV, knowing the real size of the aggregates, assuming that they are monolithic, the Overbeek’s equation with Oshima’s analytical expressions of the functions f(κr) and f(κr) can be used to calculate the electrokinetic potentials.