Electrosurface Properties of Detonation Nanodiamond Hydrosols as Depending on the Size of Dispersed Particles

The electrosurface properties have been experimentally studied for different monodisperse fractions of hydrosol particles of detonation nanodiamond (DND) obtained by air annealing of particle agglomerates, their deagglomeration by sonication in demineralized water, and subsequent centrifugation of resulting hydrosols. The acid-base potentiometric titration and laser Doppler electrophoresis have been employed to obtain the pH dependences of the surface charge density and electrophoretic mobility of the nanoparticles in hydrosols containing 0.001 M KCl within a pH range of 3.5–10.5. A decrease in the average size of DND nanoparticles leads to an increase in the absolute values of the density of their negative surface charge. The high surface potential values calculated for these DND samples are independent of the nanoparticle size. The absolute values of the electrokinetic charge density, which are an order of magnitude lower than those of the surface charge, increase significantly with a decrease in the particle size.