Conductometric and gravimetric studies of the kinetics of graphite sedimentation in aqueous dispersions

The kinetics of graphite sedimentation in aqueous dispersions is studied using conductometric and gravimetric techniques. Triton X-305, a nonionic surfactant, is used to regulate the aggregation of hydrophobic graphite particles and to stabilize the system. The differences in the kinetics of the change in the weight and conductivity of sediments depending on the surfactant concentration are discussed. It is shown that insulating films of low conductivity are formed around particles at a concentration corresponding to coating of graphite particles with a monolayer of the surfactant and the conductivity of the sediments sharply decreases. At a higher surfactant concentration, which corresponds to the critical micellization concentration, compact sediments are formed; their conductivity first decreases and then increases in the process of restructuring. The change in the sediment structure as a function of the surfactant concentration is discussed.