DETERMINATION OF THE HIGH-TEMPERATURE ZETA-POTENTIAL AND PH OF ZERO CHARGE OF SOME TRANSITION-METAL OXIDES

The zeta potential of a particle (i.e. the potential difference between the outer Helmholtz plane of the electrical double layer formed at the particle/fluid interface and the bulk fluid) is a measure of its surface charge. Typically, measurements of the zeta potential have been made at ambient temperature. This paper provides a brief description of new equipment used to measure streaming potentials of oxides at elevated (235-degrees-C) temperature from which zeta potentials were calculated. Measurements are reported of the zeta potential of simulated colloids (i.e. corrosion products such as magnetite and hematite) typically generated in the operation of nuclear and fossil-fired power plants. Because zeta potentials provide a framework for interpreting the transport and deposition of colloids, measurements also are reported of oxides that could possibly serve as coatings to prevent deposition of corrosion products on selected surfaces in power plants.