Temperature-dependent streaming potentials: 1. Theory

The variation of streaming potentials (voltage/pressure cross-coupling coefficient) with temperature is examined with particular emphasis on the effect of temperature on zeta potentials. The variation of streaming potential with temperature cannot be explained solely by the known temperature dependence of water viscosity, permittivity, and conductivity; the change of zeta potential with temperature must also be included. Many previous experimental studies show that the magnitude of the zeta potential increases with temperature. It was found in this study that the increase is controlled primarily by the surface charge density. These changes are influenced by the absorption properties of the surface and thus the surface charge, which in turn affects the Stern layer charge and properties of the electrical double layer. It is found that the slope of the temperature versus zeta potential curve is controlled by the change in enthalpy of the surface reactions. It was also found that viscosity is the most dominant term in the coupling coefficient, but changes in the conductivity model used to determine zeta potentials can also affect streaming potential coupling coefficient results. For the cases studied, the temperature-dependent zeta potential is determined by the temperature-dependent behavior of the Debye-Huckel parameter, 4%; the diffuse layer of electrical double layer (EDL), 6%; and the surface charge, 90%. The Revil and Glover model was able to account for much of the change in the surface charge density caused by changes in temperature.