ELECTROCHEMISTRY OF THE ZIRCON WATER INTERFACE

The electrokinetic and surface charge behaviours of a very pure natura l zircon sample and a commercial grade zircon have been studied as a f unction of pH and KNO3 concentration. The isoelectric point (IEP) and point of zero charge (PZC) of the natural zircon were determined to fa ll at a pH of 5.7 +/- 0.1 and 5.9 +/- 0.1 respectively. For the commer cial grade zircon the IEP and PZC values were 5.5 +/- 0.1 and 6.1 +/- 0.1 respectively. A triple layer site-binding model was used to descri be the electrical properties of the zircon-water interface. The surfac e charge and the zeta potential have been simultaneously calculated us ing this model and are in good agreement with the experimental data. T he best-fit parameters pertaining to this model have been extracted by using both graphical extrapolation and computational methods. Infrare d and X-ray photoelectron spectroscopy both indicated that kaolinite w as present as an impurity in the commercial grade zircon.