Surface chemical characterization of bastnaesite through Electrokinetics

Abstract

The surface properties of the synthesized Ce-bastnaesite were determined by the electrophoresis technique. The point of zero charge (PZC) of this mineral occurs at pH 7.8 A sample of natural bastnaesite [(Ce, La) FCO3] from the Mountain Pass deposit in California, USA was also studied through electrokinetic measurements. The mineral was found to behave essentially like a carbonate with its PZC occurring at pH 9.2 and pCO3 6 in aqueous solutions. The isoelectric point of synthetic Ce-bastnaesite as obtained by equilibrium pH measurements occurs around pH 7.8, which agrees reasonably well with the equionic point of pH 7.3, computed on the basis of thermodynamic data and pH of minimum solubility for Ce bastnaesite, namely pH 7.6 Measurements reported in the literature on relatively pure samples of bastnaesite do exhibit PZCs closer to the value of pH 7.8, as measured by us for synthetic Ce-bastnaesite.