ELECTRIC DOUBLE-LAYER OF COD - COMPARISON BETWEEN THEORY AND EXPERIMENT

The calcium oxalate dihydrate (COD) is one of the main components of renal calculi. It is therefore interesting to study the electric double layer (edl) of the particles of this substance in aqueous suspension, because the electric state of the solid-liquid interface will determine its aggregation and its stability. The zeta potential values of the COD particles are presented when these particles are in the presence of substances such as: BaCl2.2 H2O, Na2HPO4.2 H2O, Na4P2O7.10 H2O, chondroitin sulphate and sodium heparin. The theoretical model of Nernst-Gouy-Stern-Grahame (NGSG) of the electrical double layer (edl) has been used in attempts to justify the experimental results. It is deduced from this analysis that, when the concentrations of the electrolytes are high, the specific adsorption of certain species is responsible for the variation of the zeta potential of the COD particles.