| A detailed study has been carried out to investigate the dissolution characteristics of unstabilized and stabilized CrO2 particles. It has been found that on contact of CrO2 with aqueous solutions, it dissolves by disproportionation reaction to HCrO4 and Cr2O3. XPS study has shown that stabilization of CrO2 particles with bisulfite solution leads to the formation of Cr2O3. However, because of agglomeration of the CrO2 particles due to their magnetic properties, not all of the surface is completely stabilized. The electrokinetic characteristics of Cr(IV) and Cr(III) oxides in aqueous solutions have been investigated. Experiments suggest that sulfite ions chemisorb strongly on Cr2O3 particles. Experiments have also been carried out to study the adsorption of sodium dodecyl sulfate (SDS) on Cr2O3 particles. With increasing SDS concentration, Cr2O3 becomes less positively charged and ultimately negatively charged when the surfactant concentration exceeds 10-3 M. This suggests that SDS specifically adsorbs onto the oxide. |
