Oleate Adsorption at a Nigerian Hematite-Water Interface: Effect of Concentration, Temperature, and pH on Adsorption Density

Abstract

Using "pure" natural hematite selected from a Nigerian quartzite hematitic ore, oleate adsorption densities at the hematite-water interface were determined at varying potassium oleate concentrations, temperatures, and pH, using electrical conductivity measurements. The specific surface area of the pure hematite powder was determined using the method of adsorption of paranitrophenol in aqueous solution. The zero-point-of-charge of the Nigerian hematite was measured by the method of microelectrophoresis. The variation in adsorption density with oleate concentration, temperature, and pH, was studied. Factors considered to determine the variation in adsorption density included hemimicelle and micelle formation, variation in oleate solubility with temperature, and the nature of oleate adsorption at the hematite-water interface. A two-stage adsorption process was suggested to account for the observed variation of oleate adsorption with temperature above ambient.