Effect of calcium ionic concentrations on the adsorption of carboxymethyl cellulose onto talc surface: Flotation, adsorption and AFM imaging study

Abstract

The effect of various calcium ionic concentration on the adsorption of carboxymethyl cellulose (CMC) onto talc surface has been investigated using flotation tests, adsorption measurements and tapping mode atomic force microscopy (AFM) imaging. Microflotation tests indicated that the depression of talc depressed by CMC was increasingly enhanced with the increase of Ca2+ at pH 8.5. And within the pH range of 2–11.5, in the presence of Ca2+, the depression of talc by CMC could be facilitated by Ca2+ stably. Adsorption experiments confirmed that with the increase of Ca2+, the adsorbed CMC on talc increased at pH 8.5. AFM imaging revealed the morphology of adsorbed CMC were different in the absence and presence of various Ca2+ ions concentration. In the absence of Ca2+ ions, the morphology of adsorbed CMC consisted of randomly distributed salient point domains with a lower area fraction of surface coverage; in the presence of 10−4 mol/L Ca2+ ions the morphology mingled with salient point and reticulate adsorption; in the presence of 10−3 and 10−2 mol/L Ca2+ ions the morphology is a reticulate multilayer adsorption with a higher area fraction of surface coverage.