Adsorption of phosphorylated chitosan on mineral surfaces

• A phosphorylated chitosan was synthesized with the hydroxyl groups being substituted.
• The phosphorylated chitosan adsorbs on Mn carbonate by strong chemical bonds.
• The phosphorylated chitosan adsorbs on Cu carbonate by hydrogen bonds.

A chitosan sample was modified by phosphorylation reactions on the hydroxyl site. The chemical structure of the resulting grafted chitosan was studied by Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. The adsorption behaviors of the phosphorylated chitosan on two oxide minerals, copper carbonate (malachite) and manganese carbonate (rhodochrosite) were studied by flotation, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and XPS. It was observed that the phosphorylated chitosan adsorbed more strongly on rhodochrosite possibly through covalent bonds of both the PO group and the POH group with the rhodochrosite surface, but only the POH group was observed to bind with malachite surface possibly through hydrogen bonds. The different adsorption mechanisms led to the flotation of malachite and depression of rhodochrosite using sodium oleate as a collector. The oleate ions could replace the relatively weakly bound phosphorylated chitosan from malachite surfaces, making it floatable in the presence of the phosphorylated chitosan.

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