Starch adsorption on hematite surfaces: Evidence of the adsorption mechanism dependence on the surface orientation

In this study, the adsorption mechanism of amylopectin molecules on the hematite (112¯0), (11¯00) and (0001) single-crystal surfaces were investigated by surface-sensitive techniques. Our results show evidence of preferential adsorption on the hematite surface planes in the order of (112¯0) > (11¯00) > (0001). Based on these findings, we propose that distinct singly and triply coordinated oxygen atoms on the surface react in pairs by a multisite complexation mechanism to promote the attachment of amylopectin molecules. These results demonstrate the pivotal role of the exposed hematite surface structure–reactivity relationship in starch adsorption and the possible causes of inefficiencies in industrial flotation processes, as well as biomedical and environmentally friendly technologies based on hematite nanoparticles.