Impact of the Ceria\nParticle Oxidation State on the\nCollecting Properties of Sophorolipids and Benzohydroxamic Acid

The search for environmentally friendly alternatives\nto petroleum-based\nreagents in mineral processing requires fundamental studies of novel\nchemicals in model mineral systems. In this study, we evaluate the\npotential of acidic (ASL) and lactonic sophorolipids (LSL) as collectors\nin the froth flotation of ultrafine ceria, which serves as a model\nrare earth mineral (REM). We compare these two biosurfactants to a\nconventional petroleum-based collector, benzohydroxamic acid (BHA),\nin the flotation of ceria against hematite and quartz particles. Our\nresearch shows the effect of the oxidation state of ceria on its interaction\nwith both conventional and sophorolipid collectors, which can serve\nas a tool for selective separation in the applied chemistry of froth\nflotation. It was found that the affinity of the metal oxides to the\nbiosurfactants at pH 4 decreases in the order of α-Fe<sub>2</sub>O<sub>3</sub> > CeO<sub>2</sub><sup>(red)</sup> > CeO<sub>2</sub><sup>(ox)</sup>, where the best collector of ultrafine ceria against\nhematite is BHA. To support our findings, we study collector–mineral\ninteractions through mini-flotation tests, adsorption density, contact\nangle, and zeta potential analyses. In addition, we evaluate the stability\nof the froth during the flotation of the biosurfactants. Our results\nindicate that modifying the oxidation state of ceria and using sophorolipids\nhold promise for the sustainable flotation of REM.