Impact of the Ceria Particle Oxidation State on the Collecting Properties of Sophorolipids and Benzohydroxamic Acid

The search for environmentally friendly alternatives to petroleum-based reagents in mineral processing requires fundamental studies of novel chemicals in model mineral systems. In this study, we evaluate the potential of acidic (ASL) and lactonic sophorolipids (LSL) as collectors in the froth flotation of ultrafine ceria, which serves as a model rare earth mineral (REM). We compare these two biosurfactants to a conventional petroleum-based collector, benzohydroxamic acid (BHA), in the flotation of ceria against hematite and quartz particles. Our research shows the effect of the oxidation state of ceria on its interaction with both conventional and sophorolipid collectors, which can serve as a tool for selective separation in the applied chemistry of froth flotation. It was found that the affinity of the metal oxides to the biosurfactants at pH 4 decreases in the order of α-Fe2O3 > CeO2 (red) > CeO2 (ox), where the best collector of ultrafine ceria against hematite is BHA. To support our findings, we study collector–mineral interactions through mini-flotation tests, adsorption density, contact angle, and zeta potential analyses. In addition, we evaluate the stability of the froth during the flotation of the biosurfactants. Our results indicate that modifying the oxidation state of ceria and using sophorolipids hold promise for the sustainable flotation of REM.