Selective adsorption onto fine iron oxide particles of poly(acrylamide)-b-poly(ethylene oxide) terminated by vitamin E

Beneficiation of valuable fine metal oxide particles generated during mining, comminution and processing has long been problematic for the mineral processing industry due to their poor floatability. To overcome this issue, selective adsorption of a polymer onto the target fine particles provides a potential solution. In this study, two novel poly(acrylamide)- block -poly(ethylene oxide) copolymers, featuring a terminal α-tocopherol (vitamin E) moiety, were synthesised by reversible addition-fragmentation chain-transfer (RAFT) polymerisation. These copolymers were designed to selectively target adsorption onto valuable iron oxide particles. The adsorption of the novel copolymers onto hematite, magnetite and silica were then studied via the depletion method. This revealed significantly higher adsorption affinity of the vitamin E-tagged block copolymers onto iron oxide particles over silica. The adsorption was further benchmarked against commercial polyacrylamides (PAMs), a PAM modified with a hydrophobic RAFT agent, poly(ethylene oxide) (PEO) homopolymers and the vitamin E molecule. Isotherms indicate the vitamin E molecule and PEO homopolymers have higher affinity for silica than iron oxide, indicating the selectivity of the novel copolymers for iron oxide is driven by the PAM block. The prospective frother action of the copolymers was determined by measuring surface tension at the air-water interface. Overall, the novel poly(acrylamide)- block -poly(ethylene oxide) copolymers offer a step towards more sustainable mineral processing reagents. • Vitamin E tagged novel polyacrylamide copolymers were designed to act as multifunctional reagents. • Novel polyacrylamides selectively adsorb onto iron oxides against silica. • Adsorption of novel polymers is benchmarked with commercial polyacrylamide homopolymers. • Vitamin E alone has a higher affinity toward silica than iron oxide surfaces. • Stable foam was observed when the copolymers adsorbed at the gas/water interface.