MIL-53 and its OH-bonded variants for bio-polyol adsorption from aqueous solution

The adsorption of bio-polyols from dilute aqueous solution is important but faces challenges in the sustainable bio-refinery process. One solution to increase adsorption efficiency is to leverage hostguest interactions between the polyols and materials to grant a preference for polyols. In this study, we synthesized MIL-53 and diverse OH-bonded variants, and studied their adsorption properties towards ethanediol, 1,3-propanediol and glycerol in water. Among the four materials, OHMIL-53 exhibited fast adsorption kinetics and high capacity, and could be completely regenerated through ethanol elution. Hydrophobic interactions between the alkyl chains of the polyols and the organic linkers of OHMIL-53 and hydrogen bonding interactions between their OH groups were identified. The synergistic effect of the hostguest interactions is responsible for the unique adsorption performances of OHMIL-53 towards polyols, and particularly for 1,3-propanediol. Delicate hostguest interaction drives OH-bonded MOF to capture bio-polyols from diluted aqueous solution, with high capacity, fast kinetics and recyclability.