Hydrophilic imprinted MnO2 nanowires “coating” membrane with ultrahigh adsorption capacity for highly selective separation of Artemisinin/Artemether

The selective separation and purification of ART and ARE using molecularly imprinted membrane (MIM) has attracted considerable attention, but most of conventional blending MIM face low adsorption capacity and poor selectivity due to the blockage of imprinting sites. Herein, an alternative ART imprinted MnO2 nanowires "coating" membrane (MINM) with hydrophilicity was fabricated by vacuum filtration of imprinted MnO2 nanowires and graphene oxide nanosheets on PVDF membrane surface for selective ART separation. For the MINM, the imprinted MnO2 nanowires coating offers more available exposed imprinting sites on the MINM surface compared to that of the blending MIM, while the introduction of graphene oxide improves the hydrophilicity of MINM, significantly reducing the non-specific absorption. Consequently, the MINM exhibits ultrahigh ART adsorption capacity and selectivity, with the ART adsorption amount of 335 mg g−1 at 5 min using dynamic cross-flow separation system, about 12.18 times higher than that of ARE (27.5 mg g−1), and the separation factor (a) value of 12.39. Moreover, the ATR FT-IR dynamic spectrum discloses the in-situ formation of H-bond between ART and MINM, playing a key role in the selective adsorption process. This work provides an alternative strategy to prepare "coating" MIM for high-efficient and selective separation of complex analogue systems.