Sandwich structured membrane adsorber with metal organic frameworks for aflatoxin B1 removal

Abstract

Aflatoxins as toxic substances produced by microorganisms widely existed in food crops and detoxification of aflatoxins is highly desired to avoid their leaking into the environment. Herein, a novel combination strategy of metal organic frameworks (MOFs) and porous membrane was used to prepare membrane adsorbent for aflatoxin B1 (AFB1) removal. Firstly, the MOFs particles were readily fixed on a porous membrane by reverse filtration. Subsequently, polydopamine (PDA) coating and further charged polymer grafting were employed for sealing the MOFs particles. By systematically studying four kinds of MOFs particles for AFB1 adsorption, the MIL-100 and the resultant MIL-100 loaded membrane outperformed the other MOFs materials. Through comprehensively evaluating five different sealing approaches, it was found that the charge of the grafted polymers on the membrane was critical for AFB1 adsorption. The PDA/alginate dialdehyde (ADA) modified MIL-100 loaded membrane prepared with PDA coating and ADA grafting for 30 min, could achieve the highest AFB1 removal efficiency of 76.4% and the membrane stability was greatly improved, meanwhile the water permeate flux was barely affected by the additional layers. A good reusability could be realized by a facile desorption process and the AFB1 removal efficiency kept at 61.8% after five reuse cycles. When dealing with real corn juice, the AFB1 removal efficiency in flow-through mode was lower than that obtained in dipping incubation mode, because severer membrane fouling occurred during dynamic adsorption which blocked the adsorption sites on the membrane. The present work not only demonstrated a reliable and effective approach to synthesize robust MOFs-loaded membrane for AFB1 removal, but also offered new insights into micropollutant removal with MOFs derived materials.