Templating precise multiple binding sites: Promising molecularly imprinted membrane orchestrated by sequential surface imprinting strategy

Abstract

Olive mill wastewater (OMW) is a hazardous environmental effluent due to its high phenolic compounds (PCs) content. Novel strategies affording molecular precision and functional versatility are needed to recover PCs and reduce ecotoxicity. Luteolin (LTL) was selected as a typical PC in the OMW. In this study, we outlined a molecularly imprinted membrane (MPL@CSMIMs) orchestrated by a sequential surface imprinting strategy to selectively separate LTL. Dopamine (DA), as a multifunctional monomer, could self-polymerize in an alkaline solution to form the first LTL-imprinting procedure. A polydopamine (PDA) modulated bottom-up approach was regarded as a molecular linker to enhance the hydrophilicity and binding activity, as well as established a strong and stable adhesion platform for integrated structure. The second imprinting procedure was formed by atom transfer radical polymerization (ATRP). The covalent and non-covalent functional monomers (boronic acid and amino groups) were introduced to create the tailor-made second-imprinted sites. Adsorption isotherm and dynamics, permeation selectivity, and stability were investigated, possessing desirable rebinding ability (49.63 mg g−1) and permselectivity factors (βAGN/LTL = 5.80, βCTC/LTL = 12.82), respectively. In-situ diffuse reflection infrared Fourier transform spectroscopy (In-situ ATR-FTIR) analysis, molecular simulation, and X-ray photoelectron spectroscopy (XPS) analysis revealed that the templating precise adsorption property for LTL was mainly realized by the shape of LTL-imprinted sites and synergistic covalent and non-covalent interactions. Compared to one-step or one-pot imprinting approaches, the proposed sequential surface imprinting strategy offered a more flexible and precise combination to improve the selectivity of MIMs significantly. The efficiency of the sequential imprinting approach made it a competitive and appealing method to develop MIMs.