A review of nano-carbon based molecularly imprinted polymer adsorbents and their adsorption mechanism

Abstract Nanocarbon materials have become a class of ideal supports for surface molecularly imprinted materials because of their low density, high strength, environment-friendliness, controllable structure and modifiable surface. Thus, nanocarbon-based surface molecularly imprinted polymer adsorbents (C-SMIPs) have achieved satisfactory performance for the removal and enrichment of organic compound pollutants in liquids. This review summarizes C-SMIPs based on various nanocarbon materials for the treatment of ecological environmental pollutants in water during the last five years. The structural characteristics and adsorption features of these C-SMIPshave been comprehensively and systematically analyzed and compared. It is found that the low limit of adsorption capacity is usually decided by the carbon support while the upper limit depends more on the imprinted layer. Specifically, C-SMIPs based on porous carbon nanospheres or graphene oxide usually have large adsorption capacities. It can also be inferred that the essence of C-SMIP adsorption towards target molecules is physical adsorption at the solid-liquid interfaces, the chemical-like adsorption found in the literature is caused by an extremely strong interaction between active sites and the adsorbate by multiple non-covalent bonds like ionic bonds, hydrogen bonds, electrostatic interactions, and van der Waals forces, which settles the long-standing controversy on the nature of adsorption for C-SMIPs. Moreover, analysis and discussion of the literature provide some theoretical and practical evidence for support optimization, imprinting method amelioration, and adsorption parameter selection, which may promote the development and applications of C-SMIPs.