Synthesis and application of a highly selective molecularly imprinted adsorbent based on multi-walled carbon nanotubes for selective removal of perfluorooctanoic acid

Abstract

In this work, a kind of novel surface molecularly imprinted polymers (MIPs) based on multi-walled carbon nanotubes (MWCNTs) for selective removal of perfluorooctanoic acid (PFOA) was prepared using PFOA as the template, acrylic amide (AAM) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the crosslinker agent, respectively. The results of characterization indicated that MIPs have been successfully grafted onto the surface of MWCNTs with high thermal stability. Batch adsorption experiments were conducted to evaluate the adsorption kinetics, isotherms, effects of pH on the adsorption and selective recognition of MWCNTs@MIPs. The adsorption reached equilibrium at about 80 min following a pseudo-second order model. By further analyzing the kinetic data using an ion diffusion model, the results suggested that the adsorption was mainly controlled by internal diffusion of particles. The adsorption isotherm could be well fitted using the Langmuir isotherm model with a maximum adsorption capacity of 12.4 mg g⁻¹ for PFOA. Additionally, no significant deterioration of the adsorption capacity for PFOA adsorbed onto MWCNTs@MIPs was observed after five cycles of regeneration. Finally, the MWCNTs@MIPs showed high selective recognition of PFOA both in lab and practical applications.