Magnetic mesoporous imprinted adsorbent based on Fe3O4-modified sepiolite for organic micropollutant removal from aqueous solution

A magnetic molecularly imprinted polymer (MSEP@MIP) adsorbent was prepared by using magnetic Fe3O4-modified sepiolite (MSEP) particles as magnetic carrier for the efficient removal of herbicide atrazine from aqueous solution. The composition, thermal stability, chemical structure, specific surface area, morphology, and magnetic properties of MSEP@MIP adsorbent were characterized by X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) method, scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). Absorption isothermal and kinetics experiments were employed to investigate the adsorption capacity of atrazine onto MSEP@MIP. The prepared MSEP@MIP adsorbent was mesoporous. Compared with magnetic non-imprinted polymer (MSEP@NIP) and MSEP, MSEP@MIP showed greater removal efficiency for atrazine (about 91.3% for an initial concentration of 0.1 mg L−1). Kinetic studies demonstrated that the adsorption process onto MSEP@MIP followed a pseudo-second-order rate equation. Isotherm studies indicated that the atrazine adsorption onto MSEP@MIP was a monolayer molecular adsorption with a maximum adsorption amount of 69.53 mg g−1. Scatchard analysis showed that there are two different kinds of binding sites in MSEP@MIP. Furthermore, the thermodynamics parameters indicated that the reaction between MSEP@MIP and atrazine was physical, exothermic, and nonspontaneous in nature.