Histidine-mediated dendritic mesoporous magnetic ion-imprinted polymer toward effective and recoverable cadmium removal

In this study, a magnetic dendritic mesoporous silica nanoparticle material (MDMS@MAH-Cd-IIP) was prepared via surface ion-imprinted technique for selective removal of Cd(Ⅱ) from aqueous solution. The material was based on an ion-imprinted copolymers of 4-vinyl pyridine (4-VP) and N-methacryloyl-L-histidine (MAH), a synthesized ligand monomer to complex with cadmium ions as ion recognition layer. The obtained polymer was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and magnetic measurement system. The adsorption experiments exhibited MDMS@MAH-Cd-IIP showed fast (within 35 min) and selective capture of Cd(Ⅱ) with maximum uptake capacity of 21.04 mg g−1. The adsorption process followed pseudo-second order kinetic and Langmuir adsorption isotherm models, indicating monolayer chemisorption on homogeneous sites was the rate-limiting step. Meanwhile, the MDMS@MAH-Cd-IIP also showed a specificity recognition ability for Cd(Ⅱ) using analogues Co(Ⅱ), Pb(Ⅱ), Zn(Ⅱ) and Ni(Ⅱ) as interference. Moreover, the MDMS@MAH-Cd-IIP based magnetic SPE can extract approximately 90.0–102.0% of Cd (Ⅱ) in real water samples with a RSD of 3.34–8.23%, which indicated the polymer had the high stability and reproducibility and presented itself a promising material for the Cd(Ⅱ) adsorption and detection from aqueous solution.