An ion-imprinted polymer based on the novel functional monomer for selective removal of Ni(II) from aqueous solution

An unfamiliar functional monomer 2-(Allylmercapto) nicotinic acid (ANA), which contains both N and S groups that have a strong coordinating ability with nickel ions, is used for imprinting Ni(II). The obtained Ni(II) ion-imprinted polymer (Ni-IIP) shows a fast uptake ability for the removal of Ni(II), and its adsorption equilibrium time is less than 20   min. The maximum Ni(II) adsorption capacity of Ni-IIP is found to be 38.85   mg/g, that is, more than double that of non-imprinted polymer (Ni-NIP) (18.38   mg/g), at a temperature of 30   °C and optimum pH of 6. Additionally, the adsorption is a spontaneous and endothermic process according to the obtained thermodynamic parameters. Besides, Ni-IIP shows excellent selectivity factors of 33.63, 219.59, 4.23, 16.89 and 32.74 for Ni 2+ /Zn 2+ , Ni 2+ /Mg 2+ , Ni 2+ /Co 2+ , Ni 2+ /Cd 2+ and Ni 2+ /Cu 2+ , respectively. Moreover, the Ni-IIP used is stable because the adsorption capacity is 82.7% of the initial saturation binding capacity up to the 5th cycle. Most notably, the application of Ni-IIP in wastewater samples shows a high removal efficiency for Ni(II) of more than 93.4%. The results indicate that the Ni-IIP is an effective adsorption material, allowing for the selective removal of Ni(II) from aqueous solutions at high efficiency.