Ion Imprinted Polymer Monoliths as Adsorbent Materials for the Removal of Hg(II) from Real-Time Aqueous Samples

Ion imprinted polymer monoliths (IIMs) for the adsorption of Hg(II) ions in tablet form were prepared by forming a mercury ion (template ion) complex with 2-(methacryloyloxy)ethyl trimethylammonium cysteine (ligand) and thermally copolymerized with a monomer (methacrylic acid), cross-linker (ethylene glycol dimethacrylate), initiator (benzoyl peroxide) and porogen (acetonitrile) in the polyethylene tube (drinking straw) as a mould. The formed composite was thoroughly characterized by means of FTIR, TGA, FESEM and BET, and further tested by applying the changes in solution pH, concentration, contact time, recycle test and selectivity. The analysis revealed that the activity of the materials was maximum at pH 4.7 and adsorption capacity of Hg(II) by IIMs followed the Langmuir isotherm model. The adsorption equilibrium was achieved after 120 min and followed the second-order reversible kinetics. In addition, we found that the IIMs were reusable up to 15 cycles and exhibited good selectivity towards the Hg(II) ions even in the presence of other interference ions such as Pb(II), Cd(II), As(II) and Cr(III). On further testing for the recovery of Hg(II) ions in real-time aqueous samples (contaminated petrochemical and mining industries), the IIM tablets showed higher selectivity and excellent reusability. In summary, we indicate that the IIMs are easy to prepare, possess high levels of permeability, porosity and selectivity, and offer excellent reusability, thereby making them one of the promising candidates for the successful removal of mercury ions from industrial samples.