Facile synthesis of core-shell phase-transited lysozyme coated magnetic nanoparticle as a novel adsorbent for Hg(II) removal in aqueous solutions.

Adsorption using nanomaterials is considered an effective method for controlling the levels of toxic heavy metal in wastewater. Herein, a novel adsorbent, core-shell phase-transited lysozyme film-coated magnetic nanoparticles (FeO@SiO@PTL) for Hg(II) ions removal from aqueous solutions was explored via facile and fast phase transformation and self-assembly process of lysozyme. The physiochemical properties of FeO@SiO@PTL were investigated using various characterization techniques. The adsorption performances such as kinetics, isotherms, selectivity, the effect of coexisting ions, and regeneration were evaluated. FeO@SiO@PTL showed an extremely high Hg(II) uptake rate and achieved more than 90% equilibrium adsorption capacity in 5 min. Hg(II) adsorption was followed by a pseudo-second-order kinetic model and fitted the Langmuir model by achieving a maximum uptake of 701.51 mg/g. Furthermore, excellent Hg(II) selectivity was obtained in a mixed solution containing various heavy metal ions, along with good chemical stability owing to the high adsorption capacity maintained after five cycles. The adsorption analyses indicated that the amino, imino, amide, hydroxyl, carboxyl, and thiol groups exposed on the surface of FeO@SiO@PTL were vital for Hg(II) removal. Consequently, this work will significantly assist in the development of an easily available, eco-friendly, and selective adsorbent material to remove heavy metal ions from wastewater.