One-Pot Synthesis of Magnetic Ni@Mg(OH)₂ Core–Shell Nanocomposites as a Recyclable Removal Agent for Heavy Metals

A surfactant-assisted hydrothermal route has been presented to one-pot synthesized Ni nanoparticles encapsulated in Mg(OH)2 hollow spheres. The diameter of Ni cores and the thickness of Mg(OH)2 shells are about 60-80 and 15 nm, respectively, and the size of a whole composite sphere is approximately 70-100 nm. Benefiting from the ferrimagnetic behavior of Ni cores and the high surface area of Mg(OH)2 shells, Ni@Mg(OH)2 nanocomposites exhibit excellent heavy metals adsorption capacity and recyclable property. The first removal efficiency is almost 100% for target metals, and after five cycles, the adsorption capacity remains 95%. A series of experiments show the adsorption of heavy metal ions on Ni@Mg(OH)2 follows a pseudo-second order kinetic equation and can be described by a Langmuir isotherm model.