Extraction and recycling utilization of metal ions (Cu2+, Co2+ and Ni2+) with magnetic polymer beads

An effective method was developed to isolate heavy metal ions (Cu2+, Ni2+ and Co2+) from the aqueous solution by the magnetic polymer beads. Meanwhile, the bound metal ions could be completely recovered to actualize their recyclable utilization. The magnetic sorbent was prepared with micro-suspension polymerization and its surface was modified with amino groups. After the adsorption by these magnetic beads, the residual concentrations of these metal ions (Cu2+, Ni2+ and Co2+) could be reduced to 0.537, 1.0 and 0.01 mg L−1, respectively. The corresponding recovery efficiency of the bound metal ions exceeded 98%, which meant the almost all metal ions could be fully recycled without change their valence state and chemical properties. The adsorption equilibrium and kinetics were also studied. It found that the only a monolayer of metal ions was absorbed on the surface of these magnetic beads. The saturated amount of Co2+, Ni2+ and Cu2+ reached to 50.3, 49.6 and 51.7 mg g−1, respectively and each amino group on the magnetic beads could capture a metal ion. The adsorption kinetics became more suitable to be described by pseudo-second-order equation. These magnetic beads displayed higher adsorption capacity towards the metal ions in the pH range of 3–5. In addition, temperature had little effect on the adsorption capacity. The regeneration efficiency of this magnetic sorbent in NaOH solution exceeded 98% and the repeated use of these magnetic beads was much excellent.

► Some metal ions were fully recycled during the purification by magnetic sorbent. ► The concentrations of Ni2+, Co2+ and Cu2+ reduced down to 1 mg L−1 after treatment. ► The recovery efficiency of captured metal ions is more than 99% in acidic conditions. ► The excellent regeneration and reuse of magnetic beads makes this technology more efficient.