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Recycle of Ag+ and Zn2+ with Magnetic Adsorbent in Process of Its Purification from Wastewater



A highly reusable magnetic polymer beads was employed as adsorbent to extract Ag+ and Zn2+ from aqueous solution. Because of its excellent ability to adsorb Ag+ and Zn2+, after adsorption, the residual concentration of Zn2+ or Ag+ is far lower than the wastewater discharge Standard of China. The pseudo-second-order kinetic model was suitable to describe the responding adsorption behavior. The adsorption isotherm of Ag+ fitted best with Langmuir model, suggesting a monolayer adsorption occurred between metal ions on these magnetic beads. But the adsorption isotherm of Zn2+ could be well described by Freundlich model. From the thermodynamic parameters, it indicated that this adsorption process was endothermic. Furthermore, the binding metal ions on the magnetic adsorbent could be easily recovered by eluting with acidic solution without changing the valance state of these metal ions. Moreover, the responding regeneration of these magnetic beads could be performed in alkali solution. Even after 20 runs of adsorption–desorption–regeneration, the adsorption ability of these magnetic beads changed little. These advantages, including excellent stability, favorable adsorption capacity, simple operation, and prominent recoverability, bring great potential to this technology in the removal of hazardous heavy metal ions from wastewater.