Encapsulating Fe3O4 into calcium alginate coated chitosan hydrochloride hydrogel beads for removal of Cu (II) and U (VI) from aqueous solutions

- A novel magnetic calcium alginate coated chitosan hydrochloride/Fe3O4 adsorbent was prepared.
- Highly removal efficiency for Cu (II) and U (VI) was observed for the prepared sorbent.
- The adsorption followed pseudo-second-order kinetic model.
- The adsorption fitted well with the Langmuir isotherm model.

The aim of this work was to study the removal of Cu (II) and U (VI) ions from aqueous solutions by encapsulating magnetic Fe3O4 nanoparticles into calcium alginate coated chitosan hydrochloride (CCM) hydrogel beads. ATR-FTIR and XRD analysis data indicated that the CCM composites were successfully prepared. SEM images and EDX spectra showed that Cu2+ and UO22+ ions were adhered onto sorbents. Adsorption properties for removal of both copper and uranium ions under various experimental conditions were investigated. Kinetic data and sorption equilibrium isotherms were also conducted in batch process. The sorption kinetic analysis revealed that sorption of Cu (II) and U (VI) followed the pseudo-second-order model well and exhibited 3-stage intraparticle diffusion model during the whole sorption process. Equilibrium data were best described by Langmuir model, and the CCM composite hydrogel beads showed the estimated maximum adsorption capacity 143.276 mg/g and 392.692 mg/g for Cu (II) and U (VI), respectively. The CCM adsorbent exhibited excellent reusability for five cycles use without significant changes in the adsorption capacity and structural stability. The results demonstrated that CCM can be an effective and promising sorbent for Cu (II) and U (VI) ions in wastewater.