Preparation of granular hydrogel composite by the redox couple for efficient and fast adsorption of La(III) and Ce(III)

• Granular hydrogel composite was prepared at room temperature by a facile approach.
• Introducing APT into hydrogel is beneficial for the adsorption of rare elements.
• This adsorbent shows fast adsorption rate and high adsorption capacity.
• This adsorbent can be easily regenerated for succeeding adsorption cycles.

A series of granular grafted hydrogel composites were prepared at room temperature and atmospheric conditions by aqueous radical polymerization initiated by the redox couple Vc/H2O2 using chitosan (CTS) as the backbone, acrylic acid (AA) as the monomer, and attapulgite (APT) as the inorganic component, and the resulting products, labeled as CTS-g-PAA/APT, were then applied as the adsorbent to adsorption La(III) and Ce(III) from aqueous solution. The variables affecting the adsorption capacity for La(III) and Ce(III) were investigated, including the contact time, initial concentration, pH, and APT content, etc. The results show that the as-prepared adsorbent has fast adsorption rate and high adsorption capacity for La(III) and Ce(III) in a wide pH range. The adsorption equilibrium for La(III) and Ce(III) can be reached within 40 min and the maximum adsorption capacity for La(III) and Ce(III) is 333.33 and 243.90 mg/g, respectively. An appropriate addition of APT is beneficial for the adsorption process, Finally, the regeneration ability was evaluated for the hydrogel composite, with the observation that after five consecutive adsorption–desorption cycles, the composite still has a good adsorption capacity for La(III) and Ce(III). These information imply that the hydrogel composite can be used as an effective adsorbent for the removal and recovery of La(III) and Ce(III) from aqueous solution.

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