A simple approach to fabricate granular adsorbent for adsorption of rare elements

A kind of granular hybrid hydrogel was prepared under an ambient temperature in air atmosphere using Fenton reagent as the redox initiator, and its three-dimensional structured polymeric network can be formed by the grafting reaction of acrylic acid (AA) onto hydroxypropyl cellulose (HPC) with attapulgite (APT) as the inorganic component. The resulting granular hybrid hydrogel was marked as HPC-g-PAA/APT and used as the adsorbent to remove the rare earth elements, La(III) and Ce(III). The effects of pH and APT content on the adsorption capacity, as well as the adsorption isotherms and kinetics, were systematically investigated. Finally, the reusability of HPC-g-PAA/APT for La(III) and Ce(III) were evaluated. The results indicate that the adsorption process is pH-independent at pH ≥ 4.0 and can be described using the pseudo-second-order kinetic model. The equilibrium isotherm matches well with the Langmuir model. The adsorbed La(III) and Ce(III) can be desorbed by 0.5 mol/L HCl, with the desorption percentage of 80% for La(III) and Ce(III). After five adsorption-desorption cycles, the adsorption capacity shows a slight decrease (about 15%), implying that the granular hybrid hydrogel can be used as an effective adsorbent for the removal and recovery of La(III) and Ce(III) from aqueous solution.