Simple preparation of poly(sodium styrene sulfonate) hydrogel for highly efficient removal of La(III) and Ce(III)

In this paper, poly(sodium styrene sulfonate) (PSS) hydrogel was synthesized following a one-step free-radical polymerization with N, N -methylene-bis-acrylamide (MBA) as a cross-linker. La(III) and Ce(III) were effectively removed from acidic aqueous solutions by using PSS hydrogel. FTIR, TGA, XRD, SEM, zeta potential analysis, and XPS were used to characterize the morphology and microstructure of PSS hydrogel. By varying pH, adsorbent dose, contact time, initial La(III) and Ce(III) ions concentrations, and interfering ions, the adsorption behavior of La(III) and Ce(III) ions on PSS hydrogel was studied. According to the experimental data, PSS hydrogel exhibited adsorption capacities above 200 mg·g −1 for La(III) and 180 mg·g −1 for Ce(III) over a wide pH range. Furthermore, adsorption data was simulated using pseudo-first order, pseudo-second order and intra-particle diffusion kinetic equations. For the description of adsorption equilibrium, Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isothermal models were used. According to the results, the Langmuir isotherm equation provided the best fit. Based on the Langmuir isotherm equation, the maximum absorption capacities of La(III) and Ce(III) by PSS hydrogel was 241.0 and 223.7 mg·g −1 , respectively. According to FTIR and XPS analysis, sulfonic acid groups were involved in the adsorption of La(III) and Ce(III) ions. And ion exchange and complexation were the main mechanisms involved. Finally, reusability tests reveal that the PSS hydrogel can be reused 13 times without losing effectiveness.