Engineered zinc-aluminum layered double hydroxide/zeolitic imidazolate framework-67 integrated with polydopamine functionalized sodium alginate hydrogel microsphere for synergistic adsorption performance of europium and lead from wastewater

Recyclable LZPS hydrogel microspheres were successfully synthesized. • LZPS microspheres revealed remarkable adsorption capacity towards Eu(III) and Pb(II). • LZPS microspheres displayed excellent stability in removal of Eu(III) and Pb(II). • Long-term field studies on Eu(III) and Pb(II) behaviors in medium were required. • Multicomponent synergy enhanced adsorption capacity and ion selectivity. With the fast growth of the nuclear industry and application of radioisotopes, the pollution of aquatic environments with radionuclides and heavy metals has become increasingly severe. Thus, there is a pressing demand to develop novel adsorbent materials with high efficiency, high selectivity, and good recyclability. Herein, a novel zinc-aluminum layered double hydroxide/zeolitic imidazolate framework-67 integrated with polydopamine functionalized sodium alginate hydrogel microsphere (Zn Al-LDH/ZIF-67/PDA/SA, denoted as LZPS), was successfully synthesized to achieve the efficient enrichment of Eu(Ⅲ) and Pb(Ⅱ). As revealed by characterization measurements, the hydrogel microsphere was successfully constructed with abundant surface functional groups contributing to the prominent adsorption behavior of the adsorbent. The impact of diverse environmental factors on the adsorption behavior of LZPS for Eu(Ⅲ) and Pb(Ⅱ) in wastewater was systematically examined through macroscopic experiments. The experimental conclusions demonstrated that LZPS exhibited excellent adsorption capability toward Eu(Ⅲ) and Pb(Ⅱ). Adsorption equilibrium for Eu(Ⅲ) and Pb(Ⅱ) was attained within 150 min, and the pseudo-second-order model offered a satisfactory description of the adsorption kinetic data. At 303 K, the maximum adsorption capacity of Eu(Ⅲ) and Pb(Ⅱ) using Langmuir model was 2.10 × 10 −3 mol/g and 9.28 × 10 −4 mol/g, respectively. It was confirmed by XPS analysis that Eu(Ⅲ) and Pb(Ⅱ) adsorption on LZPS was predominantly driven by electrostatic interaction, ion exchange, surface complexation, and reduction reaction. Overall, the LZPS hydrogel microsphere was possessed significant application prospects and potential practical value for the efficient treatment of Eu(Ⅲ) and Pb(Ⅱ) in nuclear wastewater. Download: Download high-res image (236KB) Download: Download full-size image