Removal mechanism of Sb(V) by a hybrid ZIF-8@FeNPs and used for treatment of mining wastewater

Abstract

The removal of antimonate (Sb(V)) species from wastewaters has become a growing concern due to their known genotoxicity and carcinogenicity. In this paper, a hybrid ZIF-8@FeNPs material was synthesized from Zeolite Imidazole Framework-8 (ZIF-8) and zero-valent iron nanoparticles (nZVI) and subsequently used to remove Sb(V) from aqueous solution. Characterization indicated that ZIF-8@FeNPs were successfully synthesized and that the valence state of Sb(V) did not change during the removal process, where adsorption of Sb(V) was facilitated by the high specific surface area and porosity of the hybrid. Advanced characterization also showed that Zn-OH and iron oxides were adsorbed on the material after complexation with Sb(V). Kinetic, isothermal, and thermodynamic modeling indicated that the adsorption process followed pseudo-second-order kinetics, via multilayer adsorption which was spontaneous and endothermic. A Sb(V) removal mechanism based on adsorption was proposed. In mining wastewater containing 1.121 mg·L−1 Sb(V), 89.7 % could be removed by the material. During repeated reuse of ZIF-8@FeNPs for the removal of 1 mg·L−1 Sb(V) through four successive cycles, the removal efficiency was still relatively high (39.1 %) after the fourth cycle indicating good potential for practical applications. In addition, ZIF-8@FeNPs also exhibited magnetic properties, which demonstrated that Sb(V) could be easily recovered from wastewater post removal by ZIF-8@FeNPs.