Efficient removal of antimonate from water by yttrium-based metal-organic framework: Adsorbent stability and adsorption mechanism investigation

Efficient decontamination of Sb(V) from water has long been an urgent task owing to its grave threat to human health. Herein, Y-based MOFs (MOF-Y and NH₂-MOF-Y) were synthesized for effective adsorption of Sb(V) from aqueous solution, and the stability of the Y based MOFs were estimated. Kinetic and isotherms results indicated that the pseudo-second order kinetic (R² > 0.90) and Langmuir isotherm models (R² > 0.97) quite well described the adsorption of Sb(V) on Y-based MOFs, revealed that the uptake of Sb(V) on Y-based MOFs were followed by a monolayer chemical adsorption process. The maximum adsorption capacities of Sb(V) calculated from the Langmuir model were 161.3 and 151.5 mg/g for MOF-Y and NH₂-MOF-Y, respectively. The Y-based MOFs exhibited strong water and chemical stability, it could be utilized for removal Sb(V) under wide pH range and various concentration of Sb(V). The spent adsorbents could be successfully regenerated by NaCl (5 mol/L) solution for further utilization without damaging the crystal structure of Y-based MOFs. X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS) results revealed that the formation of inner-sphere Y-O-Sb complex between Y-oxo-clusters and Sb(V) was the dominant adsorption mechanism, while the co-precipitation of Y³⁺ and Sb(V) was also partially contributed the Sb(V) adsorption. High stability together with high Sb(V) adsorption capacity and excellent recyclability endow the Y-based MOFs as promising adsorbents for Sb(V) removal from wastewater.