Zirconium-organic framework as a novel adsorbent for arsenate remediation from aqueous solutions

The removal of arsenic species in water is a global challenge due to its high toxicity and carcinogenicity. In this work, a stable zirconium metal-organic framework (Zr-MOF) has been synthesized for As(V) removal. The Zr-MOF adsorbed As(V) effectively in the pH range of 4–9 with the maximum adsorption capacity of 278 mg g⁻¹. The experimental data modelling suggested a spontaneous adsorption process involving physicochemical forces. The spectroscopic analysis confirmed the binding of As(V) on the Zr-sites via a ligand-exchange mechanism involving Zr[sbnd]OH. Another possible mechanism was the interaction of As(V) with the dissociation of Zr[sbnd]O(linker) sites. These mechanisms were further confirmed by theoretical calculations, where the Zr[sbnd](μ₃-O) bridges (binding energy ∼4.38 eV) bind As(V) more strongly than the Zr[sbnd]O[sbnd]C linkages (binding energy ∼4.11 eV). The material regeneration was successfully carried out with HCl solution, where the regeneration efficacy remained ∼90% for five cycles. Thus, the study provided a detailed investigation on the As(V) adsorption over Zr-MOF.