Removal of perchlorate anion from water using an anion-exchangeable Zr metal–organic framework UiO-66 containing chloride-coordinated defect sites

Abstract Perchlorate (ClO4−) is a serious inorganic contaminant. This study demonstrated that the Zr-based metal–organic framework UiO-66, containing chloride-coordinated defect sites (Cl-D-UiO-66), has excellent perchlorate-removal properties. Compared with the commercially available anion-exchange resin Purolite A530E, Cl-D-UiO-66 participates in rapid perchlorate removal from water, associated with a maximum removal capacity of 0.55 mmol g−1. The mechanism for perchlorate removal by Cl-D-UiO-66 involves anion exchange between chloride and perchlorate, which competes with simultaneous anion exchange between chloride and bicarbonate. The treatment of recovered Cl-D-UiO-66 with a high concentration of aqueous NaCl solution causes deteriorated removal properties due to a decreased crystallinity. Breakthrough tests using an Cl-D-UiO-66-embedded filter demonstrated that perchlorate removal can be performed under continuous flow conditions, indicating its suitability for commercial-scale utilization.