Zr-Based MOFs as new photocatalysts for the rapid reduction of Cr() in water

Hexavalent chromium existing in wastewater has severe toxic effects on the human body. Reductive detoxification and adsorption of hexavalent chromium have increasingly become important research areas. In this study, Zr-based metal-organic frameworks are investigated as new photocatalysts for the photocatalytic reduction of Cr( vi ); the catalysts are expected to integrate the high efficient reductive ability of nano-scale Zr-O clusters with the visible light photoexcitation ability of the OH-containing organic molecules. The designed Zr-based MOFs were successfully synthesized via a facile solvothermal route and then were comprehensively investigated via XRD, FT-IR, SEM, EDS, BET, and TG characterization techniques. The photocatalytic reduction tests demonstrated that the as-synthesized Zr-based MOF materials can rapidly reduce and totally remove Cr( vi ) from water containing 8 ppm Cr( vi ) under visible light using only 10 minutes of irradiation time. Through a comparative photocatalytic reduction examination, it was found that the two OH groups in the organic molecules played a key role in the visible-light photocatalytic reduction process. This study explored a new way to employ high catalytic ability of nano-scale materials by avoiding their agglomeration and photoexcitation ability of organic molecules simultaneously, which will contribute to the research on photocatalytic materials. The hydroxyl modified Zr-based MOFs is used for photocatalytic reduction of hexavalent chromium existing in wastewater.