Simultaneous Degradation and Removal of Cr^VI from Aqueous Solution with Zr-Based Metal-Organic Frameworks Bearing Inherent Reductive Sites

Given the serious harm of Cr^VI to human health, development of efficient techniques for its degradation and subsequent in situ adsorptive removal is highly desirable. Herein, UiO-66 type metal-organic frameworks (MOFs) integrated with various hydroxyl groups (UiO-66, UiO-66-OH, and UiO-66-(OH)₂ ) were successfully explored for the efficient decontamination of Cr^VI from aqueous solution. The abundant hydroxyl groups in organic ligands not only served as reductive sites for the degradation of Cr^VI to less toxic Cr^III but also acted as inherent anchorages for the efficient capture of Cr^III . Thanks to their inherent hydroxyl groups and high porosity, UiO-66-(OH)₂ presented almost complete removal of Cr species in simulated industrial wastewater. The total Cr content could be reduced from 5 ppm to 48 ppb under optimized adsorption conditions, which is much lower than the limits of total Cr in drinking water established by the US Environmental Protection Agency (EPA). These outstanding Cr^VI decontamination features, combined with the exceptional chemical stability as well as high porosity prefigured the great potentials of the current adsorbents for the remediation of real-world Cr^VI -containing industrial wastewater.