Cu-Zn bimetal ZIFs derived nanowhisker zero-valent copper decorated ZnO nanocomposites induced oxygen activation for high-efficiency iodide elimination

Studies on the elimination of iodide anions (I−) by Cu-based adsorbents have been conducted for decades, however its unsatisfactory adsorption performance and its non-reusability are still the main obstacles for large-scale practical applications. Here, an efficient technique was proposed for the elimination of iodide using nanowhisker zero-valent copper (nwZVC) decorated ZnO nanocomposites obtained by two steps pyrolysis of Cu-Zn bimetal ZIFs precursors. The as-synthesized materials were extensively characterized and the results clearly revealed that nanoscale ZVC were well-dispersed in the ZnO matrix, and the morphology and the amount of nanoscale ZVC could be tuned by adjusting the molar ratio of Cu/Zn in ZIF precursors. The following batch adsorption experiments demonstrated that the resultant materials exhibited high adsorption capacity of 270.8 mg g−1 under condition of adequate oxygen, as well as high selectivity, strong acidity resistance and an excellent reusability. The mechanism investigations revealed that the elimination of I− by as-fabricated materials involved adsorption process coupled with oxidation, and the existence of nwZVC was responsible for this since nwZVC could activate molecular oxygen to generate H2O2 accompanied by the release of Cu+, thus leading to I− adsorbed by the released Cu+ and oxidized by the H2O2.