Efficient and selective removal of Cr(VI) by the modified UiO-66-NH2 with phenothiazine-N-rhodanine from aqueous solution: Performance and mechanisms

In the past decades, due to the worst effect of hexavalent chromium on human and environmental health, people have been committed to removing hexavalent chromium from industrial wastewater. In recent years, metal organic frameworks (MOFs) adsorbents have attracted more and more attention in the removal of pollutants from water. Here, an efficient and selective adsorbent(UiO-66-PRAA) was prepared by modified UiO-66-NH2 with phenothiazine-N-rhodanine to remove Cr(VI) ion from wastewater. The maximum absorption capacity of UiO-66-PRAA at 303 K and pH = 2 was 333.67 mg/g for Cr(VI). Which is higher than that of bare UiO-66-NH2. Elovich kinetic and Sips isotherm models are more suitable for describing the adsorption process of Cr(VI) on UiO-66-PRAA, which indicates that the process is a chemically controlled multilayer adsorption. In addition, the removal mechanisms include chelation, ion exchange and reduction. The adsorbent still shows good adsorption performance under the coexistence of different ions. The excellent cycle performance of UiO-66-PRAA confirms its high potential in removing Cr(VI) from polluted water. In general, UiO-66-PRAA has been shown well adsorption properties and reusability, and our finding might provide a new idea for developing efficient and reusable adsorbent to remove Cr(VI) from wastewater.