Thiol-functionalized Zr metal-organic frameworks for efficient removal of Fe3+ from water

Fe3+ is essential for human physiological function. However, excess amounts of Fe3+ are dangerous. Metal-organic frameworks (MOFs) with high porosity, stability, and facile tunability are promising for adsorption and environmental applications. In this study, we show that thiol-functionalized Zr-MOFs can remove Fe3+ with the highest adsorption capacity (481 mg g−1) and fastest kinetics (1.07 g mg−1 h−1) reported so far, to the best of our knowledge. The MOFs, containing a high density of sulfur, are highly selective for Fe3+, rapidly purifying water with excess Fe3+ to a drinkable level. Density functional theory and projected density of states calculations confirm that Fe3+ has the largest adsorption energy on our MOFs compared with the other competitive metals tested. In addition, we find that unpaired d electrons in the Fe3+ contribute to the adsorption. Therefore, the post-functionalized Zr-MOFs with high stability, capacity, kinetics, selectivity, and recyclability are promising adsorbents for the purification of water contaminated with heavy metal ions.