Abstract
As the acidity increases, certain heavy metal ions in mine water, such as Cr(VI) ions, transition from insoluble compounds to soluble states, increasing their toxicity. Therefore, how to efficiently remove Cr(VI) ions under acidic conditions is an urgent task. Herein, we utilize the coal gangue associated with oil-rich coal mines as the main catalyst carrier. By high-temperature calcination and acid washing of its powder, we obtain a large-pore molecular sieve. Under hydrothermal conditions, we induce the growth and nucleation of water-resistant and acid-resistant MOF (UiO-66-NH(2)) using these molecular sieves as crystal nuclei and carriers, thus forming a composite heterogeneous structure. In this composite heterogeneous material, the molecular sieves, due to their large pores and abundant acidic sites, can accelerate the adsorption and dispersion of Cr(VI) ions. The UiO-66-NH(2) material can efficiently absorb photon energy and convert it into electrons to accelerate the reduction of Cr(VI) ions. At the same time, the combination of the two can increase the efficiency of photogenerated charge carrier separation. This method provides a new approach for the application of coal gangue associated with oil-rich coal and offers a new path for the removal of heavy metals from oil-rich coal mine water.