Integration of plasmonic effect into MIL-125-NH₂: an ultra-efficient photocatalyst for simultaneous removal of ternary system pollutants

Industrial effluents often contain mixed metal ions and dyes, and it is difficult to efficiently remove both types of contaminants simultaneously. Here, MIL-125-NH₂@Ag/AgCl composites were for the first time developed through a facile deposition-photoreduction method for simultaneously removing Cr(VI)/Rhodamine B (RhB)/Malachite Green (MG) ternary system pollutants under visible-light irradiation. The capacities of Cr(VI) reduction dramatically increased to 98.4% in the coexistence of RhB and MG compared to that of binary (Cr(VI)/RhB (69.6%) or Cr(VI)/MG (67.5%)) and single Cr(VI) (29%) systems. In the meantime, the degradation efficiencies of dyes especially RhB in the ternary system were also improved compared to that of their individual systems. On the grounds of all the experimental results, it can be concluded that the efficient light-harvesting and electrons migration in MIL-125-NH₂@Ag/AgCl and the synergistic effect of redox reactions between Cr(VI) and dyes hinder the recombination of photo-induced electron-hole pairs, which are responsible for their high photocatalytic activity to eliminate the mixed pollutants. This study provides a new route to construct high-performance photocatalysts for the practical treatment of wastewater containing mixed pollutants.