Efficient Removal of High-Concentration Dye Pollutants in Wastewater Using Composite Photocatalyst NH2-MIL-125 (Ti)/g-C3N4 Nanosheets Under Visible Light

Abstract

The NH2-MIL-125(Ti)/g-C3N4 nanosheets composite photocatalyst was prepared by one-step solvothermal synthesis and used to remove high-concentration dye wastewater. The morphology, structure, and photoelectrochemical properties of the as-synthesized samples were characterized by XRD, SEM, XPS, FT-IR, UV–vis DRS PL, EIS, and transient photocurrent. The results showed that g-C3N4 nanosheets were tightly loaded on the surface of NH2-MIL-125(Ti) to form the NH2-MIL-125(Ti)/g-C3N4 nanosheets composite photocatalyst. Among them, NM (Ti)/CNNS30 showed the best adsorption performance and photocatalytic degradation activity for removing high-concentration RhB solution. In addition, the optimal experimental conditions were also explored, such as the concentration of RhB solution, the dosage of NM (Ti)/CNNS30, and the initial pH of RhB. Finally, the mechanism of photocatalytic degradation of NM(Ti)/CNNS30 on high-concentration RhB solution was also proposed based on active species capture experiment and energy band structure analysis. It was inferred that O2− and h+ were the main active species for NM(Ti) photocatalytic degradation of high-concentration RhB. This work provided new insights into the design and synthesis of highly efficient photocatalysts for the practical treatment of high-concentration dye wastewater.