Synthesis and characterization of Bi2MoO6/MIL-101(Fe) as a novel composite with enhanced photocatalytic performance: Effect of water matrix and reaction mechanism

Abstract

The integration of Bi2MoO6 with MIL-101(Fe) as a novel structure enhanced photocatalytic activity for RhB degradation. Bi2MoO6/MIL-101(Fe) composites were synthesized via the solvothermal procedure and characterized by XRD, EDX, FE-SEM, TEM, FT-IR, BET, TGA, UV–vis DRS, and PL. The optimal molar ratio Bi2MoO6:MIL-101(Fe) equal to 1:1 showed better photocatalytic activity than Bi2MoO6 and MIL-101(Fe) and other heterostructure composites. The effect of pH (5–9), reaction time (60–120 min), catalyst concentration (0.1–0.5 g/L), and dye concentration (10–20 ppm) were investigated on the removal performance of RhB by using central composite face-centered (CCF). In the optimal process factors where the [Catalyst]:0.4 g/L, [RhB]:20 ppm, pH: 6.5, irradiation time: 120 min, the RhB and TOC removal efficiency were 85% and 84.2%, respectively. The holes and superoxide radicals played a major role in the degradation of RhB. The addition of salt (NaCl, Na2SO4, and NaHCO3) at different concentrations (100, 200, 400, and 800 ppm) revealed that the salts have an inhibitory role in the photocatalytic performance. At low concentrations of 100 ppm, the salts had a negative effect on removal efficiency (kPure water = 0.0155 min−1, kNaCl = 0.0075 min−1, kNa2SO4 = 0.0132 min−1, kNaHCO3 = 0.006 min−1). Increasing the salt concentration to 800 ppm caused improved efficiency for NaCl (kNaCl = 0.0141 min−1), while for Na2SO4 this trend was decreasing (kNa2SO4 = 0.011 min−1), and for NaHCO3 sharply diminished (kNaHCO3 = 0.0026 min−1).