Catalytic Decolorization of Rhodamine B, Congo Red, and Crystal Violet Dyes, with a Novel Niobium Oxide Anchored Molybdenum (Nb-O-Mo)

In this work, a new metal-to-metal charge transfer (MMCT) heterogeneous catalyst (Nb-O-Mo) was synthesized by a chemical grafting method under an inert atmosphere. The activity of the covalently anchored oxo-bridged Nb-O-Mo catalyst was estimated for decolorization of Rh B, congo red, and crystal violet dyes in an aqueous solution under fluorescent light. The catalyst was characterized via X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectrometer, Fourier-transform infrared, and FT-Raman. The catalytic decolorization was evaluated from the UV spectra of dyes in aqueous solution by changing different factors, including dye concentration, temperature, and catalyst loading. Decolorization percentages were 83%-89%, 86%-95%, 97%-99% for Rh B, Congo Red and Crystal Violet in 1 min at 298 K, showing the best performance among other catalysts. Decolorization efficiency for 50 ppm of Rh B was improved from 92% to 98%, with a temperature increase to 318 K.