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

Rahul L Kadam,Yeonhee Kim,Sangil Han,Sanjit Gaikwad,Naresh H Tarte,Mincheol Chang

doi:10.3390/catal10050491

Abstract

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.

Highlights

Industrial activities bring in massive amounts of contaminants into aquatic environments, which may disturb the ecosystem
The chemical grafting method was used for the synthesis of the niobium oxide anchored molybdenum (Nb–O–Mo) metal-to-metal charge transfer (MMCT)
Niobium oxide anchored with a molybdenum catalyst was successfully synthesized using a Schlenk line

Summary

Introduction

Industrial activities bring in massive amounts of contaminants into aquatic environments, which may disturb the ecosystem. Congo red is the most used dye in the textile industry, called benzidine based anionic diazo dye [5]. This dye is harmful to the human body and causes carcinogens and mutagen. Crystal violet (Cv) is commonly used in ink industries to produce colored textiles [6]. This dye interacts with cell membrane surfaces in mammals and enters into cells [7], and excess inhalation causes vomiting, headache, diarrhea, dizziness, and damage to the gastrointestinal tract [8]

Methods

Findings

Discussion

Conclusion