Catalytic Degradation of Organic Dyes in Aqueous Medium

Abstract

Water pollution by the textile industry is an emerging issue. Textile industry is the major industrial sector which contributes to water pollution. Textile industry releases a huge amount of unfixed dyes in wastewater effluents. About 20% of the dye production all over the world is discharged as waste in industrial effluents by textile industry. These dyes are highly stable and colored substances which disturb the aqueous ecosystem significantly. Therefore, there is a need for methods to remove organic dyes from textile industrial effluents. Photo catalysis and catalytic wet oxidation are best practices for degradation of dyes in wastewater. In photo catalysis, the dye molecules can be completely degraded into inorganic non-toxic compounds by irradiation of the dye solution under visible or ultraviolet light in the presence of semiconductor metal-oxide photo catalysts. In catalytic wet oxidation, various metal-based catalysts in supported or unsupported form can be used as heterogeneous catalysts for degradation of dyes in the presence of oxygen or hydrogen peroxide. These processes have several preferences like easy separation of the catalyst from reaction mixture and recycling of the catalyst.

Recent Advances in Plasmonic Photocatalysis Based on TiO2 and Noble Metal Nanoparticles for Energy Conversion, Environmental Remediation, and Organic Synthesis

“…[218,219] However, organic dyes are common molecules to investigate pollutant degradation due to their significant use in industrial and pharmaceutical companies and the reason that they are largely discharged into wastewater. [220][221][222][223][224][225] In the last few years, several methodologies have been developed to enhance the light absorption capabilities of TiO 2 in VIS as well as in NIR regions. [69,226,227] The use of the plasmonic NPs provides an efficient approach to efficiently harvest the VIS light thereby enhancing the charge carrier separation in the adjacent semiconductor.…”

Hydrogels Based on Poly([2-(acryloxy)ethyl] Trimethylammonium Chloride) and Nanocellulose Applied to Remove Methyl Orange Dye from Water

“…About 3500 different types of synthetic dyes are used in the textile industry. The most commonly used dyes are anthraquinone and azo dyes and more than 60% of these dyes are reactive [ 55 ]. These chemical species are released through the industrial processes of dyeing and washing, among others [ 56 ], resulting in wastewater with high concentrations fluctuating between 350–1000 mg L −1 of dyes [ 4 , 57 , 58 ].…”

Perspectives of Organic Dyes Cosensitization and Its Utilization in TiO2 Nanoclusters for Photocatalysis Applications

“…Nanoclusters (NC) are aggregates of countable particles that can exist in a gas or condensed phase; that is, they do not have a stable ligand shell [49]. The nanoclusters act as catalysts designed to increase the sensitivity and reduce the detection time, since TiO 2 is a bandgap semiconductor, Figure 8 illustrates selected TiO 2 nanoclusters [50]. The working principle of DSSC is based on the absorption of light by dyes immobilized on TiO 2 anatase nanoparticles [53].…”