Current Trends in the Utilization of Photolysis and Photocatalysis Treatment Processes for the Remediation of Dye Wastewater: A Short Review

Abstract

Development in the textile industry leads to an increased demand for the use of various dyes. Moreover, there is the use of some dyes in the food industry as well as medical diagnostics. Thereby, increased demand for dyes in various fields has resulted in dye-containing wastewater. Only a small portion of the generated wastewater is adequately treated. The rest is usually dumped or otherwise directly discharged into the sewage system, which ultimately enters rivers, lakes, and streams. The handling and disposal of such concentrated wastewater, especially the dye-containing wastewater, is considered to be a major environmental issue from the moment of its generation to its ultimate disposal. Conventional water treatment methods such as flotation, filtration, adsorption, etc., are non-destructive physical separation processes. They only transfer the pollutants to other phases, thereby generating concentrated deposits. The advanced oxidation process (AOP) is one of the most effective emerging methods for the treatment of wastewater containing chemical pollutants. The method involves the formation and interaction of highly reactive hydroxyl radicals under suitable activation conditions. These radicals are non-selective and efficient for the destruction and eventual mineralization of recalcitrant organic pollutants. This review aims at the pros and cons of using photocatalysis as an efficient AOP to degrade dye-containing wastewater.

Microwave Synthesis of Visible-Light-Activated g-C3N4/TiO2 Photocatalysts

“…Consequently, the scientific output on the topic of dye removal has grown over the last few years [ 10 ]. Dyes can be divided into different groups according to their chemical structure, type of application [ 11 ], and they can also be separated into anionic, cationic and non-ionic dyes [ 11 ]. The largest and most important group of organic dyes is the azo dyes class [ 9 ].…”

“…However, their major drawback is the increased sludge formation volume. Moreover, filtration methods, for instance, typically require high maintenance costs, which does not make them cost effective [ 11 ]. Biological treatments are generally considered an inexpensive and eco-friendly alternative to physical methods, consisting of dye degradation through the metabolic pathways or adsorption of living/dead biomass [ 15 ].…”

Photocatalytic properties of ZnO nanoparticle coating on porous ceramic substrates with varying porosities produced from fly ash and red mud

“…It is preferable to use the sol-gel process since it is simple to alter the crystal structure and form. ZnO nanostructures such as nanotubes, [3][4][5][6][7][8] nanorods, 3,[9][10][11] and nanoparticles 1,[12][13][14][15][16][17][18] have been used as photocatalysts in several works. However, because nanoparticles have a high surface area to volume ratio and accordingly a high surface energy, agglomeration is the most technological obstacle in the use of nanoparticles.…”

Synthesis of high yield, crystalline and thermally stable rare earth (Sm, Eu, Gd) oxide square nanoplates for near-infrared light activatable photocatalysis

“…Traditionally, textile wastewater has been treated using conventional methods including membrane separation, decolorization, natural aerobic treatment, and chemical coagulation. 4,5 However, these methods have disadvantages such as long processing times, chemical instability, high operational costs, separation difficulties, and large amounts of sludge. 6,7 To this end, nanomaterial-mediated photocatalytic dye degradation is a promising technology for pollutant treatment, as it offers a cost-effective and environmentally friendly alternative to traditional methods.…”