Advances in Dye Degradation

Water is necessary for the growth of humans and all other living things. Water is becoming scarce due to industrialization and its rapid growth, and the water ecosystem is negatively impacted by the direct release of wastewater into the environment. The textile, tanning, coating, plastics, paint, printing, and other industries, discharge dyes and pigments into the environment. One major problem is to remove dyes and pigments from industrial wastewater in a inexpensive and environmentally friendly way. Before they are released into the environment, there are several ways to mitigate the situation, including chemical, biological, and chemical oxidation processes. The advanced oxidation process (AOP) is a widely employed technique for eliminating contaminants from water and wastewater. The dye molecules are broken down by a Fenton and Fenton-like mechanism, in which the breakdown of hydrogen peroxide produces hydroxyl radicals. This chapter focuses on the most current advancements and various strategies used in the Fenton and/or Fenton-like processes used to degrade the dye molecules. 

This chapter deals with degrading dyes using Metal-Organic Frameworks as a heterogeneous catalyst. Metal-Organic Frameworks (MOFs) are an excellent material for dye degradation due to their multifunctionalities, such as semiconducting properties, ease of use with controllable structures, high surface area, and enormous active sites. MOFs exhibit a promising photocatalytic activity under UV–visible light irradiation due to band gap presence. Several MOFs show an excellent reusability performance even after a few consecutive cycles. The MOFs used to degrade dyes are classified as bare MOFs (Lewis acid MOF, Brønsted Base MOF), MOFs@SiO2 , magnetic MOFs, MOF nanocomposites, ionic MOFs, bimetallic MOFs, nanoparticles doped MOFs, etc., The mechanism of dye removal and photocatalytic degradation of organic dyes using MOFs and the detailed pros and cons of these materials are discussed in detail.

 Environmental contamination has long been a big problem for the planet. One of the greatest ways to harness the massive amounts of sunshine available is photocatalysis, which may be used to remove dangerous organic pollutants from water and the air. Due to its large band gap (3.2 eV), the golden standard TiO2 catalyst only uses the UV area of the sun, or 5% of it, and cannot absorb all of the solar energy. To attain optimal photocatalytic effectiveness, the photocatalytic materials must efficiently harvest photons from sunlight's visible, NIR, and ultraviolet energies to form photocarriers. Several methods for efficiently forming and separating light-induced charge carriers and absorbing visible and near-infrared light photons from sunlight are compiled in this chapter to provide increased photocatalytic efficiency. Effective tactics, including doping and the fabrication of composite materials, are highlighted to emphasize the distinct physicochemical qualities and photocatalytic enhancement of changed materials that are impacted by band alignment, shape, and defect structures. Despite the discussion of an up-conversion method for NIR light absorption, multiphoton emission, continuous luminescence, photo carrier multiplication, and/or plasmonic processes, in addition to the control of photo-thermo effects, make it difficult to use NIR effectively. To fully use the solar spectrum for enhanced photocatalytic pollutant degradation, the chapter provides an overview of UV, Visible, and/or NIR active catalytic materials based on design, synthesis, and interface engineering.

The 21st century has seen tremendous industrialization in many countries worldwide, making environmental protection and energy conversion important issues. As such, investigations on the decomposition of dye molecules in water for environmental protection and clean energy construction are challenging yet impressive. It is still difficult to create a photocatalyst with a sensible design that is affordable and extremely effective for degrading organic dye contaminants. Our work showcases an incredibly effective “interfacial connection and suitable band gap matching” method to create nano-architecture hybrid catalysts based on Transition metal dichalcogenides (TMDs) built using hydrothermal processes. With its large surface area, colossal energetic sites, and interfacial charge assignment, the TMDs-based nano-hybrid catalyst significantly enhances the catalytic degradation of dye pollutants. This demonstration could provide a new hybrid catalyst that degrades dye molecules more effectively and sustainably when exposed to visible light. Lastly, certain recommendations are emphasized for advancing hybrid catalysts based on transition metal dichalcogenides in the future. 

Environmentally hazardous, synthetic organic substances with a complex structure are known as dyes. A major environmental issue is the removal of dyes from the environment, and many techniques are often employed to break down colors. One thought to be a good replacement for dye degradation is photocatalysis. Various photocatalysts carry out the complete mineralization of colors without generating hazardous by-products. When exposed to UV or visible light, metal nanoparticles' promising catalytic ability allows them to break down dangerous synthetic dyes. Compared to traditional methods, green production of metal nanoparticles is more economical and environmentally benign. This book chapter focuses on using different green synthesized metal nanoparticles to degrade synthetic colors. The photodegradation mechanism presented in this chapter could clarify future uses for dye degradation.

 Among the 7×105 tonnes of synthetic dye manufacturing, 1,000 tonnes of non-biodegradable textile dyes are disposed each year into natural streams and water bodies. Due to rising environmental concerns and awareness, it is necessary to remove dyes (pollutants) from municipal and industrial water effluents using a method that is both efficient and affordable. In this regard, photocatalysis has proven to be a safe, long-lasting, and effective wastewater treatment method with a high potential for color removal. Due to their excellent potential as a photocatalyst to degrade various organic dyes, metal oxide nanoparticles have been hailed as promising materials throughout the past two decades. The fundamentals of photocatalysis, drawbacks of traditional water purification techniques, and strategies for dye decolorization and degradation are all briefly covered in this book chapter. It focuses on the mechanisms in relatively wellunderstood metal oxide photocatalysts. It summarizes recent developments to improve metal oxide NPs photocatalytic efficiency, shape and structural modifications of metal oxide, and immobilization of metal oxide by using various supports to make it a versatile and financially successful dye treatment technology. Then, the conclusion and the outlook for the future were considered and hypothesized, releasing the field for advanced study to be granted for developing a photocatalytic system that can be widely employed for various pollutants.

This chapter presents research on using novel dye-degrading processes in the chemical process industries to prevent the increasing water demand caused by the overuse of water in businesses near farmland. This chapter also describes the dye degradation processes used to treat industrial effluents contaminated with dyes and the associated chemical reactions, benefits, and drawbacks. Commonly employed chemical techniques for treating industrial effluents contaminated with dyes demand more costly chemicals and reagents for dye degradation. Solid precipitates or emulsions are created when the additional chemicals interact or react with the contaminants in the industrial effluents that are contaminated with dye. These products could harm our ecological creatures in a variety of ways. Physiological techniques like membrane filtration, nanofiltration, ultrafiltration, and microfiltration have their membrane pores closed by different pollutants, shortening their lifespan. The primary focus of this chapter is on the dye degradation characteristics of graphene oxide nanocomposite materials that have been mixed or doped with different metal oxides and metal nanoparticles. These days, there is increased interest in carbon-based compounds such as graphene and graphene oxides due to their potential environmental benefits when used in the oil and organic gas industry to purify water. The water purification activity of graphene oxide filters is further increased when combined with photochemical active metal oxide. Another benefit is that they don't require extra chemicals or reagents, which also indirectly control other pollutants, and they use solar energy rather than electrical energy. These graphene oxide nanocomposites are unique because they can regenerate without chemicals once they run out of resources. Its physical and chemical characteristics don't change over many cycles.