A Review of Environmental Impact of Azo Dyes

Abstract

Green plants are one of nature’s factories, fixing inorganic chemicals into organic compounds through photosynthesis and other reactions. Microbes are one of the nature’s most effective tools, converting organic materials—dead plants and animals—into inorganic forms through decomposition and mineralization. Together, green plants and microbes are responsible for maintaining a balance between the organic and inorganic worlds, but pollutants, such as synthetic dyes, can upset this balance. Compared with synthetic dyes, natural dyes are safer and more environmentally friendly, but they are also costlier and more difficult to apply, so they are not viable in most commercial applications. Azo dyes are low cost and have high intensity and color fastness, so they are the most frequently used class of synthetic dyes. The main threats related to the dumping of untreated azo dyes into the environment come from their primary byproducts––aromatic amines––which result from the cleavage of the central azo bonds, and which have been classified as significant carcinogenic compounds, representing a great risk to humans as well as the environment. To address this threat, the degradation of synthetic azo dyes is showing promise as an approach to treating azo-dye wastewater. In this review, the classification of azo dyes and their color mechanism is presented first, and then an overview of the research on their environmental impacts is provided, including their effects on biochemical and chemical oxygen demand, water ecosystems, plants, and crops. Finally, the legislation and guidelines on azo dyes and their byproducts are discussed. Keywords: azo dyes; climate change; biochemical oxygen demand; chemical oxygen demand; aromatic amines

Eficiência das Nanopartículas de ZnO no Tratamento de Efluente Contendo Amarelo Ouro Remazol

“…Such compounds are widely used in the textile, paper and food industries (Alsantali et al, 2022;Benkhaya et al, 2020;Vaiano & De Marco, 2023). This class of dyes pollutes the aquatic environment, reducing light penetration and solubility, interfering the photosynthetic potential of phytoplankton, altering the pH, increasing biochemical and chemical oxygen demands (Alzain et al, 2023).…”

Synthesis Catalyst of Loading Nano Platinum on Graphene Nanosheets and Photodegradation of Bromophenol blue in Ultra-violet light.

“…Pollution of water by organic contaminants is a main environmental issue worldwide. The expansion of the industrial sector has led to an increase in the sources of water pollution, one of the most known contaminants are dyes [1][2][3] . Wastewater produced from textile dying is considered a huge pollutant causing significant damage to the environment.…”

“…Photocatalysts were synthesized to study the photodegradation bromophenol and reduced in wastewaters. [20][21][22] Graphene is well-known as a monolayer of sp 2 -bonded carbon atoms into a two-dimensional structure, it has been rapidly expanded interest of graphene due to its remarkable properties like high electronic and thermal conductivity, as well as features of transport and mechanical characteristics, in addition, it shows a very high surface area and the modification of textural properties of catalyst layers 23 . In this work, the catalyst nano platinum on graphene nanosheets was synthesized and tested as photocatalyst as used a bromophenol as a case study.…”

Linear Polyethyleneimine-Based and Metal Organic Frameworks (DUT-67) Composite Hydrogels as Efficient Sorbents for the Removal of Methyl Orange, Copper Ions, and Penicillin V

“…Particularly, dyes, heavy metal ions and emergent pollutants scape in different degrees from current wastewater treatment technologies, posing a risk to human health and the ecosystem equilibrium in general [1]. There is no regulation that restricts or determines a limit for the concentration of dyes in industrial effluents, as what is regulated is their use in products such as toys or textiles [2]. In the case of copper ions (Cu 2+ ), the World Health Organization establishes a Cu 2+ limit of 2 mg L −1 in drinking water [3,4].…”