Diversity of Synthetic Dyes from Textile Industries, Discharge Impacts and Treatment Methods

Abstract

Natural dyes have been used from ancient times for multiple purposes, most importantly in the field of textile dying. The increasing demand and excessive costs of natural dye extraction engendered the discovery of synthetic dyes from petrochemical compounds. Nowadays, they are dominating the textile market, with nearly 8 × 105 tons produced per year due to their wide range of color pigments and consistent coloration. Textile industries consume huge amounts of water in the dyeing processes, making it hard to treat the enormous quantities of this hazardous wastewater. Thus, they have harmful impacts when discharged in non-treated or partially treated forms in the environment (air, soil, plants and water), causing several human diseases. In the present work we focused on synthetic dyes. We started by studying their classification which depended on the nature of the manufactured fiber (cellulose, protein and synthetic fiber dyes). Then, we mentioned the characteristics of synthetic dyes, however, we focused more on their negative impacts on the ecosystem (soil, plants, water and air) and on humans. Lastly, we discussed the applied physical, chemical and biological strategies solely or in combination for textile dye wastewater treatments. Additionally, we described the newly established nanotechnology which achieves complete discharge decontamination.

Factors Affecting Synthetic Dye Adsorption; Desorption Studies: A Review of Results from the Last Five Years (2017–2021)

“…Dye removal methods have been summarized in review articles by many authors [5,[80][81][82][83][84][85][86][87][88][89][90][91][92][93]. The importance of removing dyes is driven by a number of factors; they are harmful to health, often mutagenic and carcinogenic, inhibit photosynthetic activity in the aqueous medium, and even at very low levels (<1 ppm) are highly visible and undesirable in water bodies, with color being the most obvious parameter affecting water quality [94,95].…”

Design and Preparation of Biomass-Derived Activated Carbon Loaded TiO2 Photocatalyst for Photocatalytic Degradation of Reactive Red 120 and Ofloxacin

“…The massive levels of pollutants released into water sources worldwide due to increased population expansion and industrial development have generated adverse environmental effects in recent decades [ 1 , 2 , 3 , 4 ]. The effluents from textile industries, particularly synthetic dyes, discharged without proper treatment and management adversely affect our environment in one way or another [ 1 ].…”

“…The effluents from textile industries, particularly synthetic dyes, discharged without proper treatment and management adversely affect our environment in one way or another [ 1 ]. Moreover, synthetic dyes, present in many industrial wastewaters, are highly stable molecules and are difficult to degrade by conventional physicochemical processes [ 2 ]. The dyes and antibiotics in the wastewater of pharmaceutical plants and industrial effluents are among the most serious and hazardous pollutants that must be removed from the wastewater before discharging [ 3 ].…”

Photocatalytic Degradation of Reactive Dyes Using Flyash Supported Ag‐TiO2 Photocatalysts

“…Many dyes are also suspected carcinogens and mutagens. [1,2,7,8] Conventional methods are often found to be inadequate for the treatment of dyes from industrial waste water. For example, biological treatment is a slow process and methods like adsorption or coagulation, while coagulation and adsorption though fast, result in the formation of by-products.…”