Contamination of Water Resources by Food Dyes and Its Removal Technologies

Abstract

Food dyes comprise different groups which impart color to a wide range of food products. Food products are mainly purchased and consumed by people because they are nutritive and flavorsome and have an attractive color. Food color stimulates appetite and enhances its esthetic appeal of food on table for customer. With sky rocketing industrialization and modernization, the worldwide production of dyes in 2010 was forecasted to be 2.1 metric tons. It has been estimated that 15% of total dyes produced worldwide are discharged to water bodies which adversely affect aquatic ecosystem. Dyes in water reduces its transparency, thereby declining light penetration in the water, hence influencing photosynthesis which consequently reduces dissolved oxygen which is an alarming situation for both aquatic flora and fauna. Dyes wastewater discharged from huge number of industries like textile, leathers, paint, food, pharmaceutical etc. and deteriorating the aquatic environment and pose threat to living organism. The presence of dye molecules in water channels is an emerging alarm to an environmental scientist. An environmental friendly and self-sustainable treatment method should be explored to address this problem. Therefore, this work elaborates the various methods used for removal and degradation of dyes in water, although some processes have a common shortcoming like production of secondary pollution to the environment. This chapter have tried to highlight the important application of food dyes, their contamination and their toxic effect. Herein we also focus on remediation techniques like separation (adsorption, filtration, etc.) and degradation (chemical, biological and electrochemical oxidation) of dyes in aqueous solution. The mechanism and pros and cons of different methods are explored and discussed briefly.

A Brief History of Colour, the Environmental Impact of Synthetic Dyes and Removal by Using Laccases

“…Reducing the cost of treatment and removing the highest percentage of pollutants before discharged the wastewater into water bodies has been the focus of several studies, including chemical, physical, biochemical, biological and hybrid processes [9,140,143]. In this sense, treatments that combine physical, chemical and biological processes are usual to reducing pollutants in industrial effluents [140,141,144].…”

“…These are non-destructive processes; however, depending on the treatment, difficult to remove and treat hazardous sludge can be generated. However, it is a viable option for dyes that generates more toxic products during their treatment than the original dye [143]. Chemical water treatments are expensive compared to physical or biological.…”

Recent Advances in Biopolymer-Based Dye Removal Technologies

“…Imparting color to consumer goods such as textiles is customary practice in many industries [ 1 ]. Primarily, it is done to make the products aesthetically pleasant, thereby making them more appealing to the consumers.…”

“…Indeed, human eyes are incredibly adept at detecting even miniscule color differences. Color could be one of the important determining factors for the consumers in making purchasing decisions, e.g., a textile garment [ 1 , 2 ]. In fact, humans have always been intrigued by colors.…”

Facile Microwave Hydrothermal Synthesis of ZnFe2O4/rGO Nanocomposites and Their Ultra-Fast Adsorption of Methylene Blue Dye

“…Organic dyes do not easily decompose in the natural environment because of their stable and complex chemical structure [ 2 ]. Dye molecules may block sunlight from entering the water and reduce the dissolved oxygen level in water systems [ 3 ]. They also endanger the lives of animals and humans.…”