Laccase mediator system as a potential technology for decolorization of textile dyes - Overview and perspectives

Discharge of the exhausted dye bath at the end of dyeing imposes a huge waste-water load, necessitating the use of fresh water for further processing. Due to the limited availability of fresh water, industries are compelled to remove the dyes from drained-out liquor to protect the environment and recycle the treated water for future processing. Discharged dyes create a film or layer of color on the water's surface, impeding the natural breakdown of substances and harm aquatic organisms. A significant proportion of effluent comprises synthetic dyes from azo, anthraquinone, triphenylmethane, indigo, and other groups. Several azo dyes and their cleaved by-products have been discovered to impact human health. Various established techniques are commonly employed to remove the color from dye; however, they have inherent restrictions. Due to increased demand, there is a growing need to explore cost-effective alternative treatments, such as biological integrated systems. The utilization of laccase for the decolorization of dyes presents a possible technological solution to address the drawbacks associated with current approaches. These enzymes can chemically react with and break down diverse substances. Laccases have been verified for their capacity to break down synthetic dyes in wastewater, resulting in the degradation of less hazardous products than the original dyes. This study examines the advantages and disadvantages of different technologies used to remove color from dyes. It also discusses the degradation mechanisms of several synthetic dyes catalyzed by laccase and the impact of factors, such as temperature, pH, dye concentration, etc. Additionally, the most recent studies on decolorization utilizing laccase are reviewed.