Dyes and their toxicity: removal from wastewater using carbon dots/metal oxides as hybrid materials: a review

Abstract

Clean water and a hygienic living environment are fundamental necessities for a healthy life. However, both domestic and industrial carcinogenic dyes have significantly reduced drinkable water sources and caused severe ecological problems. This situation seriously threatens human civilization, sustainable global development, and the marine ecosystem. Researchers have focused on advanced techniques to remove or degrade toxic dyes more effectively than conventional wastewater treatment methods to address these challenges. This study explores an efficient, quick, and cost-effective approach for degrading and removing toxic dyes from wastewater using carbon dots (CDs) and metal oxides (MOs). The hybrid CD/MO system offers several advantages over traditional methods, including enhanced optical properties, improved catalytic efficiency, structural modification, enhanced adsorption capacity, superior charge transfer, and increased chemical stability. This review provides a detailed introduction to dyes and their classifications, as well as the environmental and health impacts of dyes. It then describes various dye removal methods and, for the first time, explores the application of hybrid carbon dot/metal oxide systems for removing toxic dyes from wastewater. Additionally, we discuss current challenges and future perspectives in dye removal, aiming to provide an overview of recent advancements in wastewater treatment, highlight the associated challenges, and suggest potential future directions.