Green Synthesis of Fluorescent Carbon Dots as a Sustainable Catalyst for Thymol Blue Dye Degradation

Industrial discharge of synthetic dyes, particularly thymol blue (TB), poses a major environmental concern due to their chemical nature and toxicity toward aquatic life and human health. TB, a sulfonephthalein dye extensively used in laboratory and textile sectors, demonstrates high resistance to conventional treatment methods. Carbon dots (CDs), synthesized through a green, biomass-derived route, exhibit dual fluorescence behavior with prominent green (λ_max 521 nm) and orange emissions (λ_max 665 nm), and have emerged as efficient catalysts for environmental remediation. Their ability to generate reactive oxygen species (ROS) enables the degradation of persistent organic pollutants. Herein, green-synthesized CDs from paddy straw are reported to demonstrate rapid catalytic degradation of TB in under 1 min. The process is driven by the generation of ROS, which effectively cleaves the TB molecules into less harmful byproducts. These results demonstrate that biomass-derived CDs provide a sustainable, cost-effective alternative to traditional wastewater treatments, significantly mitigating the environmental concern of dye pollution. Moreover, the green synthesis strategy minimizes hazardous byproduct formation, advancing sustainable chemistry principles and promoting the circular economy through the utilization of biomass waste into functional nanomaterials.