Circular valorization of non-hazardous laboratory agar waste into fluorescent carbon nanomaterials with photocatalytic dye degradation potential

The generation of non-hazardous laboratory waste is increasing worldwide, yet its potential as a feedstock for high-value nanomaterials remains largely unexplored. In this study, we demonstrate a novel waste-to-nanomaterial valorization strategy by converting decontaminated laboratory agar waste into fluorescent carbon nanomaterials (CNMs) through gasification, followed by ultrasonic dispersion and purification. Unlike conventional biomass-derived CNMs synthesized from agricultural or municipal waste, this approach utilizes an underexplored laboratory waste stream, thereby promoting circular resource recovery and sustainable waste management. Morphological and structural characterization confirmed the formation of predominantly spherical CNMs with an average particle size of approximately 100 nm, as revealed by scanning and transmission electron microscopy. The synthesized CNMs exhibited bright fluorescence under UV illumination and characteristic UV–Vis absorption peaks at 220 and 270 nm, corresponding to π–π* electronic transitions of sp²-hybridized carbon. Fourier transform infrared spectroscopy analysis identified oxygen-containing surface functional groups and aliphatic hydrocarbons, while X-ray diffraction confirmed a partially graphitic crystalline structure. The photocatalytic performance of the CNMs was evaluated against methylene blue (MB) and crystal violet (CV) dyes under natural sunlight, achieving approximately 47% and 50% degradation, respectively, within 80 min. The study establishes an innovative pathway for transforming non-hazardous laboratory waste into functional fluorescent CNMs with promising applications in wastewater treatment, while advancing principles of circular economy, resource recovery, and sustainable environmental remediation.