Eco‐friendly synthesis of carbon dots from waste banana peel for chromium( VI ) remediation: Structural, kinetics, and adsorption isotherm investigations

Hexavalent chromium (Cr(VI)) is a highly toxic and persistent environmental contaminant, highlighting the need for sustainable remediation strategies. In this study, we report the eco‐friendly synthesis of carbon dots (CDs) from waste banana peels via a straightforward hydrothermal method. FESEM analysis revealed particle aggregates of approximately 32 nm, while photoluminescence measurements confirmed excitation‐dependent emission arising from quantum‐confined sp 2 domains (<10 nm), supporting their classification as CDs. Structural characterization indicated partially ordered graphitic domains enriched with oxygen‐containing functional groups, conferring excellent aqueous dispersibility and multiple active sites for Cr(VI) adsorption. Batch adsorption experiments demonstrated effective Cr(VI) removal. Kinetic analysis suggested that adsorption is predominantly governed by surface interactions, whereas thermodynamic parameters indicated a spontaneous, entropy‐driven, and endothermic process. Equilibrium data were best described by the Langmuir model, yielding a maximum monolayer adsorption capacity of 25.51 mg/g. Post‐adsorption FESEM and EDS analyses confirmed Cr(VI) binding and surface modification of the CDs. Overall, these findings demonstrate that biomass‐derived CDs serve as cost‐effective, environmentally benign nano‐adsorbents, advancing sustainable nanotechnology and heavy metal remediation.