Waste derivitized blue luminescent carbon quantum dots for selenite sensing in water

Herein, we report an environmental friendly, facile, and completely green synthetic method for producing carbon quantum dots (CQDs) from whey, a major dairy waste. The as-prepared monodispersed diameter CQDs exhibit blue luminescence with noteworthy quantum yield (~11.4%) and excitation dependent emission behaviour. Nuclear magnetic resonance (NMR) analysis reveals the presence of aromatized carbon peaks, leading to polymerized CQDs diameter architecture during whey pyrolysis. The X-ray and selected area electron diffraction patterns confirm their amorphous nature. Further, we demonstrate, these CQDs as an effective sensor probe for selective selenite monitoring in water upon functionalization with appropriate ligand. The functionalized GCQDs probe is shown to detect selenite with high sensitivity in 10-1000ppb detection range. Further it is selective for selenite over other relevant ions (such as Cu²⁺, As³⁺, As⁵⁺, Pb²⁺, Ni²⁺, Se⁶⁺, Cl^-, Br^-, NO₃^-, NO₂^- and F^-) and displays a sub-ppb detection limit at 1.1% relative standard deviation.