For this purpose, different compositions (0–8% v/v with an interval of 2, and 10–100% v/v with an interval of 10) of 1,4-dioxane–water mixtures were prepared, and 0.05 mg mL−1 of PD-CNDs was added to 10 mL of each of these mixtures and sonicated for 10 min. The fluorescence spectra of these samples were recorded.