Nitrogen-doped carbon quantum dots based on deep eutectic solvents precursors detect Cr6+ in environmental water

Hexavalent chromium is the main compound in industrial wastewater, which is highly toxic and seriously pollutes the environment and endangers human health. The excellent fluorescence performance of carbon quantum dots (CQDs) is widely used to detect heavy metal ions. However, the quantitatively structure of CQDs is different to control in the formation due to the uncertain-complex of biomass-based materials. In this work, nitrogen-rich CQDs (N-CQDs) based on 4-A-1,2,4-TZ and glycerol deep eutectic solvents (DESs) was prepared by one-step hydrothermal method. The prepared N-CQDs exhibited excellent fluorescence stability. The response of the N-CQDs to Cr 6+ was linear in the range of 5-100   μM and a detection limit of 0.7043   μM. The results show that N-CQDs can achieve the detection of Cr 6+ well. Satisfactory recovery of Cr 6+ was also obtained by measuring in the wastewater.