Sensitivity fluorescent switching sensor for Cr (VI) and ascorbic acid detection based on orange peels-derived carbon dots modified with EDTA

•Different kinds of orange peels were applied to synthesize CDs.•Relationship between QYs and amounts of volatile oils were investigated.•Orange peels based CDs were modified with EDTA for the first time.•The CDs@EDTA was applied to the sensitive detection of Cr(VI).•CDs@EDTA/Cr(VI) system was further applied for AA detection. Orange peels were applied as precursors to synthesize carbon dots (CDs) via a one-step green hydrothermal method. The relationship between quantum yield and volatile oils in 14 different varieties of orange peels were investigated. The CDs showed strong blue fluorescence and were further modified with EDTA. Compared with the CDs, the CDs@EDTA exhibited higher sensitivity for Cr(VI) detection with a LOD of 10 nM. The CDs@EDTA was proved to be an effective fluorescent sensor element for Cr(VI) detection in water samples with recoveries ranged from 92.09% to 104.87% (RSD