Optimized preparation of nitrogen-doped carbon dots by response surface methodology and application in Cd²⁺ detection

Abstract

The technical parameters of synthesizing N-doped carbon quantum dots (N-CQDs) from citric acid and tris(hydroxymethyl)aminomethane (Tris) were optimized using a Box-Behnken model of response surface methodology. Statistical analysis showed the quantum yield was significantly affected by reaction time and Tris weight. The optimal synthesis conditions were reaction temperature at 170 °C, reaction time of 4.50 h and Tris weight of 0.70 g, with the quantum yield up to 82.4%. The N-CQDs probe was further applied for Cd²⁺ detection. The fluorescence intensity and Cd²⁺ concentration were linearly related in the range of 20-300 µg·L⁻¹ with a relation coefficient of 0.9956 and a detection limit of 20.69 µg·L⁻¹.

Keywords:

• N-CQDs
• High quantum yield
• Response surface methodology
• Optimized design
• Cd2+ detection

Additional information

Funding

This research was funded by the Dr. Start-up Foundation of Chaohu University (KYQD-201602), and School-level Scientific Research Projects of Chaohu University (XLY-201607, XLZ-201805).