Preparation of Fluorescent Carbon Dots and Application for the Detection of Trace Cr(Ⅵ)
This study focused on a kind of yellow fluorescent carbon dots(Y-CDs)prepared by chemical oxida-tion with acetaldehyde and sodium hydroxide as raw materials under normal temperature and pressure.Y-CDs were characterized by high-resolution transmission electron microscopy,infrared spectroscopy,X-ray photoelec-tron spectroscopy,ultraviolet spectroscopy and fluorescence spectroscopy.The results showed that the average particle size of the prepared Y-CDs was about 6 nm,the fluorescence quantum yield was 16.3%,the optimal ex-citation wavelength was 360 nm,and the maximum emission wavelength was 513 nm.It was found that Cr(Ⅵ)had a significant fluorescence quenching effect on Y-CDs,which was mainly caused by the inner filter effect and resonance energy transfer of fluorescence.Based on this mechanism,a method for the detection of trace Cr(Ⅵ)was established.When concentration of Cr(Ⅵ)was in the range of 0-240 mol/L,the fluorescence intensity of Y-CDs had a good linear relationship with Cr(Ⅵ)concentration(R2=0.990 3),and the detection limit(LOD)was 1.67 μmol/L.The method can be applied to the detection of trace Cr(Ⅵ),with the added standard recovery rate of 97.05%-104.0%(RSD≤4.38%,n=3).
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