Feasibility of detection valence speciation of Cr(III) and Cr(VI) in environmental samples by spectrofluorimetric method with fluorescent carbon quantum dots.

Abstract

A simple and fast spectrofluorimetric method coupled with fluorescent carbon quantum dots have been developed for the detection and speciation chromium(VI) and chromium(III). The high fluorescence quantum yield (QY: 20.5%) carbon quantum dots (CQDs) were synthesized from natural kelp by hydrothermal method. The fluorescence of CQDs was effectively quenched by Cr(VI) due to inner filter effect (IFE) and the strong interactions between the functional groups on the CQDs surface and Cr(VI). Cr(III) species after oxidation of this species to Cr(VI) using KMnO4 as the oxidant were also detected by the proposed method. Under optimal conditions, the Cr(VI) could be detected with the range from 0.01 to 50 μM and a limit of detection 0.52 μM. And the synthesized CQDs were utilized as fluorescent probe to determinate Cr(III) and Cr(VI) in environmental water samples with satisfactory recoveries in the range of 94%-107%.