Boron and nitrogen co-doped bright yellow fluorescent carbon dots as real-time selective detection of phthalic acid plasticizer in aqueous medium

Abstract

Excessive usage and discharge of phthalic acid in the environment affect endocrine system of living beings via bioaccumulation in food chain. In this paper, boron and nitrogen co-doped yellow fluorescent carbon dots (B, N-C-dots) have been designed for the rapid recognition of plasticizer phthalic acid. These C-dots were prepared by carbonization of 4-bromo-1,2-diaminobenzene and boric acid mixture. The bright fluorescence (PLQY = 26.4 %) of C-dots showed a significant Stokes shift of 145 nm under 430 nm excitation wavelength. These B, N-C-dots selectively detect phthalic acid in aqueous solution instantaneously and experienced a maximum 95 % fluorescence quenching immediately upon the treatment with phthalic acid with a limit of detection of 91.12 nM. It has been proved that the combined effect of strong intermolecular hydrogen bonding, chemical conjugation, and non-fluorescent ground state complex formation between the probe and analyte led to fluorescence quenching of the C-dots. Static quenching has been confirmed from changes in B, N-C-dots UV–vis absorbance spectroscopy and non-changes in fluorescence lifetime after adding phthalic acid. Furthermore, these B, N-C-dots were successfully applied to recover the analyte in real water samples and showed an average recovery rate of 96.4–102 % with a good relative standard deviation from spiked samples. This study provides selective recognition ability in the field of environmental monitoring and remediation.