Green synthesis and characterization of nitrogen-doped carbon dots for enhanced photocatalytic tylosin degradation in soil

This study reports one-pot green synthesizing and characterizing nitrogen-doped carbon dots (N-CDs) with green-light-emitting fluorescent features. For the said purpose, citrus-containing pulp-free juice was extracted from the lemon (as a green carbon precursor) and subjected to a carbonization process in the presence of urea as a doping agent. In addition, the characteristic-dependent factors, i.e., carbonization temperature (i.e., 160 °C, 210 °C, and 260 °C) and reaction periods (i.e., 2 and 4 h), were also varied to investigate their influence on the synthesis and characteristic attributes of N-CDs. Under UV light at 365 nm, the fabricated N-CDs exhibited strong green light emission up to different extents from light green to bright green range. Overall, the green-light-emitting fluorescent potential of all prepared N-CDs was found to be temperature and time-dependent. The UV-Vis spectral profile revealed characteristic absorption peaks of 288, 333, and 407 nm, confirming the formation of N-CDs. The FTIR profile revealed the functional group entities with evident peaks in 3345 cm^-1, 2120 cm^-1, and 1636 cm^-1 regions corresponding to O-H, C=C, and NO₂. The surface topology and size distribution characteristics were studied through SEM, TEM, and Image J analysis. The results showed uniformly dispersed particles with a minimum average diameter of 6.63 ± 0.07 nm. The EDS/EDX analysis results validated the elemental composition of the samples, distinctly indicating that carbon predominates as the major element across all samples. The catalytic breakdown potential of N-CDs was tested against Tylosin removal from contaminated soil samples (identified and quantified through LC-MS/MS analysis). This evaluation revealed a notable 39.2% maximum removal efficacy, positioning them as exceptional candidates for catalyzing environmental remediation and protection.