The efficient detection of Fe 3+ by sulfonamidated lignin composite carbon quantum dots

Fluorescent carbon quantum dots are a new type of nano‐fluorescent probe material, which overcomes some deficiencies of organic fluorescent materials and semiconductor quantum dots. In addition, they also have excellent optical properties, biocompatibility, and good application potential in environmental detection and other fields. To realize the special functions of carbon quantum dots, various functionalized composite carbon quantum dots have also been gradually developed. Lignin is a kind of natural polymer material rich in aromatic ring structure, which has abundant π electrons and a large number of easily functionalized active groups. Therefore, lignin is gradually used as a fluorescent probe material. In this article, sulfadiazine, p ‐aminobenzenesulfonic acid, ammonium sulfamate as the amination reagents were used to modify lignin, and then citric acid was used as raw material to prepare carbon quantum dots (CQDs), and finally sulfadiazine lignin composite carbon quantum dots (PSA‐L‐CQDs), sulfamic acid lignin composite carbon quantum dots (BSA‐L‐CQDs), and sulfamate amine lignin composite carbon quantum dots (ASA‐L‐CQD) were prepared. Their structure and fluorescence characteristics were analyzed. The selectivity and sensitivity of PSA‐L‐CQDs to metal ions were tested by fluorescence spectroscopy. The experimental results show that PSA‐L‐CQDs have good selectivity and high sensitivity to Fe 3+ . The detection limit of Fe 3+ was 29.5634 nmol/L. The composite carbon quantum dots have the advantages of low cost, simple manufacture, high selectivity, and high sensitivity.