Microwave assisted green synthesis of carbon dots from sweet flag (Acorus calamus) for fluorescent sensing of 4-nitrophenol

Abstract

In this piece of work, a simple and cost-effective fluorescence sensor for the detection of 4-nitrophenol (4-NP) was developed from natural resource, sweet flag (Acorus calamus) through greener route by the use of microwave energy. 4-NP is identified as a potential water pollutant by EPA which can exert several hazardous effect in humans and other aquatic organisms and hence lower level detection of 4-NP is highly demanding. The as obtained carbon dots with excitation dependent fluorescence behaviour, designated as SFCDs, produced a noticeable quenching in fluorescence on interacting with 4-NP. Therefore, a simple and time-saving fluorescence sensing for the detection of 4-NP was developed. The observed turn-off in fluorescence of SFCDs with 4-NP was investigated through different experiments and finally accredited to a combination of both static quenching and inner filter effect (IFE). The proposed probe selectively detect the 4-NP with LOD of 0.207 µM and linear range of 0–14.28 µM, the detection limit was found to be lower than allowed concentration of this pollutant in drinking water. Furthermore, the same method has been practically applied for detecting 4-NP in natural water resources with good level of recovery percentages. As a whole, the developed method gives value addition to the sweet flag for the first time by its direct materialization through a completely greener route without using any hazardous chemicals. The good level of precision and accuracy with detection limits in micromolar range are promising to use the system as a fluoroprobe for detecting 4-NP, a primary pollutant found in natural water resources.