One-pot hydrothermal green synthetic approach of fluorescent carbon dots as optical probes for 2-nitrophenol

Pogisego Dinake; Gothatamang N. Phokedi; Mbhatshi M. Keetile; Mmamiki A. Botlhomilwe; Mogomotsi Tlhako; Bokang Present; Janes Mokgadi; Rosemary Kelebemang

doi:10.17159/sajs.2023/13921

Authors

Pogisego Dinake Department of Chemical and Forensic Sciences, Botswana International University of Science and Technology, Palapye, Botswana https://orcid.org/0000-0003-2456-2043
Norma Phokedi Department of Chemical and Forensic Sciences, Botswana International University of Science and Technology, Palapye, Botswana https://orcid.org/0000-0002-3278-9988
Mbhatshi M. Keetile Department of Chemical and Forensic Sciences, Botswana International University of Science and Technology, Palapye, Botswana
Mmamiki A. Botlhomilwe Department of Chemical and Forensic Sciences, Botswana International University of Science and Technology, Palapye, Botswana
Mogomotsi Tlhako Department of Chemical and Forensic Sciences, Botswana International University of Science and Technology, Palapye, Botswana
Bokang Present Department of Physics and Astronomy, Botswana International University of Science and Technology, Palapye, Botswana
Janes Mokgadi 1.Department of Chemical and Forensic Sciences, Botswana International University of Science and Technology, Palapye, Botswana; 2.Chemical, Biological Nuclear and Radiological Weapons Management Authority, Ministry of Defence, Justice and Security, Gaborone, Botswana https://orcid.org/0000-0002-9970-5777
Rosemary Kelebemang 1.Department of Chemical and Forensic Sciences, Botswana International University of Science and Technology, Palapye, Botswana; 2.National Environmental Laboratory, Department of Waste Management and Pollution Control, Gaborone, Botswana https://orcid.org/0000-0002-5015-4951

DOI:

https://doi.org/10.17159/sajs.2023/13921

Keywords:

2-nitrophenol, fluorescence, carbon dots, green synthesis, biomass, Citrullus vulgaris

Abstract

The pursuit of a cost-effective and green synthetic approach to chemical sensors and their application in the sensing of toxic and harmful substances is a never-ending exercise for scientists and researchers. Preparation of fluorescent carbon dots (C-dots) from biomass using water as a solvent and a hydrothermal autoclave to provide the required synthesis temperature offers a cheap and environmentally friendly synthetic approach. Herein, we report a faster, less costly and ecofriendly hydrothermal synthetic approach of carbon dots from Citrullus vulgaris peels as a precursor. The as-prepared carbon dots exhibited hydroxyl, carbonyl and amide functional groups on the surface and an amorphous structure with a particle size distribution of 1.7–3.0 nm. Moreover, the carbon dots displayed intense blue emission fluorescence at 470 nm after excitation at 400 nm. The as-prepared carbon dots demonstrated effective application without further modification towards the selective and sensitive optical recognition of 2-nitrophenol used in the manufacture of explosives. A limit of detection of 2.28×10⁻⁷M was achieved, and no fluorescence quenching was observed in the presence of other nitroaromatic and benzene derivatives indicating excellent selectivity towards 2-nitrophenol. Finally, further studies are required to investigate the potential for the as-prepared carbon dots to monitor nitroaromatic pollutants in real environmental systems.

Significance:

Terrorism is an ever-increasing problem, and law enforcement agencies are continuously searching for and detecting explosives hidden in travel luggage, mail packages, vehicles and aircrafts using sophisticated equipment which are not available in developing countries such as Botswana.
This work unveils a facile and environmentally friendly approach towards the detection of 2-nitrophenol used in the manufacture of explosives by employing highly luminescent C-dots obtained from locally available agricultural waste.
The utilisation of agricultural waste can help advance a sustainable waste management programme and promote a circular economy.