One-Step Green Synthesis of Water-Soluble Fluorescent Carbon Dots and Its Application in the Detection of Cu2

Saheed O Sanni; Theo H G Moundzounga; Ekemena O Oseghe; Nils H Haneklaus; Elvera L Viljoen; Hendrik G Brink

doi:10.3390/nano12060958

One-Step Green Synthesis of Water-Soluble Fluorescent Carbon Dots and Its Application in the Detection of Cu²

Nanomaterials (Basel). 2022 Mar 14;12(6):958. doi: 10.3390/nano12060958.

Authors

Saheed O Sanni^{1

2}, Theo H G Moundzounga², Ekemena O Oseghe³, Nils H Haneklaus^{4

5}, Elvera L Viljoen², Hendrik G Brink¹

Affiliations

¹ Department of Chemical Engineering, Faculty of Engineering, Built Environment and Information Technology, University of Pretoria, Pretoria 0028, South Africa.
² Biosorption and Wastewater Treatment Research Laboratory, Department of Chemistry, Faculty of Applied and Computer Sciences, Vaal University of Technology, Vanderbijlpark 1900, South Africa.
³ Institute for Nanotechnology and Water Sustainability, College of Science, Engineering and Technology, Florida Campus, University of South Africa, Johannesburg 1709, South Africa.
⁴ Institute of Chemical Technology, Freiberg University of Mining and Technology, Leipziger Straße 29, 09599 Freiberg, Germany.
⁵ Td Lab Sustainable Mineral Resources, University for Continuing Education Krems, Dr.-Karl-Dorrek-Straße 30, 3500 Krems an der Donau, Austria.

Abstract

Renewable biowaste-derived carbon dots have garnered immense interest owing to their exceptional optical, fluorescence, chemical, and environmentally friendly attributes, which have been exploited for the detection of metals, non-metals, and organics in the environment. In the present study, water-soluble fluorescent carbon dots (CDs) were synthesized via facile green microwave pyrolysis of pine-cone biomass as precursors, without any chemical additives. The synthesized fluorescent pine-cone carbon dots (PC-CDs) were spherical in shape with a bimodal particle-size distribution (average diameters of 15.2 nm and 42.1 nm) and a broad absorption band of between 280 and 350 nm, attributed to a π-π* and n-π* transition. The synthesized PC-CDs exhibited the highest fluorescent (FL) intensity at an excitation wavelength of 360 nm, with maximum emission of 430 nm. The synthesized PC-CDs were an excellent fluorescent probe for the selective detection of Cu²⁺ in aqueous solution, amidst the presence of other metal ions. The FL intensity of PC-CDs was exceptionally quenched in the presence of Cu²⁺ ions, with a low detection limit of 0.005 μg/mL; this was largely ascribed to Cu²⁺ ion binding interactions with the enriched surface functional groups on the PC-CDs. As-synthesized PC-CDs are an excellent, cost effective, and sensitive probe for detecting and monitoring Cu²⁺ metal ions in wastewater.

Keywords: Cu2+ ion detection; carbon dots; microwave pyrolysis; renewable biowaste.

Abstract

Grants and funding