Biomass-derived sensor for selective detection of Fe(III) ions in non-aqueous environments

Eco-friendly biomass-derived nanocarbons have gained considerable attention for detecting metallic pollutants, such as iron, in the environment. In addition, fluorescence probes are in high demand due to the growing need for iron detection in various organic solvents. Herein, we synthesize luminescent biomass-derived carbon nanoparticles (BMCNPs) from Kalanchoe pinnata plant leaves using a simple single-step solvothermal method. The synthesized BMCNPs emit red fluorescence in non-aqueous environments (organic solvents) and exhibit excellent fluorescence stability and solubility in both aqueous and non-aqueous media. The quenching of fluorescence emissions from BMCNPs in non-aqueous medium, facilitated by the addition of Fe(III) ions, demonstrates the ability of BMCNPs to serve as probes for detecting trace quantities of iron impurities. Experimental results confirm that the fluorescence from the BMCNPs is influenced by a ligand-to-metal charge transfer-assisted dynamic quenching mechanism. The proposed sensor is suitable for the real-time detection of iron in organic solvents, where iron contamination occurs due to the corrosion of iron metal. The fluorescence quantum yield of the probe is determined to be ∼11 %. The detection limit for Fe(III) in N,N-dimethylformamide using the synthesized probe is determined to be 1.9 µM. This study provides a platform for detecting Fe(III) ions in non-aqueous media. The proposed probe overcomes the limitation of Fe(III) ion-specific aqueous solubility, enabling the detection of Fe(III) ions in non-aqueous media due to the solubility and red emission specificity of BMCNPs in non-aqueous environments.