Synthesis of Photoluminiscent Carbon Dots from Rice for Metal Sensing and Dye Degradation

Abstract

Carbon dots (CDs), commonly known as carbon quantum dots (CQDs), constitute an innovative category of zero-dimensional photoluminescent nano carbons, generally measuring less than 20 nm in diameter. CDs exhibit high selectivity in the detection of metal ions, small molecules, biopolymers, and various food components. These nanoparticles offer significant advantages owing to their superior biocompatibility, robust photoluminescent characteristics, and eco-friendly attributes, rendering them widely used in sensors, fluorescent inks, bio-imaging, and drug delivery systems. Initial investigations of rice types indicated the existence of carbon dots (CDs), leading to the formulation of this study aimed at synthesizing and characterizing CDs obtained from rice, as well as examining their utility in metal ion detection and dye degradation. The rice sample was air-dried at ambient temperature for two days, pulverized into a powder, filtered, and the filtrate was centrifuged at 4000 rpm before to lyophilization to get solid CDs. UV-visible spectroscopy was utilized to verify the effective production of the carbon dots. The manufactured CDs were examined using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction Analysis (XRD), and Photoluminescence (PL) Spectroscopy. These CDs were then applied in metal ion sensing and dye degradation, with the study primarily utilizing UV-vis and Photoluminescence spectroscopic techniques. The limits of detection and quantification for Fe3+ were 8.57 µM and 28.57 µM, respectively, while for Mn7+, they were 7.2 µM and 24.34 µM. The degradation percentages of Congo red, methyl orange, and methylene blue dyes were 80%, 95%, and 80%, respectively. Thus, the study successfully demonstrated the effective use of rice-derived CDs for metal ion detection and dye degradation.