BORON-DOPED CARBON QUANTUM DOTS FOR EVALUATION OF INTERACTION WITH METALS IN SOIL SAMPLES.

• Grant number: 25/13529-7
• Support Opportunities: Regular Research Grants
• Start date: October 01, 2025
• End date: September 30, 2026
• Field of knowledge: Physical Sciences and Mathematics - Chemistry
• Principal Investigator: Márcia Cristina Bisinoti
• Grantee: Márcia Cristina Bisinoti
• Host Institution: Instituto de Biociências, Letras e Ciências Exatas (IBILCE). Universidade Estadual Paulista (UNESP). Campus de São José do Rio Preto. São José do Rio Preto , SP, Brazil
• Associated research grant: 24/17456-1 - Development of hydrochar and magnetic char for carbon sequestration, nutrients release and environmental pollutants remove, AP.R

Abstract

This project proposes the synthesis of boron-doped carbon quantum dots (CQDs) from the hydrothermal carbonization of sugarcane bagasse, primarily aiming to understand their interaction with various metal ions that may be present in the soil for remediation purposes, as well as for nutrient availability. Different synthesis conditions will be evaluated to determine the factors that most contribute to a higher quantum yield, by varying the carbonization temperature and time, and the boric acid concentration. The hydrothermal synthesis will be conducted using a stainless steel reactor containing sugarcane bagasse and water in a 1:20 (w/v) ratio with the addition of boric acid (H¿BO¿), following a 2³+1 design of experiments (DoE). This design consists of varying the temperature (140-240 ºC), time (8-24 h), and amount of H¿BO¿ (10-30%), with a triplicate at the central point (190 ºC for 16 h with 20% of H¿BO¿). The quantum dots with the best yield will be characterized by transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and fluorescence analysis. For the material with the highest quantum yield, its interaction with several metal cations (e.g., Pb(II), Cr(VI), Cu(II), among others) will be evaluated. In these experiments, the quantum dots will be kept at a fixed concentration and titrated to a final concentration of 50 µmol L¿¹ of each cation, followed by stirring at 100 rpm for 10 minutes. After this period, the fluorescence will be measured for each condition. For the cation that elicits the best response, a constant concentration of quantum dots will be titrated with increasing concentrations of the cation standard, and the fluorescence suppression will be monitored. The Stern-Volmer model will be used to determine the interaction behavior (Raja et al., 2023).Furthermore, after these studies, the samples will be lyophilized for FTIR readings, followed by two-dimensional correlation spectroscopy (2D-COS) analysis, to identify the functional groups responsible for the interaction between the quantum dot and the cation (Santos et al., 2021). Batch studies in the presence of weathered soils, such as argisols, will also be conducted. The composition of the quantum dots and the properties of the samples will also be investigated using various analytical instruments and equipment. (AU)