Síntese e caracterização preliminar de um nanocomposto a base de resíduos da extração do suco dos frutos do cajueiro

Abstract

The large volume of residues generated by the cashew agroindustry, especially the peduncle bagasse rich in mineral elements and organic structures, highlights the need for strategies that promote its reuse and valorization. In this context, this study aimed to synthesize and preliminarily characterize a nanocomposite based on fibers from cashew fruits, targeting its potential application as an agricultural nanofertilizer. Carbon quantum dots were obtained through hydrothermal synthesis using cashew bagasse powder and citric acid as carbon sources, ethylenediamine as a passivating agent, and Hoagland nutrient solution as the reaction medium and as a source of micro- and macronutrients for plants. Material characterization involved mineralogical, gravimetric, and spectroscopic analyses, including ultraviolet–visible absorption spectroscopy, fluorescence spectroscopy, and Fourier transform infrared spectroscopy. The results confirmed the formation of carbon quantum dots with fluorescent behavior, exhibiting characteristic absorption and emission bands, as well as the presence of oxygenated and nitrogenated functional groups on the nanoparticle surface. The obtained quantum yield was 15.91, which is consistent with values reported for biomass-derived materials. The mineral composition of the residue revealed the presence of macro- and micronutrients relevant to plant development. Therefore, the synthesized nanocomposite demonstrated potential for agricultural application, combining nanostructured properties with the valorization of agroindustrial residues, in alignment with the principles of sustainability and green chemistry.