Desenvolvimento de nanofibras de Pectina/HPC/PEO e Gelatina/HPC/PEO pela técnica de eletrofiação para liberação controlada de nitrogênio

Abstract

The excessive use of nitrogen fertilizers, such as urea, presents significant challenges, including contamination of water bodies and volatilization, which reduces its agronomic efficiency. In this context, the development of controlled-release systems emerges as a promising alternative to optimize nitrogen availability and minimize environmental losses. The present study aimed to develop and characterize polymeric nanofibers based on pectin/HPC/PEO and gelatin/HPC/PEO incorporated with urea, targeting their application in controlled nutrient release systems. The selection of pectin and gelatin as polymeric matrices was based on their potential for the development of sustainable systems, aligned with the principles of the circular economy, through the use of biodegradable compounds derived from industrial by-products. The nanofibers were produced by electrospinning, using optimized polymer solutions to ensure process stability and the formation of continuous fibers. Morphological characterization by scanning electron microscopy (SEM) revealed that the addition of urea enabled the formation of a well-defined network of continuous nanofibers with diameters on the nanometric scale, ranging from 225 nm to 1,039 nm for pectin fibers, and between 209 and 440 nm for gelatin fibers. FTIR and EDS analyses confirmed the incorporation of urea and the existence of chemical interactions between the fertilizer and the polymer matrices. Thermal stability was investigated by TGA and DTG, indicating that the addition of urea reduced the Tonset​ of the matrices by 2.2 °C for pectin and 3.3 °C for gelatin, evidencing a plasticizing effect. However, the incorporation raised the degradation temperature of the urea to levels above 200 °C, compared to 130 °C for free urea. Controlled release assays in aqueous medium, monitored by UV-Vis spectroscopy, demonstrated that the nanostructured systems promoted the gradual release of the nutrient. The pectin matrix showed a more pronounced initial release, reaching 68% in the first hours, while the gelatin fibers exhibited a more sustained profile, releasing 43% in the same period. Thus, the developed materials demonstrated potential for application as controlled-release fertilizer systems, contributing to a more efficient use of nutrients in agriculture.