Processing of starch composite with CuO nanoparticles for fungicide application and controlled release of Cu 2+ ions

Abstract

Due to the growing demand for mineral fertilizers as agricultural inputs, scientific and technological development in this area is necessary in order to supply the agricultural market demand for higher production and lower costs. In this context, the present research project aims to develop a biodegradable starch-based system that promotes a slow/prolonged release of copper ions, aiming to use as a fertilizer. Copper is an important mineral micronutrient present in several plant metabolic activities, in addition, the cooper coming from CuO nanoparticles can act as fungicide and bactericide. In contrast to the increased solubility expected for nanoparticulate micronutrients, one of the great adversities in the application is the losses caused by leaching and aerial dispersion, causing crop deficiency. In order to control the Cu2+ release from CuO and improve this ion availability, films based on starch, a low cost biopolymer obtained from natural sources and agricultural residues will be developed. However, the initial characteristics of starch films are subject to changes due to a degenerative effect, considering the hygroscopicity and ease of microorganism proliferation in the film. For this reason, besides the availability of Cu2+ ions as micronutrients to the soil, the CuO nanoparticles will act as a reinforcement material to the polymer matrix, in order to minimize the degradation and prolong shelf life through the synergistic effect between the barrier and antimicrobial properties that are expected for this compound. Thus, this project aims to find the best conditions for obtaining starch composite films incorporating CuO nanoparticles of controlled purity, size and shape, synthesized by coprecipitation. Once these conditions are found, aiming to reduce the processing cost and making it available for future scheduling, the commercial CuO will be evaluated for this application. Particle size control of commercial CuO will be carried out by high energy milling in order to correlate particle size with solubility, barrier property and antimicrobial response between the laboratory synthesized CuO and the commercial one. Thus, it is expected that once this proposal is completed, this material may be an alternative to minimize the leaching effects and to provide the prolonged release of copper ions, aiming to apply this material as a soil fertilizer.