Starch: pectin acidic sachets development for hydroxyapatite nanoparticles storage to improve phosphorus release

Abstract

The importance of fertilizers in boosting crop production has motivated the development of novel high-performance systems capable of improving the phosphorus release in the soil. For instance, methods capable of increasing the surface area of fertilizer particles and promoting the solubilization of low-solubility compounds, including phosphates, are highly pursued. This study was aimed at synthesizing hydroxyapatite nanoparticles and investigating their solubility in relation to crystallinity, size, and morphology for phosphorous fertilizer applications. To improve the phosphate ions release, the hydroxyapatite nanoparticles were storage in biodegradable sachets composed of thermoplastic starch/pectin blends with different polymer ratios. The results showed that the smallest and less crystalline hydroxyapatite nanoparticles presented the highest solubility. After storage in polymeric thermoplastic starch:pectin sachets, solubility for all samples was greatly improved, enhancing the phosphorus release due to pH decrease, independent on the nanoparticle size, shape, and crystallinity. The results highlight that the use of acidic sachets is a valuable approach for enhancing phosphorus and other macronutrients release from fertilizers with basic surface properties, aiming at increasing agricultural crop productivity.