Synthesis and Characterization of a Novel Phosphorus Nanofertilizer Extracted from Agricultural Wastes.

Phosphorus (P) is a non-renewable resource and the main ingredient of fertilizers. Therefore novel methods of recovering P lost in the environment as well as in agricultural and food wastes are required not only to increase the lifespan of declining natural P reserves but also to decrease the pile-up of wastes and leaching of P in the environment which deteriorates water quality. In this study, we aimed to recover P from agricultural wastes and fabricate into a novel nanofertilizer: hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂]. Because the structure of hydroxyapatite nanoparticles (HANPs) is tunable, it allows varying the rate of P release according to plant needs and incorporation of micronutrients such as zinc and boron. Our preliminary results for pure chemical synthesis suggest that tuning of size of HANPs alters the dissolution rate and efficiency by up to 35%. Similarly, structural incorporation and surface association of zinc and boron into HANPs were found to be feasible. Effect of these elements on HANP dissolution and P release kinetics is still being investigated. Overall, our results show that the tuning of morphology and size of HANPs allows varying dissolution rate and thus optimizing the efficiency of P release.