Eco-friendly nanofertilizers from biogenic hydroxyapatite

• Grant number: 23/09890-0
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: August 01, 2024
• End date: July 31, 2025
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Marcelo Eduardo Alves
• Grantee: Felipe Hipólito dos Santos
• Supervisor: Deb Jaisi
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Institution abroad: University of Delaware (UD), United States
• Associated to the scholarship: 22/11235-8 - Thermo- and mechanochemical treatments to increase the phytoavailability of phosphorus in cattle bones, BP.DR

Abstract

Agriculture on highly weathered Brazilian soils faces significant challenges due to the natural scarcity of available nutrients and the high capacity for phosphorus (P) immobilization. As agriculture expands in Brazil, the demand for P fertilizers has increased, making them highly valued in the market of agricultural inputs. The use of animal bones as source of secondary P constitutes a promising alternative to the geogenic minerals, given the upward generation of this residue in the national territory. However, in terms of processing and efficiency of use, the mere grinding of animal bones for application as fertilizer is limited due to sanitary concerns and the low efficiency of nutrient recovery. Calcination and high-energy milling of ashes have been successfully employed to produce nanostructured hydroxyapatite from cattle bones, which has shown promising results as P fertilizer, particularly for crops grown in acidic soils. However, these methods involve high operational costs. An alternative, cost-effective approach is the alkaline hydrolysis of bones, which yields comparable results to calcination and high-energy milling. In this proposal, alkaline hydrolysis is proposed as a step forward regarding the thermo-mechanical techniques presented in the regular FAPESP grant (Process 2022/11235-8) to isolate and recover hydroxyapatite nanoparticles. In addition, P extraction from biogenic and synthetic nanomaterials using a 1 mM citrate solution buffered at pH 4.8 followed by ultrafiltration will be investigated for its effectiveness as an indicator of plant availability of this nutrient.