Mechanochemical Synthesis of Zinc Borate for Use as a Dual-Release B Fertilizer

• Published in: ACS sustainable chemistry & engineering 2021-11, Vol.9 (47), p.15995-16004
• Main Authors: Zheng, Bo, Kabiri, Shervin, Andelkovic, Ivan B, Degryse, Fien, da Silva, Rodrigo, Baird, Roslyn, Self, Peter, McLaughlin, Mike John
• Format: Article
• Language: English
• ISSN: 2168-0485; 2168-0485
• DOI: 10.1021/acssuschemeng.1c07111

This study investigated a mechanochemical method to synthesize a slow-release micronutrient fertilizer containing zinc (Zn) and boron (B). Two reactants ZnO and B2O3 were milled in a ball mill for 4 or 8 h with small quantities of water as part of liquid-assisted grinding, with or without a water-assisted reaction (WAR). The products were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Low-solubility zinc borate (2ZnO·3B2O3·7H2O), with an octahedral crystal morphology, was successfully synthesized by ball milling and WAR. A column dissolution study showed that the products made by 8 h milling followed by 72 h of WAR exhibited a slow and dual-release pattern of B release, with 26% of the total B released after a 72 h dissolution period. Products made without milling or without WAR showed much faster B release. The proposed synthesis route is a sustainable manufacturing process that is energy efficient and does not generate any noxious effluents, producing a material containing two important micronutrients with a slow release rate.