A mechanochemical preparation, properties and kinetic study of kaolin–N, P fertilizers for agricultural applications**

Abstract

Solvent-free ball milling was used to activate kaolin, a trioctahedral clay material, with diammonium phosphate[(NH4)2HPO4] to serve as a fast-acting phosphorus and nitrogen releasing fertilizer. Different tests on a mixture of 3:1 weight ratio of kaolin: (NH4)2HPO4 were performed to analyze the level of incorporation of (NH4)2HPO4 in the kaolin and the degree of liberation of NH4+{\rm{NH}}_4^ + and PO43−{\rm{PO}}_4^{3 - } ions into solution. The experimental mill speeds were varied from 200 to 700 rpm rotational rates for a fixed period of 2 hours. Several milling periods of 1, 2, and 3 h. were studied at the fixed milling speed of 600 rpm. To explain the properties of activated materials and to understand the purpose behind the simpler disintegration of phosphorus, several analytical methods such as FT-IR, TGA-DTG and Ion chromatography (IC) were used. The proposed procedure was environmentally friendly, and it helped to maintain a balanced supply of nitrogen and phosphorus fertilizer for agriculture's long-term development by offsetting some of the existing high-cost chemical fertilizer. The results demonstrated that the mechanochemical reaction could yield an intercalated form of kaolin that is a transmitter of N and P sources in fertilizers.

Keywords

• solid-state
• high energy ball milling
• sustainable slow-release fertilizers
• diammonium phosphate