ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Influence of the synthesis pathway of monoammonium phosphate fertilizer on the physicochemical properties of granules: focus on dust emission

Abderrahim Benzaouia, Hamza Belbsir, Said Kounbach, Said Laassiri, Rachid Boulif, Abdelghani Laamaoui, and Rachid Bnhida

Chemical and Biochemical Sciences. Green Process Engineering (CBS.GPE), Mohammed VI Polytechnic University (UM6P), Ben Guerir, Morocco

E-mail: Abderrahim.BENZAOUIA@um6p.ma

Received: 3 April 2025  Accepted: 19 July 2025

Abstract:

This study focuses on the synthesis routes of monoammonium phosphate (MAP), a fertilizer widely used in modern agriculture and known for its high phosphorus and nitrogen content. MAP is produced through the controlled mixing of ammonia and industrial phosphoric acid, culminating in an equimolar ratio in the granulator. This acid–base neutralization reaction can follow two distinct pathways based on the titration mode, which are forward and back titration. The primary objective of this research is to conduct detailed physicochemical studies of the MAP product in order to assess and understand the influence of each synthesis pathway on the physicochemical properties of the granules with a focus on dust emission. Various techniques have been used to characterize the slurry and granulated MAP, such as SEM, NMR, TGA, XRD, dust and hardness measurements, as well as other chemical analyses. XRD, FTIR, and NMR analyses confirmed that both the back titration and the forward titration allowed to synthesis MAP at the molecular level. However, these pathways showed two effects: the first, on the morphology, texture, hardness of the MAP particles and dust generation, and the second, on the crystallization form of the impurities (Al, Fe) NH₄H₂(PO₄)₂·0.5H₂O and (Al, Fe) NH₄HF₂PO₄, which affect the physical behavior of MAP particles.

Keywords: Monoammonium phosphate; Fertilizer; Forward titration; Back titration; Characterization; Dusting

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-025-04269-0

Chemical Papers 79 (11) 7537–7554 (2025)