Synthesis of stable suspension zinc-phosphate micro/nanoparticles under acid and alkaline conditions

Abstract In the present work, we synthesized zinc-phosphate particles (Zn 3 (PO 4 ) 2 ) of micro- and nanometric sizes (ZnPMCPs y ZnPNPs) through chemical reduction under acidic and alkaline conditions, aiming to obtain stable colloidal solutions either in the reaction medium or through particle suspension. In acidic media, the addition of hydrochloric acid (HCl), citric acid (AC), or ascorbic acid (AA) led to the formation of spherical structures with zeta potential superior to + 100 mV. Conversely, the use of ammonium hydroxide (NH 4 OH) in alkaline conditions resulted in oval flat-shaped structures with zeta potential below − 53.9 mV, with a tendency toward agglomeration before suspension. Among the tested media, HCl proved to be the most effective for nanoparticle suspension, enabling the production of particles with average hydrodynamic diameters below 25 nm and exhibiting high colloidal stability based on their zeta potential absolute values. These findings demonstrate a simple, reproducible method for producing micro/nanoparticles with excellent colloidal stability, which can be recovered post-suspension without loss of stability. The synthesized particles have promising potential for applications in biomedical engineering and anticorrosive coatings. Graphical abstract