Complex Iron Phosphate Anions and Their Salts as Products of Chemisorption of Phosphates by Crystalline Iron Oxides

Abstract

Chemisorption of phosphate anions by crystalline iron oxides is confined to those sites of the sorbent surface where substitution of silicate (in hydrohematite) or hydroxo and aqua (in hydrogoethite) ligands by phosphate ions is possible. In these sites, new crystalline spherical entities were detected, which were able to pass into the liquid phase. The new formations were identified as ammonium salts of сomplex iron-phosphoric acids. Binding of ammonium cations from solution indicates that the primary phosphate chemisorption products are complex iron phosphate anions capable of being transferred to solution and destructuring iron oxides.