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

Retention of phosphates from aqueous solutions with in sol–gel-derived amorphous CaO–MgO–Al₂O₃–SiO₂ system as a model of blast furnace slag

Bruno Kostura, Radim Huczala, Michal Ritz, and Juraj Leško

VŠB-Technical University Ostrava, Ostrava-Poruba, Czech Republic

E-mail: bruno.kostura@vsb.cz

Abstract: The article proposes new possibilities for the estimation of the maximum phosphate retention capacities (PRC) in blast furnace slags using their modeling. The amorphous blast furnace slag model (BFS–SG) and slag samples along the joining of the CaO:SiO₂ = 1 and (CaO + MgO):SiO₂ = 1 of the CaO–MgO–Al₂O₃–SiO₂ phase diagram were prepared by the sol–gel method. The surface analysis of BFS–SG was performed and the results were compared with real BFS. Batch adsorption experiments were performed to evaluate the phosphate removal of slags. SEM analysis and Raman spectroscopy were used to identify phosphate adsorbed forms. Phosphate retention is realized by the surface reactions of hydration products resulting in a nanostructured Ca-hydroxyapatite. The acid–base properties of the model samples in the selected cross-sections were characterized by the values of the optical basicity. An excellent linear relation between the phosphorus retention capacity (PRC) and the optical basicity of the model samples was found, which allows an estimation of slag retention capacities and the forms of adsorbed phosphorus.

Keywords: Phosphate sorption ; Sol–gel method ; Blast furnace slag ; Optical basicity 

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-017-0289-2

Chemical Papers 72 (2) 401–408 (2018)