Effect of Copper (II) Ions on Quality of Struvite Produced in Continuous Reaction Crystallization Process at the Magnesium Ions Excess

Nina Hutnik, Boguslawa Wierzbowska, Krzysztof Piotrowski, Andrzej Matynia

Silesian University of Technology, Department of Chemical & Process Engineering, M. Strzody, Gliwice, Poland.
Wroclaw University of Technology, Faculty of Chemistry, Wybrzeze Wyspianskiego, Wroclaw, Poland.

DOI: 10.4236/aces.2013.34B001                

Abstract

The research results concerning continuous removal of phosphate (V) ions from solutions containing 1.0 or 0.20 mass % of phosphate (V) ions and 0.2 or 0.5 mg/kg of copper (II) ions using magnesium and ammonium ions addition are presented. Continuous reaction crystallization of struvite MgNH₄PO₄ × 6H₂O ran both under stoichiometric conditions and at 20% excess of magnesium ions (pH 9, t 900 s). It was concluded, that presence of copper (II) ions in a process system influenced product quality moderately advantageously. Mean size of struvite crystals enlarged by ca. 6% only. Lower concentration of phosphate (V) ions and excess of magnesium ions caused, that products of ca. 9% - 13% larger crystal mean size (up to ca.40mm) were removed from the crystallizer. Presence of struvite crystals and copper (II) hydroxide were detected analytically in the products (Cu in a product varied from 6 to 90 mg/kg). Presence of copper (II) ions favored crystallization of struvite in the form of tubular crystals.

Keywords

Struvite; Phosphate(V) Ions; Copper Ions; Continuous Reaction Crystallization; DT MSMPR Crystallizer; Crystal Size Distribution; Product Quality

Conflicts of Interest

The authors declare no conflicts of interest.

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