TITLE:
Effect of Copper (II) Ions on Quality of Struvite Produced in Continuous Reaction Crystallization Process at the Magnesium Ions Excess
AUTHORS:
Nina Hutnik, Boguslawa Wierzbowska, Krzysztof Piotrowski, Andrzej Matynia
KEYWORDS:
Struvite; Phosphate(V) Ions; Copper Ions; Continuous Reaction Crystallization; DT MSMPR Crystallizer; Crystal Size Distribution; Product Quality
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.3 No.4B,
October
25,
2013
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.