Formation of pure struvite at neutral pH by electrochemical deposition

Previously we showed that pure struvite could be recovered from wastewater at neutral pH. This omits the need for adding alkalinity to the process. However, at a neutral pH value the reaction is relatively slow making it practically not a good system from an engineering point of view. In this study, electrochemical deposition was evaluated as a means to improve the formation of pure struvite at a neutral pH value. An electrolytic cell with an inert Pt (or graphite) anode and a nickel cathode was set up for the experiment. The generation of OH− via electrochemical reduction of dissolved oxygen slightly increased the interfacial pH near the cathode, resulting in rapid formation of the precipitates. The structure, morphology, composition and thermal properties of the harvested precipitate were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), microscopic analysis, infrared (IR) spectra, energy-dispersive spectrometry (EDS), element analysis (EA) and thermo-gravimetric analysis (TGA). All the analyses support formation of pure struvite in the precipitate.