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An electrochemical study of ammonium dihydrogen phosphate on Mg and Mg alloy electrodes

Harvard Dataverse (Africa Rice Center, Bioversity International, CCAFS, CIAT, IFPRI, IRRI and WorldFish)

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Title An electrochemical study of ammonium dihydrogen phosphate on Mg and Mg alloy electrodes
 
Identifier https://doi.org/10.7910/DVN/WI7R6X
 
Creator Kekedy-Nagy, Laszlo
Abolhassani, Mojtaba
Greenlee, Lauren
Pollet, Bruno
 
Publisher Harvard Dataverse
 
Description In this work, the electrochemistry of ammonium dihydrogen phosphate in aqueous solution on Mg and Mg AZ31 alloy (Al 3 wt%, Zn 1 wt%, balanced Mg) electrodes was studied using electrochemical characterization similar to electro-agglomeration and physical characterization to shed some light on the electrochemical mechanism of struvite formation as phosphate precipitation in waste. It was found that the Mg AZ31 alloy exhibited higher corrosion current densities (jcorr), therefore, higher Mg2+ dissolution rates compared to pure Mg. This finding was confirmed by ion chromatography (IC) analysis, in which the presence of Mg2+ was due to the oxidation of the Mg metal, and the higher Mg2+ concentration for the Mg AZ31 alloy 62.7 ppm vs. 57.5 ppm for pure Mg was in good agreement with the higher obtained corrosion rates (vcorr). Results also showed a phosphorus removal efficiency (PRem) of 16.8% with ~53 mL H2 production for pure Mg anode and 17.2% with ~61 mL H2 production for Mg AZ31 alloy. The precipitates formed on the Mg based discs were studied and analyzed by SEM, XRD, XPS, EDX while the physical characterizations of the obtained films corresponded to struvite (magnesium ammonium phosphate hexahydrate - MgNH4PO4*6H2O). It was found that (i) the thickness of the films was influenced by the applied scan rates, which also had a significant impact on the morphology, and (ii) hydrogen bubble formation influenced the precipitates whereby the film thicknesses were negatively impacted.
 
Subject Chemistry
 
Contributor Kekedy-Nagy, Laszlo