Spectroscopic and Microscopic Identification of the Reaction Products and Intermediates During the Struvite (MgNH4PO4·6H2O) Formation from Magnesium Oxide (MgO) and Magnesium Carbonate (MgCO3) Microparticles.

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TitleSpectroscopic and Microscopic Identification of the Reaction Products and Intermediates During the Struvite (MgNH4PO4·6H2O) Formation from Magnesium Oxide (MgO) and Magnesium Carbonate (MgCO3) Microparticles.
Publication TypeJournal Article
Year of Publication2017
JournalACS Sustainable Chemistry & Engineering
Volume5
Start Page1567
Issue2
Pagination1567–1577
AuthorsKirinovic, Erica, Amanda N. Leichtfuss, Criztel Navizaga, Hanyu Zhang, Jennifer Schuttlefield-Christus, and Jonas Baltrusaitis
PublisherAmerican Chemical Society
ISBN Number2168-0485
Abstract

One of the key global challenges forthcoming will be maintaining a clean, useable natural water supply. Anthropogenic wastewater is an unavoidable result of population growth and societal development; therefore the treatment of wastewater is of the utmost importance. The mineral struvite (magnesium ammonium phosphate hexahydrate, MgNH4PO4·6H2O) is a cryst. material that occurs naturally in decompg. org. materials and been obsd. in sludge derived from the anaerobic digestion of animal farming liq. wastes and treated wastewater sludge. The accumulation of struvite on pipe walls and equipment surfaces has plagued the wastewater treatment industry though the formation of struvite prior to the treatment process could potentially provide a pathway for the sustainable recovery of the major nutrients nitrogen (N) and phosphorus (P). Current methods of nutrient removal from wastewater are mostly based on insol. Fe, Al and Ca salt formation followed by landfill disposal without returning them to the environment. Struvite is one of the most promising chem. platforms for recovering nutrients, which previously was done using expensive water-sol. magnesium salts. Our objectives were to examine the potential of low soly., naturally abundant magnesium inorg. materials (MgO and MgCO3) for the utilization of nutrient recovery from wastewater via time resolved ex situ XRD, ATR-FTIR and Raman analyses, and SEM measurements to identify reactive intermediates and use spectroscopic data for kinetics anal. Our data suggest that a common reactive intermediate between homo- and heterogeneously nucleated struvite exists that is due to the amorphous magnesium hydroxide structural units. The presence of low coordination O4C-H, O3C-H and O1C-H surface hydroxyl groups, assocd. with the surface steps, edges and kinks is proposed to enhance struvite formation and increase in their abundance and stabilization are suggested for the MgO and MgCO3 prepn. before the struvite recovery. Two different crystal morphologies (needle and rhomboidal) were obsd. for reactions with 600 and 4000 ppm of (NH4)2HPO4, which were proposed to form due to the kinetic control of the reaction at higher concns. Finally, Raman spectroscopy was used to measure the relative kinetics of struvite formation utilizing the relative populations of the magnesium carbonate or struvite, as obtained from the area under the 1125 and 950 cm-1 peaks providing a spectroscopic method to monitor reactive solid magnesium source conversion into struvite. [on SciFinder(R)]