A 31P NMR and TG/DSC-FTIR investigation of the influence of initial pH on phosphorus recovery as struvite

Ning Ma; Ashaki A. Rouff; Brian L. Phillips

doi:10.1021/sc4004746

A ³¹P NMR and TG/DSC-FTIR investigation of the influence of initial pH on phosphorus recovery as struvite

Ning Ma, Ashaki A. Rouff, Brian L. Phillips

Research output: Contribution to journal › Article › peer-review

43 Scopus citations

Abstract

Phosphorus can be reclaimed from nutrient-rich sources as the mineral struvite (MgNH₄PO₄·6H₂O) for reuse as fertilizer. This study determines the impact of initial pH (pH_i) from 8 to 11 on the fraction of precipitated struvite from a MgCl ₂-(NH₄)₂HPO₄-NaCl-H₂O system. The rate of P removal from solution increases with pH_i and maximizes at pH_i 10. Scanning electron microscopy (SEM) of recovered precipitates shows changes in morphology and decreasing particle size with increasing pH_i. ³¹P nuclear magnetic resonance spectroscopy (NMR) confirms that struvite constitutes 96-99% of the phosphate at pH_i 8-10, with newberyite (MgHPO₄·3H₂O) as a minor crystalline phase. At pH_i 11, 60% of the solid is struvite, with 22% of the phosphate contained in an amorphous phase and 18% as sodium phosphate. Thermogravimetric analysis (TG) reveals a correlation in the mass loss from the solids with the percentage of struvite detected. Coupling Fourier transform infrared spectroscopy (FT-IR) with TG indicates that the molar concentration of evolved H₂O(g) and NH₃(g) is influenced by the adsorption of NH₄⁺(aq) at pH_i 8-10 and by the low percentage of struvite at pH_i 11. Overall, results indicate that both the amount of P recovered and the fraction of struvite are optimized at pH_i 10. These findings can be used as a starting point in the selection of a suitable pH_i for struvite recovery from nutrient-rich wastes.

Original language	English (US)
Pages (from-to)	816-822
Number of pages	7
Journal	ACS Sustainable Chemistry and Engineering
Volume	2
Issue number	4
DOIs	https://doi.org/10.1021/sc4004746
State	Published - Apr 7 2014
Externally published	Yes

All Science Journal Classification (ASJC) codes

Chemistry(all)
Environmental Chemistry
Chemical Engineering(all)
Renewable Energy, Sustainability and the Environment

Keywords

P NMR
P fertilizer
P recovery
P sustainability
Simultaneous thermal analysis
Struvite
Wastewater

Access to Document

10.1021/sc4004746

Cite this

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title = "A 31P NMR and TG/DSC-FTIR investigation of the influence of initial pH on phosphorus recovery as struvite",

abstract = "Phosphorus can be reclaimed from nutrient-rich sources as the mineral struvite (MgNH4PO4·6H2O) for reuse as fertilizer. This study determines the impact of initial pH (pHi) from 8 to 11 on the fraction of precipitated struvite from a MgCl 2-(NH4)2HPO4-NaCl-H2O system. The rate of P removal from solution increases with pHi and maximizes at pHi 10. Scanning electron microscopy (SEM) of recovered precipitates shows changes in morphology and decreasing particle size with increasing pHi. 31P nuclear magnetic resonance spectroscopy (NMR) confirms that struvite constitutes 96-99% of the phosphate at pHi 8-10, with newberyite (MgHPO4·3H2O) as a minor crystalline phase. At pHi 11, 60% of the solid is struvite, with 22% of the phosphate contained in an amorphous phase and 18% as sodium phosphate. Thermogravimetric analysis (TG) reveals a correlation in the mass loss from the solids with the percentage of struvite detected. Coupling Fourier transform infrared spectroscopy (FT-IR) with TG indicates that the molar concentration of evolved H2O(g) and NH3(g) is influenced by the adsorption of NH4+(aq) at pHi 8-10 and by the low percentage of struvite at pHi 11. Overall, results indicate that both the amount of P recovered and the fraction of struvite are optimized at pHi 10. These findings can be used as a starting point in the selection of a suitable pHi for struvite recovery from nutrient-rich wastes.",

keywords = "P NMR, P fertilizer, P recovery, P sustainability, Simultaneous thermal analysis, Struvite, Wastewater",

author = "Ning Ma and Rouff, {Ashaki A.} and Phillips, {Brian L.}",

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doi = "10.1021/sc4004746",

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T1 - A 31P NMR and TG/DSC-FTIR investigation of the influence of initial pH on phosphorus recovery as struvite

AU - Ma, Ning

AU - Rouff, Ashaki A.

AU - Phillips, Brian L.

PY - 2014/4/7

Y1 - 2014/4/7

N2 - Phosphorus can be reclaimed from nutrient-rich sources as the mineral struvite (MgNH4PO4·6H2O) for reuse as fertilizer. This study determines the impact of initial pH (pHi) from 8 to 11 on the fraction of precipitated struvite from a MgCl 2-(NH4)2HPO4-NaCl-H2O system. The rate of P removal from solution increases with pHi and maximizes at pHi 10. Scanning electron microscopy (SEM) of recovered precipitates shows changes in morphology and decreasing particle size with increasing pHi. 31P nuclear magnetic resonance spectroscopy (NMR) confirms that struvite constitutes 96-99% of the phosphate at pHi 8-10, with newberyite (MgHPO4·3H2O) as a minor crystalline phase. At pHi 11, 60% of the solid is struvite, with 22% of the phosphate contained in an amorphous phase and 18% as sodium phosphate. Thermogravimetric analysis (TG) reveals a correlation in the mass loss from the solids with the percentage of struvite detected. Coupling Fourier transform infrared spectroscopy (FT-IR) with TG indicates that the molar concentration of evolved H2O(g) and NH3(g) is influenced by the adsorption of NH4+(aq) at pHi 8-10 and by the low percentage of struvite at pHi 11. Overall, results indicate that both the amount of P recovered and the fraction of struvite are optimized at pHi 10. These findings can be used as a starting point in the selection of a suitable pHi for struvite recovery from nutrient-rich wastes.

AB - Phosphorus can be reclaimed from nutrient-rich sources as the mineral struvite (MgNH4PO4·6H2O) for reuse as fertilizer. This study determines the impact of initial pH (pHi) from 8 to 11 on the fraction of precipitated struvite from a MgCl 2-(NH4)2HPO4-NaCl-H2O system. The rate of P removal from solution increases with pHi and maximizes at pHi 10. Scanning electron microscopy (SEM) of recovered precipitates shows changes in morphology and decreasing particle size with increasing pHi. 31P nuclear magnetic resonance spectroscopy (NMR) confirms that struvite constitutes 96-99% of the phosphate at pHi 8-10, with newberyite (MgHPO4·3H2O) as a minor crystalline phase. At pHi 11, 60% of the solid is struvite, with 22% of the phosphate contained in an amorphous phase and 18% as sodium phosphate. Thermogravimetric analysis (TG) reveals a correlation in the mass loss from the solids with the percentage of struvite detected. Coupling Fourier transform infrared spectroscopy (FT-IR) with TG indicates that the molar concentration of evolved H2O(g) and NH3(g) is influenced by the adsorption of NH4+(aq) at pHi 8-10 and by the low percentage of struvite at pHi 11. Overall, results indicate that both the amount of P recovered and the fraction of struvite are optimized at pHi 10. These findings can be used as a starting point in the selection of a suitable pHi for struvite recovery from nutrient-rich wastes.

KW - P NMR

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KW - P sustainability

KW - Simultaneous thermal analysis

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KW - Wastewater

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