Graduation Year

2015

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Geology

Major Professor

Matthew A. Pasek, Ph.D.

Committee Member

Jeffrey Ryan, Ph.D.

Committee Member

Zachary Atlas, Ph.D.

Keywords

chemical evolution of life, meteorite minerals, phosphides

Abstract

We present study of the synthesis and reactions of an analog of the meteoritic mineral schreibersite with formula (Fe,Ni)3P, believed to be a prebiotic source of reactive phosphorus that may have prompted the formation of phosphorylated biomolecules near the time of the origin of life (Pasek and Lauretta, 2005). The mineral was synthesized by mixing stoichiometric proportions of elemental iron, nickel and phosphorus and heating in a tube furnace at 820°C for approximately 235 hours under argon or under vacuum, a modification of the method of Skála and Drábek (2002). The mineral was characterized using X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), micro-raman spectroscopy and electron microprobe analysis (EMPA). Characterization indicates that both schreibersite, with approximate formula Fe2NiP and the mineral nickel-phosphide, FeNi2P were synthesized.

In addition to characterization of the solid product, the reactions of the synthetic schreibersite were investigated to determine the similarity between these and prior work done with Fe3P. Synthetic schreibersite was corroded in several solutions: seawater and sulfidic water under both oxic and anoxic conditions. After corrosion, the solutions were analyzed using phosphorus nuclear magnetic resonance spectroscopy (31P NMR) and high performance liquid chromatography attached to an inductively coupled plasma mass spectrometer (HPLC-ICP-MS) to determine phosphorus speciation as well as concentrations of phosphorus present in solution. As expected from previous studies, the NMR and HPLC-ICP-MS results indicated the presence of orthophosphate, phosphite, pyrophosphate and hypophosphate in the corrosion solutions (Pasek and Lauretta, 2005). The HPLC-ICP-MS results indicate that the extent of corrosion of the mineral—measured by the concentration of phosphorus released—depends on the ionic strength of the solution, as well as the presence or absence of the chelating agent. Finally, we report the successful phosphorylation of a potentially prebiotic molecule—choline—using synthesized schreibersite.

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