Composition of aluminum phosphate solutions. Evidence from aluminum-27 and phosphorus-31 nuclear magnetic resonance spectra

Journal Article · Thu Jun 01 04:00:00 EDT 1989 · Analytical Chemistry (Washington); (United States)

DOI:https://doi.org/10.1021/ac00186a016· OSTI ID:5348134

Wilson, M A; Collin, P J ^[1]; Akitt, J W ^[2]

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1. CSIRO Div. of Coal Technology, North Ryde, New South Wales (Australia)
2. Univ. of Leeds (England)

Low- (2.11 T) and high-field (9.4 T) {sup 27}Al and {sup 31}P nuclear magnetic resonance (NMR) spectrometry has been used to study the structure and reactivity of aluminum chloride solutions in the presence and absence of OH{sup {minus}}, H{sub 3}PO{sub 4}, H{sub 2}PO{sub 4}{sup {minus}}, HPO{sub 4}{sup 2{minus}}, and PO{sub 4}{sup 3{minus}} species. Evidence is presented for the existence of higher molecular weight complexes than the (AlO{sub 4}Al{sub 12}(OH){sub 24}(H{sub 2}O){sub 12}){sup 7+} cation in the presence of hydroxide ion. At high field, at least five types of complexed aluminum are observed by {sup 27}Al NMR in the presence of phosphate species. Three species at {minus}3.6, {minus}6.2, and {minus}7.6 ppm are observed in solutions containing predominantly H{sub 3}PO{sub 4}, and two species are observed in the presence of H{sub 2}PO{sub 4}{sup {minus}} at {minus}3.6 and {minus}7.6 ppm. It is proposed that the species at {minus}3.6 ppm has a Al:P ratio of 1. At least 11 resonances from different complexes in aluminum phosphate solutions can be observed by {sup 31}P NMR. It is shown that principal differences in chemical shift are due to the nature of the ligand (L = H{sub 3}PO{sub 4}, H{sub 2}PO{sub 4}{sup {minus}}, HPO{sub 4}{sup 2{minus}}) rather than the number of ligands (L{sub 1}, L{sub 2}, L{sub 3}, L{sub n}, etc.) in the complexes.

• OSTI ID: 5348134
• Journal Information: Analytical Chemistry (Washington); (United States), Journal Name: Analytical Chemistry (Washington); (United States) Vol. 61:11; ISSN 0003-2700; ISSN ANCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALUMINIUM 27
ALUMINIUM CHLORIDES
ALUMINIUM COMPOUNDS
ALUMINIUM ISOTOPES
ALUMINIUM PHOSPHATES
AQUEOUS SOLUTIONS
CHLORIDES
CHLORINE COMPOUNDS
DISPERSIONS
HALIDES
HALOGEN COMPOUNDS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MEASURING METHODS
MIXTURES
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS 31
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
RESONANCE
SOLUTIONS
STABLE ISOTOPES