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Influence of Inorganic Anions on the Speciation of Mononuclear and Polynuclear Aluminum by Ferron
Author(s) -
Jardine P. M.,
Zelazny L. W.
Publication year - 1987
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1987.03615995005100040009x
Subject(s) - chemistry , ion , nuclear chemistry , medicinal chemistry , inorganic chemistry , organic chemistry
The kinetic reactions of ferron (8‐hydroxy‐7‐iodo‐5‐quinoline‐sulfonic acid) with unneutralized and partially neutralized Al solutions in the presence of various inorganic anions were investigated for the purpose of differentiating mononuclear and polynuclear Al. Development of a general order reaction function indicated that ferron interactions with Al were modeled best by second‐order rate expressions. Mononuclear Al solutions containing ClO ‐ 4 , Cl ‐ , NO ‐ 3 , SO 2‐ 4 , H 2 PO ‐ 4 , and F ‐ with anion to Al molar ratios of 13, 21, 15, 5, 0.75, and 0.08, respectively, expressed similar reactions with ferron that conformed to a single second‐order reaction. Ferron interactions with partially neutralized Al‐anion solutions were described by two simultaneous second‐order reactions that provided the rate of Al‐polymer interactions with ferron, k b , and the mole fraction of mononuclear Al species present, f a . Distinction of mononuclear and polynuclear Al in partially neutralized solutions with various anions is possible using ferron if the H 2 PO ‐ 4 /Al and F ‐ /Al molar ratios do not exceed ≈ 0.75 and 0.08, respectively. Phosphate and F ‐ concentrations that reduce these ratios and SO 2‐ 4 /Al ratios of ≈ 5 still form complexes with Al, but are easily degraded by ferron and react identically to uncomplexed mononuclear Al solutions. Such complexes must be accounted for if an estimate of toxic mononuclear Al [Al(H 2 O) 3+ 6 , AlOH(H 2 O) 2+ 5 , Al(OH) 2 (H 2 O) + 4 ] is desired.