Premium
Solubility of a proto‐imogolite sol in oxalate solutions
Author(s) -
LUMSDON D.G.,
FARMER V.C.
Publication year - 1997
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/j.1365-2389.1997.tb00190.x
Subject(s) - imogolite , allophane , oxalate , chemistry , solubility , calcium oxalate , inorganic chemistry , aluminium , calcium , nuclear chemistry , mineralogy , clay minerals , organic chemistry
Summary The amounts of aluminium liberated from a proto‐imogolite (P‐I) sol by 1–3 mM oxalate at pH 4·8–7·1 are found to be in excellent agreement with those calculated on the basis of the solubility product of the P‐I sol, and the stability constants for aluminium oxalate complexes established earlier. Calculated solubility curves are presented for proto‐imogolite sols in the presence of 10 −3 , 10 −4 and 10 −5 M total oxalate over the pH range 4–8, and also for the case where oxalate concentrations are controlled by solid calcium oxalate in the presence of 0·05, 0·5 and 5 mM calcium ion. We conclude that the presence of a proto‐imogolite allophane in podzol B horizons of pH 5·0 requires oxalate concentrations less than 10 −5 M. For fertile agricultural soils with typical calcium concentrations (approximately 5 mM) in the soil solution, aluminium oxalate concentrations would be limited by calcium oxalate solubility to less than 10 −6 M in the presence of proto‐imogolite allophane at pH values exceeding 5·5. In leached podzolic soils calcium concentrations are generally less than 0·05 mM, and would not limit the formation of aluminium oxalate complexes.