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Self‐Diffusion of Selenate and Selenite in Overburden
Author(s) -
Ahlrichs J. S.,
Hossner L. R.
Publication year - 1989
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1989.00472425001800040014x
Subject(s) - selenate , selenium , diffusion , chemistry , overburden , analytical chemistry (journal) , environmental chemistry , geology , physics , geotechnical engineering , thermodynamics , organic chemistry
Self‐diffusion coefficients ( D ) for selenate (SeO 2− 4 ) and selenite (HSeO − 3 ) were evaluated as a function of overburden pH (2, 3, 5, 7, 9) and volumetric water content (Θ v = 0.22, 0.28, 0.34). Selenate self‐diffusion coefficients were least ( D = 0.23 × 10 −6 cm 2 s −1 in overburden adjusted to pH 3 and Θ v = 0.22 and greatest ( D = 1.8 × 10 −6 cm 2 s −1 and 1.7 × 10 −6 cm 2 s −1 ) in overburden adjusted to pH 9 and Θ v = 0.28 and 0.34. Self‐diffusion coefficients for HSeO − 3 were 2 to 3 orders of magnitude slower than for SeO 2− 4 . The most rapid HSeO − 3 diffusion was observed at pH 2 and Θ v = 0.34 ( D = 53.2 × 10 −9 cm 2 s −1 ). The slowest was at pH 3 and Θ v = 0.22 ( D = 0.2 × 10 −9 cm 2 s −1 ). For both SeO 2− 4 and HSeO − 3 the self‐diffusion coefficients increased with increasing water content and were related to adsorption characteristics of the soil and the Se species present at each soil pH.