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BOUNDARY LAYER TRANSPORT OF METAL IONS IN FROZEN SOIL
Author(s) -
MOHAMED A. M. O.,
SHOOSHPASHA I.,
YONG R. N.
Publication year - 1996
Publication title -
international journal for numerical and analytical methods in geomechanics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.419
H-Index - 91
eISSN - 1096-9853
pISSN - 0363-9061
DOI - 10.1002/(sici)1096-9853(199610)20:10<693::aid-nag841>3.0.co;2-4
Subject(s) - moisture , distilled water , water content , chemistry , metal , ion , metal ions in aqueous solution , boundary layer , thermal diffusivity , materials science , analytical chemistry (journal) , soil science , mineralogy , chromatography , thermodynamics , geotechnical engineering , composite material , geology , physics , organic chemistry
Two series of freezing column tests with distilled water and municipal solid waste leachate were investigated, using illitic silty clay. Temperature distributions along the freezing column were recorded as a function of distance and time. Unfrozen moisture content and osmotic pressures as a function of temperature were calculated. It was shown that temperature distributions as a function of distance and time were similar in all tests, probably as a result of the limited amount of moisture intake. The amount of moisture intake was directly related to freezing time and temperature gradient in the freezing column. Unfrozen moisture contents, ion concentrations and temperature gradients were identified as the controlling parameters that contributed to the boundary layer transport (BLT) of metal ions in frozen specimens. Na + concentration profiles were mostly dependent on water movement in the freezing column. The behaviour of Ca 2+ and Mg 2+ cations was similar to Na + ; their concentrations in the soil solution decreased with freezing time due to ion exchange. Temperature, moisture content in an unfrozen boundary layer (UBL), and concentration gradient were taken into consideration in the development of a boundary layer transport model (BLTM). Based on the experimental results and Powell's optimization technique, the diffusivity parameters of various metal ions were calculated. Comparison of experimental and predicted results indicated that the BLTM can predict the migration of metal ions in UBL.