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A NEW ADSORPTION ISOTHERM FOR PHOSPHATE IN SOIL
Author(s) -
GUNARY D.
Publication year - 1970
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1970.tb01153.x
Subject(s) - adsorption , phosphate , langmuir , freundlich equation , langmuir equation , chemistry , soil water , langmuir adsorption model , limiting , inorganic chemistry , geology , soil science , organic chemistry , mechanical engineering , engineering
Summary Phosphate adsorption data for 24 soils showed that although the Langmuir equation gave a good fit, there was significant curvature. Of the alternative equations examined, that of Freundlich provided a better description than that of Langmuir in 22 soils, but the best fit, accounting for more than 99·8 per cent of the variation in phosphate adsorption, was given by introducing a square‐root term:where y = adsorbed phosphate, c = equilibrium concentration of phosphate in solution, B, A , and D are constants. The phosphate adsorption maximum, obtained from I/ B , gave values in the range 325 to 1427 μg P/g soil which were 1·39 to 2·40 times those obtained from the Langmuir equation. The inclusion of a square‐root term in the Langmuir equation could be taken to imply that the soil will adsorb a little phosphate firmly, a slightly greater amount of phosphate less firmly, and so on until a limiting value is reached when all the components of the phosphate adsorption system are saturated.