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Phosphate desorption from kaolinite suspensions
Year:
1978
Authors :
Bar-Yosef, Bnayahu
;
.
Kafkafi, Uzi
;
.
Volume :
42
Co-Authors:

B. Bar‐Yosef  

U. Kafkafi

Facilitators :
From page:
570
To page:
574
(
Total pages:
5
)
Abstract:

Phosphate desorption from soil minerals is one of the factors which determine the rate of P uptake by plants. Under laboratory conditions desorption is usually obtained by drastic dilution or leaching of the clay, thus inducing its dissolution. The objective of this work was to study the effect of the desorption method used, equilibration time and the dissolved silica on the desorption of P from kaolinite. Two desorption methods were used: (i) diluting 1% suspensions by various volumes of the same electrolyte, and (ii) immersing a dialysis tube containing 0.25% suspension (+P) in an identical suspension initially free of P. The desorption process in both cases could be divided into a rapid and a slow first‐order reaction. The rapid reaction rate constant was similar in both systems (about 4.65 × 10−3hours−1 at 25°C). The slow reaction constants were 0.3 × 10−3hours−1 and 1.15 × 10−3hours−1 for cases (i) and (ii), respectively. The activation energy of the desorption process in case (ii) was 16.2 Kcal/mole for the rapid and 4.8 Kcal/mole for the slow reaction. The amount of silica dissolved from kaolinite due to dilution with 0.01M KCl depended on the dilution ratio and reached 16 mg SiO2/g kaolinite when the suspension was diluted 100‐fold. Readsorption of part of the dissolved silica is stipulated to contribute to the fast P desorption process.

Note:
Related Files :
soil
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More details
DOI :
10.2136/sssaj1978.03615995004200040007x
Article number:
0
Affiliations:
Database:
Publication Type:
article
;
.
Language:
English
Editors' remarks:
ID:
52809
Last updated date:
02/03/2022 17:27
Creation date:
29/12/2020 23:04
Scientific Publication
Phosphate desorption from kaolinite suspensions
42

B. Bar‐Yosef  

U. Kafkafi

Phosphate desorption from kaolinite suspensions

Phosphate desorption from soil minerals is one of the factors which determine the rate of P uptake by plants. Under laboratory conditions desorption is usually obtained by drastic dilution or leaching of the clay, thus inducing its dissolution. The objective of this work was to study the effect of the desorption method used, equilibration time and the dissolved silica on the desorption of P from kaolinite. Two desorption methods were used: (i) diluting 1% suspensions by various volumes of the same electrolyte, and (ii) immersing a dialysis tube containing 0.25% suspension (+P) in an identical suspension initially free of P. The desorption process in both cases could be divided into a rapid and a slow first‐order reaction. The rapid reaction rate constant was similar in both systems (about 4.65 × 10−3hours−1 at 25°C). The slow reaction constants were 0.3 × 10−3hours−1 and 1.15 × 10−3hours−1 for cases (i) and (ii), respectively. The activation energy of the desorption process in case (ii) was 16.2 Kcal/mole for the rapid and 4.8 Kcal/mole for the slow reaction. The amount of silica dissolved from kaolinite due to dilution with 0.01M KCl depended on the dilution ratio and reached 16 mg SiO2/g kaolinite when the suspension was diluted 100‐fold. Readsorption of part of the dissolved silica is stipulated to contribute to the fast P desorption process.

Scientific Publication
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