Abstract
The pH of a soil was altered by incubating it with either lime or acid at 60°C for 1 day. Subsamples were then mixed with fluoride solutions in order to measure the effects of pH on fluoride retention. The results were compared with those previously obtained with phosphate on the same soil. At equal concentration of total fluorine in solution, fluoride retention was greatest at about pH 5.5 and decreased at both lower and higher pH. The decrease at low pH appeared to be caused by the formation of complexes between fluoride and aluminium in solution. As a result, only a small proportion of the total fluorine in solution was present as fluoride ions. At equal concentrations of fluoride ions, fluoride retention decreased with increasing pH. It was shown that this decrease could be explained by decreases in the electrostatic potential of the variable charge materials. The decrease in potential was steeper than that required to describe phosphate retention. This is consistent with the plane of adsorption of fluoride ions being closer to the plane of adsorption of H+ and OH− ions.
| Original language | English |
|---|---|
| Pages (from-to) | 287-293 |
| Number of pages | 7 |
| Journal | Journal of Soil Science |
| Volume | 37 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 1 Jan 1986 |
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Testing a mechanistic model. III. The effects of pH on fluoride retention by a soil. / BARROW, N. J.; ELLIS, A. S.
In: Journal of Soil Science, Vol. 37, No. 2, 01.01.1986, p. 287-293.Research output: Contribution to journal › Article
TY - JOUR
T1 - Testing a mechanistic model. III. The effects of pH on fluoride retention by a soil
AU - BARROW, N. J.
AU - ELLIS, A. S.
PY - 1986/1/1
Y1 - 1986/1/1
N2 - The pH of a soil was altered by incubating it with either lime or acid at 60°C for 1 day. Subsamples were then mixed with fluoride solutions in order to measure the effects of pH on fluoride retention. The results were compared with those previously obtained with phosphate on the same soil. At equal concentration of total fluorine in solution, fluoride retention was greatest at about pH 5.5 and decreased at both lower and higher pH. The decrease at low pH appeared to be caused by the formation of complexes between fluoride and aluminium in solution. As a result, only a small proportion of the total fluorine in solution was present as fluoride ions. At equal concentrations of fluoride ions, fluoride retention decreased with increasing pH. It was shown that this decrease could be explained by decreases in the electrostatic potential of the variable charge materials. The decrease in potential was steeper than that required to describe phosphate retention. This is consistent with the plane of adsorption of fluoride ions being closer to the plane of adsorption of H+ and OH− ions.
AB - The pH of a soil was altered by incubating it with either lime or acid at 60°C for 1 day. Subsamples were then mixed with fluoride solutions in order to measure the effects of pH on fluoride retention. The results were compared with those previously obtained with phosphate on the same soil. At equal concentration of total fluorine in solution, fluoride retention was greatest at about pH 5.5 and decreased at both lower and higher pH. The decrease at low pH appeared to be caused by the formation of complexes between fluoride and aluminium in solution. As a result, only a small proportion of the total fluorine in solution was present as fluoride ions. At equal concentrations of fluoride ions, fluoride retention decreased with increasing pH. It was shown that this decrease could be explained by decreases in the electrostatic potential of the variable charge materials. The decrease in potential was steeper than that required to describe phosphate retention. This is consistent with the plane of adsorption of fluoride ions being closer to the plane of adsorption of H+ and OH− ions.
UR - http://www.scopus.com/inward/record.url?scp=0022927579&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2389.1986.tb00030.x
DO - 10.1111/j.1365-2389.1986.tb00030.x
M3 - Article
VL - 37
SP - 287
EP - 293
JO - Journal of Soil Science
JF - Journal of Soil Science
SN - 0022-4588
IS - 2
ER -