Describing the adsorption of phosphate, citrate and selenite on a variable-charge mineral surface

J. W. Bowden, S. Nagarajah, N. J. Barrow, A. M. Posner, J. P. Quirk

Research output: Contribution to journalArticle

213 Citations (Scopus)

Abstract

The effects were measured of varying the pH and the concentration of adsorbing ion on adsorption of phosphate, citrate and selenite by goethite and on the charge conveyed to the surface. The ability of the model of Bowden et al. to describe these effects was investigated. The observed effects were closely described by the model, provided it was modified to permit the adsorbed ions to reside in a plane between the surface and the diffuse layer. The model requires that individual ionic species be considered. For phosphate and selenite, the divalent ion appeared to be the only ion adsorbed whereas for citrate it was the trivalent ion. The model also requires that adsorption depends on the electrostatic potential in the plane of adsorption. This potential decreases with increasing pH. Thus the effects of pH on adsorption were explained by changes in this potential, together with changes in the proportion of the ionic species present. Because adsorption made the surface more negative, it also decreased the electrostatic potential in the plane of adsorption. This made further adsorption more difficult, and as a result, adsorption at a constant pH did not follow the Langmuir equation. The model showed that the increase in negative charge as a result of adsorption was partly balanced by an uptake of protons by the surface. This was most marked at near-neutral pH and as a result the net charge per adsorbed ion was least.

Original languageEnglish
Pages (from-to)49-60
Number of pages12
JournalAustralian Journal of Soil Research
Volume18
Issue number1
DOIs
Publication statusPublished - 1 Jan 1980

Fingerprint

variable charge
Selenious Acid
selenites
selenite
Citric Acid
citrates
Minerals
adsorption
Phosphates
phosphate
phosphates
minerals
Adsorption
mineral
Ions
ions
ion
Electrostatics
goethite
protons

Cite this

Bowden, J. W. ; Nagarajah, S. ; Barrow, N. J. ; Posner, A. M. ; Quirk, J. P. / Describing the adsorption of phosphate, citrate and selenite on a variable-charge mineral surface. In: Australian Journal of Soil Research. 1980 ; Vol. 18, No. 1. pp. 49-60.
@article{62e773441df841c496f2aa8b40115a7a,
title = "Describing the adsorption of phosphate, citrate and selenite on a variable-charge mineral surface",
abstract = "The effects were measured of varying the pH and the concentration of adsorbing ion on adsorption of phosphate, citrate and selenite by goethite and on the charge conveyed to the surface. The ability of the model of Bowden et al. to describe these effects was investigated. The observed effects were closely described by the model, provided it was modified to permit the adsorbed ions to reside in a plane between the surface and the diffuse layer. The model requires that individual ionic species be considered. For phosphate and selenite, the divalent ion appeared to be the only ion adsorbed whereas for citrate it was the trivalent ion. The model also requires that adsorption depends on the electrostatic potential in the plane of adsorption. This potential decreases with increasing pH. Thus the effects of pH on adsorption were explained by changes in this potential, together with changes in the proportion of the ionic species present. Because adsorption made the surface more negative, it also decreased the electrostatic potential in the plane of adsorption. This made further adsorption more difficult, and as a result, adsorption at a constant pH did not follow the Langmuir equation. The model showed that the increase in negative charge as a result of adsorption was partly balanced by an uptake of protons by the surface. This was most marked at near-neutral pH and as a result the net charge per adsorbed ion was least.",
author = "Bowden, {J. W.} and S. Nagarajah and Barrow, {N. J.} and Posner, {A. M.} and Quirk, {J. P.}",
year = "1980",
month = "1",
day = "1",
doi = "10.1071/SR9800049",
language = "English",
volume = "18",
pages = "49--60",
journal = "Australian Journal of Soil Research",
issn = "0004-9573",
publisher = "Blackwell",
number = "1",

}

Describing the adsorption of phosphate, citrate and selenite on a variable-charge mineral surface. / Bowden, J. W.; Nagarajah, S.; Barrow, N. J.; Posner, A. M.; Quirk, J. P.

In: Australian Journal of Soil Research, Vol. 18, No. 1, 01.01.1980, p. 49-60.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Describing the adsorption of phosphate, citrate and selenite on a variable-charge mineral surface

AU - Bowden, J. W.

AU - Nagarajah, S.

AU - Barrow, N. J.

AU - Posner, A. M.

AU - Quirk, J. P.

PY - 1980/1/1

Y1 - 1980/1/1

N2 - The effects were measured of varying the pH and the concentration of adsorbing ion on adsorption of phosphate, citrate and selenite by goethite and on the charge conveyed to the surface. The ability of the model of Bowden et al. to describe these effects was investigated. The observed effects were closely described by the model, provided it was modified to permit the adsorbed ions to reside in a plane between the surface and the diffuse layer. The model requires that individual ionic species be considered. For phosphate and selenite, the divalent ion appeared to be the only ion adsorbed whereas for citrate it was the trivalent ion. The model also requires that adsorption depends on the electrostatic potential in the plane of adsorption. This potential decreases with increasing pH. Thus the effects of pH on adsorption were explained by changes in this potential, together with changes in the proportion of the ionic species present. Because adsorption made the surface more negative, it also decreased the electrostatic potential in the plane of adsorption. This made further adsorption more difficult, and as a result, adsorption at a constant pH did not follow the Langmuir equation. The model showed that the increase in negative charge as a result of adsorption was partly balanced by an uptake of protons by the surface. This was most marked at near-neutral pH and as a result the net charge per adsorbed ion was least.

AB - The effects were measured of varying the pH and the concentration of adsorbing ion on adsorption of phosphate, citrate and selenite by goethite and on the charge conveyed to the surface. The ability of the model of Bowden et al. to describe these effects was investigated. The observed effects were closely described by the model, provided it was modified to permit the adsorbed ions to reside in a plane between the surface and the diffuse layer. The model requires that individual ionic species be considered. For phosphate and selenite, the divalent ion appeared to be the only ion adsorbed whereas for citrate it was the trivalent ion. The model also requires that adsorption depends on the electrostatic potential in the plane of adsorption. This potential decreases with increasing pH. Thus the effects of pH on adsorption were explained by changes in this potential, together with changes in the proportion of the ionic species present. Because adsorption made the surface more negative, it also decreased the electrostatic potential in the plane of adsorption. This made further adsorption more difficult, and as a result, adsorption at a constant pH did not follow the Langmuir equation. The model showed that the increase in negative charge as a result of adsorption was partly balanced by an uptake of protons by the surface. This was most marked at near-neutral pH and as a result the net charge per adsorbed ion was least.

UR - http://www.scopus.com/inward/record.url?scp=33746775129&partnerID=8YFLogxK

U2 - 10.1071/SR9800049

DO - 10.1071/SR9800049

M3 - Article

VL - 18

SP - 49

EP - 60

JO - Australian Journal of Soil Research

JF - Australian Journal of Soil Research

SN - 0004-9573

IS - 1

ER -