Abstract
The sorption of Fe(II) and Mn(II) onto chitin has been measured in seawater as a function of pH (3-9), temperature (5-45°C), and salinity (0-35). The two metals showed markedly different pH effects. Uptake of Fe(II) was greatest at high pH, whereas Mn(II) showed negligible uptake above pH 6.3-7.3 and precipitated at high pH. The decrease in Mn(II) uptake above pH 6.3-7.3 could be related to the second acid dissociation site of chitin, which has p*Ka2 = 6.4. Fe(II) follows a Langmuir isotherm at pH 8.2 at intermediate concentrations, as did Mn(II) below pH 6.3. Uptake of both metals increased with temperature from 5 to 45°C, yielding a calculated sorption enthalpy of 14.2 ± 0.6 kJ mol-1 g-1 chitin for Fe(II) and 11 ± 3 kJ mol-1 g-1 for Mn(II) at pH 4. Increasing salinity from zero to 35 increased the uptake of Fe(II) by 50%; at pH 4 the Mn(II) uptake also increased substantially. Calculations indicate that uptake onto chitin-like material cannot account for the partitioning between dissolved and particulate forms of either Mn(II) or Fe(II) in two typical anoxic systems (the Black Sea and Framvaren fjord).
| Original language | English (US) |
|---|---|
| Pages (from-to) | 201-212 |
| Number of pages | 12 |
| Journal | Marine Chemistry |
| Volume | 33 |
| Issue number | 3 |
| DOIs | |
| State | Published - 1991 |
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ASJC Scopus subject areas
- Chemistry(all)
- Oceanography
Cite this
Uptake of Fe(II) and Mn(II) on chitin as a model organic phase. / Hawke, David J.; Sotolongo, Sara; Millero, Frank J.
In: Marine Chemistry, Vol. 33, No. 3, 1991, p. 201-212.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Uptake of Fe(II) and Mn(II) on chitin as a model organic phase
AU - Hawke, David J.
AU - Sotolongo, Sara
AU - Millero, Frank J
PY - 1991
Y1 - 1991
N2 - The sorption of Fe(II) and Mn(II) onto chitin has been measured in seawater as a function of pH (3-9), temperature (5-45°C), and salinity (0-35). The two metals showed markedly different pH effects. Uptake of Fe(II) was greatest at high pH, whereas Mn(II) showed negligible uptake above pH 6.3-7.3 and precipitated at high pH. The decrease in Mn(II) uptake above pH 6.3-7.3 could be related to the second acid dissociation site of chitin, which has p*Ka2 = 6.4. Fe(II) follows a Langmuir isotherm at pH 8.2 at intermediate concentrations, as did Mn(II) below pH 6.3. Uptake of both metals increased with temperature from 5 to 45°C, yielding a calculated sorption enthalpy of 14.2 ± 0.6 kJ mol-1 g-1 chitin for Fe(II) and 11 ± 3 kJ mol-1 g-1 for Mn(II) at pH 4. Increasing salinity from zero to 35 increased the uptake of Fe(II) by 50%; at pH 4 the Mn(II) uptake also increased substantially. Calculations indicate that uptake onto chitin-like material cannot account for the partitioning between dissolved and particulate forms of either Mn(II) or Fe(II) in two typical anoxic systems (the Black Sea and Framvaren fjord).
AB - The sorption of Fe(II) and Mn(II) onto chitin has been measured in seawater as a function of pH (3-9), temperature (5-45°C), and salinity (0-35). The two metals showed markedly different pH effects. Uptake of Fe(II) was greatest at high pH, whereas Mn(II) showed negligible uptake above pH 6.3-7.3 and precipitated at high pH. The decrease in Mn(II) uptake above pH 6.3-7.3 could be related to the second acid dissociation site of chitin, which has p*Ka2 = 6.4. Fe(II) follows a Langmuir isotherm at pH 8.2 at intermediate concentrations, as did Mn(II) below pH 6.3. Uptake of both metals increased with temperature from 5 to 45°C, yielding a calculated sorption enthalpy of 14.2 ± 0.6 kJ mol-1 g-1 chitin for Fe(II) and 11 ± 3 kJ mol-1 g-1 for Mn(II) at pH 4. Increasing salinity from zero to 35 increased the uptake of Fe(II) by 50%; at pH 4 the Mn(II) uptake also increased substantially. Calculations indicate that uptake onto chitin-like material cannot account for the partitioning between dissolved and particulate forms of either Mn(II) or Fe(II) in two typical anoxic systems (the Black Sea and Framvaren fjord).
UR - http://www.scopus.com/inward/record.url?scp=0026002256&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0026002256&partnerID=8YFLogxK
U2 - 10.1016/0304-4203(91)90067-7
DO - 10.1016/0304-4203(91)90067-7
M3 - Article
AN - SCOPUS:0026002256
VL - 33
SP - 201
EP - 212
JO - Marine Chemistry
JF - Marine Chemistry
SN - 0304-4203
IS - 3
ER -