dc.contributor.author |
Pretorius, PJ
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en_US |
dc.contributor.author |
Linder, PW
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en_US |
dc.date.accessioned |
2007-02-06T13:36:09Z |
en_US |
dc.date.accessioned |
2007-06-07T10:01:43Z |
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dc.date.available |
2007-02-06T13:36:09Z |
en_US |
dc.date.available |
2007-06-07T10:01:43Z |
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dc.date.copyright |
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en_US |
dc.date.issued |
2001-07 |
en_US |
dc.identifier.citation |
Pretorius, PJ and Linder, PW. 2001. The adsorption characteristics of delta-manganese dioxide: a collection of diffuse double layer constants for the adsorption of H+, Cu2+, Ni2+, Zn2+, Cd2+ and Pb2+. Applied Geochemistry, vol. 16, 10 September, pp 1067-1082 |
en_US |
dc.identifier.issn |
0883-2927 |
en_US |
dc.identifier.uri |
http://hdl.handle.net/10204/1555
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en_US |
dc.identifier.uri |
http://hdl.handle.net/10204/1555
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|
dc.description.abstract |
Thermodynamic data for all fate-determining processes are needed in order to predict the fate and transport of metals in natural systems. The surface complexation properties of a synthetic MnO2, delta -MnO2, have accordingly been investigated using glass electrode potentiometry. Experimental data were interpreted according to the surface complexation model in conjunction with the diffuse double layer model of the solid/solution interface. Adsorption constants were determined using the non-linear optimisation program FITEQL. Surface complexation parameters determined in this way were validated against results obtained from the literature. Best fits of alkalimetric titration data were obtained with a 2-site, 3 surface-species model of the delta -MnO2 surface. Site concentrations of 2.23 x 10(-3) mol g (-1) and 7.66 x 10(-4) mol g (-1) were obtained. Corresponding logarithms of formation constants for the postulated surface species are -1.27 (=XO-), -5.99 (=YO-) and 3.52 (=YOH2+) at I = 0.1 M. The surface speciation of delta -MnO2 is dominated by =XO- over the pit range investigated. Metal adsorption was modelled with surface species of the type =XOM+, =XOMOH, =YOM+, =YOMOH (M = Cu, Ni, Zn, Cd and Pb) and =XOM2OH2+ (M = Pb). For Cu, Ni and Zn, titration data could be modelled with =XOM+, =XOMOH, =YOM+ and =YOMOH, whereas for Cd, =XOM+ and =YOM+ were sufficient. Lead data were best modelled by assuming the dinuclear species =XOM2OH2+ to be the only surface species to form. Adsorption constants determined for Ni, Cu and Zn follow the Irving-Williams sequence. The model suggests an adsorption order of (Pb, Cu) > (Ni, Zn) > Cd. The discrepancy between model predictions and published adsorption results is similar to the variability observed in experimental results from different laboratories. |
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dc.format.extent |
388868 bytes |
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dc.format.mimetype |
application/pdf |
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dc.language.iso |
en |
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dc.publisher |
Pergamon-Elsevier Science Ltd |
en_US |
dc.rights |
Copyright: 2001 Pergamon-Elsevier Science Ltd |
en_US |
dc.source |
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en_US |
dc.subject |
Glass electrode potentiometry |
en_US |
dc.subject |
Dinuclear species |
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dc.subject |
Potentiometric titrations |
en_US |
dc.subject |
Applied Geochemistry |
en_US |
dc.title |
Adsorption characteristics of delta-manganese dioxide: a collection of diffuse double layer constants for the adsorption of H+, Cu2+, Ni2+, Zn2+, Cd2+ and Pb2+ |
en_US |
dc.type |
Article |
en_US |
dc.identifier.apacitation |
Pretorius, P., & Linder, P. (2001). Adsorption characteristics of delta-manganese dioxide: a collection of diffuse double layer constants for the adsorption of H+, Cu2+, Ni2+, Zn2+, Cd2+ and Pb2+. http://hdl.handle.net/10204/1555 |
en_ZA |
dc.identifier.chicagocitation |
Pretorius, PJ, and PW Linder "Adsorption characteristics of delta-manganese dioxide: a collection of diffuse double layer constants for the adsorption of H+, Cu2+, Ni2+, Zn2+, Cd2+ and Pb2+." (2001) http://hdl.handle.net/10204/1555 |
en_ZA |
dc.identifier.vancouvercitation |
Pretorius P, Linder P. Adsorption characteristics of delta-manganese dioxide: a collection of diffuse double layer constants for the adsorption of H+, Cu2+, Ni2+, Zn2+, Cd2+ and Pb2+. 2001; http://hdl.handle.net/10204/1555. |
en_ZA |
dc.identifier.ris |
TY - Article
AU - Pretorius, PJ
AU - Linder, PW
AB - Thermodynamic data for all fate-determining processes are needed in order to predict the fate and transport of metals in natural systems. The surface complexation properties of a synthetic MnO2, delta -MnO2, have accordingly been investigated using glass electrode potentiometry. Experimental data were interpreted according to the surface complexation model in conjunction with the diffuse double layer model of the solid/solution interface. Adsorption constants were determined using the non-linear optimisation program FITEQL. Surface complexation parameters determined in this way were validated against results obtained from the literature. Best fits of alkalimetric titration data were obtained with a 2-site, 3 surface-species model of the delta -MnO2 surface. Site concentrations of 2.23 x 10(-3) mol g (-1) and 7.66 x 10(-4) mol g (-1) were obtained. Corresponding logarithms of formation constants for the postulated surface species are -1.27 (=XO-), -5.99 (=YO-) and 3.52 (=YOH2+) at I = 0.1 M. The surface speciation of delta -MnO2 is dominated by =XO- over the pit range investigated. Metal adsorption was modelled with surface species of the type =XOM+, =XOMOH, =YOM+, =YOMOH (M = Cu, Ni, Zn, Cd and Pb) and =XOM2OH2+ (M = Pb). For Cu, Ni and Zn, titration data could be modelled with =XOM+, =XOMOH, =YOM+ and =YOMOH, whereas for Cd, =XOM+ and =YOM+ were sufficient. Lead data were best modelled by assuming the dinuclear species =XOM2OH2+ to be the only surface species to form. Adsorption constants determined for Ni, Cu and Zn follow the Irving-Williams sequence. The model suggests an adsorption order of (Pb, Cu) > (Ni, Zn) > Cd. The discrepancy between model predictions and published adsorption results is similar to the variability observed in experimental results from different laboratories.
DA - 2001-07
DB - ResearchSpace
DP - CSIR
KW - Glass electrode potentiometry
KW - Dinuclear species
KW - Potentiometric titrations
KW - Applied Geochemistry
LK - https://researchspace.csir.co.za
PY - 2001
SM - 0883-2927
T1 - Adsorption characteristics of delta-manganese dioxide: a collection of diffuse double layer constants for the adsorption of H+, Cu2+, Ni2+, Zn2+, Cd2+ and Pb2+
TI - Adsorption characteristics of delta-manganese dioxide: a collection of diffuse double layer constants for the adsorption of H+, Cu2+, Ni2+, Zn2+, Cd2+ and Pb2+
UR - http://hdl.handle.net/10204/1555
ER -
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en_ZA |