Adsorption of Oxalic Acid onto Hematite: Application of Surface Potential Measurements
The surface potential at the hematite/aqueous oxalic acid interface was measured by means of a hematite Single Crystal Electrode. This allowed the simultaneous interpretation of the surface potential, electrokinetic potential and adsorption data for the adsorption of oxalic acid onto a hematite surf...
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| Format: | Article |
| Language: | English |
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SAGE Publishing
2007-07-01
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| Series: | Adsorption Science & Technology |
| Online Access: | https://doi.org/10.1260/026361707783908300 |
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| author | Tajana Preočanin Željka Majić Davor Kovačević Nikola Kallay |
| author_facet | Tajana Preočanin Željka Majić Davor Kovačević Nikola Kallay |
| author_sort | Tajana Preočanin |
| collection | DOAJ |
| description | The surface potential at the hematite/aqueous oxalic acid interface was measured by means of a hematite Single Crystal Electrode. This allowed the simultaneous interpretation of the surface potential, electrokinetic potential and adsorption data for the adsorption of oxalic acid onto a hematite surface. Based on the Surface Complexation Model, this interpretation suggested that the oxalate ion is bound to a metal ion at the solid surface to form a singly-charged oxalate-surface complex, with the charge being exposed to the potential at the outer Helmholtz layer. A number of equilibrium parameters describing the interfacial equilibrium were obtained. Thus, for the two protonation steps of the surface sites, the thermodynamic equilibrium constants were log K 1 = 7.1 ± 0.4 and log K 2 = 5.2 ± 0.4, respectively. Two assumptions were tested with regard to the adsorption equilibrium constant, i.e. the charge of the surface complex is exposed to the inner surface potential, ψ 0 , or to the outer surface potential, ψ d . The constancy of the interfacial equilibrium constants led to the conclusion the latter assumption was the more appropriate. The observed value of the adsorption equilibrium constant was log K ads = 3.0 ± 0.8. It was shown that measurement of the surface potential by Single Crystal Electrodes is a helpful tool in elucidating the equilibrium behaviour of the complex at the interface. |
| format | Article |
| id | doaj-art-42dd59f91b434c8c914f359a8ac49d98 |
| institution | Kabale University |
| issn | 0263-6174 2048-4038 |
| language | English |
| publishDate | 2007-07-01 |
| publisher | SAGE Publishing |
| record_format | Article |
| series | Adsorption Science & Technology |
| spelling | doaj-art-42dd59f91b434c8c914f359a8ac49d982025-01-03T00:11:56ZengSAGE PublishingAdsorption Science & Technology0263-61742048-40382007-07-012510.1260/026361707783908300Adsorption of Oxalic Acid onto Hematite: Application of Surface Potential MeasurementsTajana PreočaninŽeljka MajićDavor KovačevićNikola KallayThe surface potential at the hematite/aqueous oxalic acid interface was measured by means of a hematite Single Crystal Electrode. This allowed the simultaneous interpretation of the surface potential, electrokinetic potential and adsorption data for the adsorption of oxalic acid onto a hematite surface. Based on the Surface Complexation Model, this interpretation suggested that the oxalate ion is bound to a metal ion at the solid surface to form a singly-charged oxalate-surface complex, with the charge being exposed to the potential at the outer Helmholtz layer. A number of equilibrium parameters describing the interfacial equilibrium were obtained. Thus, for the two protonation steps of the surface sites, the thermodynamic equilibrium constants were log K 1 = 7.1 ± 0.4 and log K 2 = 5.2 ± 0.4, respectively. Two assumptions were tested with regard to the adsorption equilibrium constant, i.e. the charge of the surface complex is exposed to the inner surface potential, ψ 0 , or to the outer surface potential, ψ d . The constancy of the interfacial equilibrium constants led to the conclusion the latter assumption was the more appropriate. The observed value of the adsorption equilibrium constant was log K ads = 3.0 ± 0.8. It was shown that measurement of the surface potential by Single Crystal Electrodes is a helpful tool in elucidating the equilibrium behaviour of the complex at the interface.https://doi.org/10.1260/026361707783908300 |
| spellingShingle | Tajana Preočanin Željka Majić Davor Kovačević Nikola Kallay Adsorption of Oxalic Acid onto Hematite: Application of Surface Potential Measurements Adsorption Science & Technology |
| title | Adsorption of Oxalic Acid onto Hematite: Application of Surface Potential Measurements |
| title_full | Adsorption of Oxalic Acid onto Hematite: Application of Surface Potential Measurements |
| title_fullStr | Adsorption of Oxalic Acid onto Hematite: Application of Surface Potential Measurements |
| title_full_unstemmed | Adsorption of Oxalic Acid onto Hematite: Application of Surface Potential Measurements |
| title_short | Adsorption of Oxalic Acid onto Hematite: Application of Surface Potential Measurements |
| title_sort | adsorption of oxalic acid onto hematite application of surface potential measurements |
| url | https://doi.org/10.1260/026361707783908300 |
| work_keys_str_mv | AT tajanapreocanin adsorptionofoxalicacidontohematiteapplicationofsurfacepotentialmeasurements AT zeljkamajic adsorptionofoxalicacidontohematiteapplicationofsurfacepotentialmeasurements AT davorkovacevic adsorptionofoxalicacidontohematiteapplicationofsurfacepotentialmeasurements AT nikolakallay adsorptionofoxalicacidontohematiteapplicationofsurfacepotentialmeasurements |