Competitive Adsorption of Phosphate and Arsenate on Goethite
| Autor: | Zhao Hongshao, Robert Stanforth |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Minerals
Goethite Ion exchange Surface Properties Inorganic chemistry Arsenate Sorption General Chemistry Hydrogen-Ion Concentration Phosphate Phosphates Ion Kinetics chemistry.chemical_compound Adsorption Models Chemical chemistry Phase (matter) visual_art visual_art.visual_art_medium Arsenates Environmental Chemistry Iron Compounds |
| Zdroj: | Environmental Science & Technology. 35:4753-4757 |
| ISSN: | 1520-5851 0013-936X |
| Popis: | The competitive adsorption of phosphate and arsenate on goethite was investigated to better understand the bonding mechanisms for the two ions. The anions were added both simultaneously and sequentially. When added simultaneously, the two ions were adsorbed about equally, with the total surface coverage being slightly greater than for either ion alone. When added sequentially, the extent of exchange for the first ion depended on the equilibration time before the second ion was introduced--the longer the equilibration time the greater the exchange. There is a nonexchangeable fraction for both ions that is approximately equal to the initially adsorbed amount of each ion. The results suggest a two-phase reaction on the surface, with the first phase being a rapid surface complex formation on the goethite surface, followed by the slower buildup of a surface precipitate on the adsorbed layer. The exchangeable ions are in the surface precipitate. These results are incompatible with a surface complexation model (SCM) for anion adsorption on geothite and indicate that the actual reactions are more complicated than the reaction assumed in a SCM. |
| Databáze: | OpenAIRE |
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