Sorption of Copper(II) on Aluminum Hydroxide as Affected by Phosphate1
- M. B. McBride2
The mechanisms of Cu2+ bonding on noncrystalline aluminum hydroxide with or without various levels of presorbed phosphate have been studied by the technique of electron spin resonance. Evidence for two separate chemisorption sites in the absence of phosphate is presented. At high levels of Cu2+ adsorption, discrete site chemisorption is replaced by nucleation or precipitation of hydroxy-Cu species at the surface. High levels of sorbed phosphate suppress Cu2+ adsorption, blocking the coordination of Cu2+ to AIOH groups on aluminum hydroxide. It is proposed that the decreased adsorption of Cu2+ observed in this study was a result of the weaker coordination of Cu2+ to the phosphate-coated surface than to the alumina surface in the absence of phosphate. The enhanced adsorption of metal ions on oxide and hydroxide surfaces following phosphate sorption observed in other studies is attributed to a different mechanism, involving the formation of a ternary complex in which Cu bonds simultaneously to phosphate and the surface.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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