| Autor: |
Marcelo Javier Avena, Carlos P. De Pauli |
| Rok vydání: |
1996 |
| Předmět: |
|
| Zdroj: |
Colloids and Surfaces A: Physicochemical and Engineering Aspects. 108:181-189 |
| ISSN: |
0927-7757 |
| DOI: |
10.1016/0927-7757(95)03394-7 |
| Popis: |
Results related to the dissolution mechanism of β-Ni(OH)2 particles in acidic (HClO4) media are reported. The influence of the H+ concentration and temperature on the dissolution kinetics of these particles was followed using a turbidimetric method, which appeared to be a useful tool for this kind of study. Surface charge (H+ adsorption) and electrokinetic measurements were also used to characterize the adsorption and charging behavior of the Ni(OH)2-aqueous solution interface. The point of zero charge was in the pH 10.4±0.2 range. Protons as well as temperature promoted the dissolution of Ni(OH)2. All the studied samples exhibited a fractional reaction order of 0.35±0.03 when the dissolution rate law was expressed in terms of the H+ concentration in the aqueous solution; conversely, an integer reaction order of 2 was found when the rate law was expressed in terms of protonated surface site density. The results suggest that Ni(OH)2 dissolves through a surface-controlled reaction in which two proton adsorption steps precede the detachment of Ni(II) species. The apparent activation energy of the process was 9–10 kcal mol−1. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect