THERMODYNAMIC PARAMETERS OF INHIBITION OF ALUMINUM DISSOLUTION IN OXALIC ACID SOLUTIONS USING SOME ORGANIC COMPOUNDS | ||||
| Al-Azhar Bulletin of Science | ||||
| Article 2, Volume 17, Issue 2-A, December 2006, Page 27-41 PDF (761.99 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/absb.2006.11651 | ||||
 View on SCiNiTO | ||||
| Author | ||||
| S. A. SOLIMAN* | ||||
| Chemistry Dept., Faculty of Science, Al-Azhar University, Cairo, Egypt | ||||
| Abstract | ||||
| Corrosion of aluminum in oxalic acid has been done by using wt-loss technique and polarization technique in presence of different concentrations of different organic derivatives of (5-Acetyl, 3-Cyano, 6-Methyl, 2-Thiopyridone, …) such as (…, 4-p Anisyl [A1]), (…,4-p Bromo phenyl [A2]), (…, 4-p Tolyl, [A3]), (…,4-p Nitro phenyl [A4]) and (…,4-p Chloro phenyl [A5]) at different temperatures. It is noticed from the observed thermodynamic parameters derived from wt-loss measurements that ∆H for the adsorption of A1, A2, A3 and A5 resulted in a negative value (exothermic), the adsorption typed is chemical adsorption, whereas A4 acquired physical adsorption and accelerated the dissolution of aluminum. This behavior is also observed at high temperatures for A5 compound. From the polarization method studied the dissolution of aluminum in oxalic acid is decreasing as the concentration of the acid increased due to the formation of oxide passive layer (Al2O3. 3H2O), the application of Evans diagram showed that the used compounds A1, A2, A3 and A5 can act as anodic inhibitors. | ||||
| Keywords | ||||
| Thermodynamic parameters; ALUMINUM DISSOLUTION; oxalic acid | ||||
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