Effect of Sodium Tungstate, Sodium Molybdate and Thiourea on Corrosion of Aluminum in Oxalic Acid Solution

DR.S.R. SelimDR. Kh. A. S. Galeb , and G. M. A. Al-Maleeh

الملخص

Corrosion of aluminum in oxalic acid had been investigated by using wt- loss technique in absence and in presence of 0.001 M concentration of different additive compounds (sodium tungstate [ST], sodium molybdate [SM] and thiourea [TU]) at different temperature. It is noticed from the observed thermodynamic parameters derived from wt-loss measurements that ∆Had for the adsorption of ST, SM, and TU resulted in a positive value (endothermic), the adsorption typed is physical - chemical adsorption. The dissolution of aluminum in oxalic acid is decreasing as the concentration of the acid increased due to the collective properties of organic acid were the oxalic acid behave as dimmer molecular at different concentration. The dissolution of aluminum in oxalic acid decreased after short period due to fast formation of oxide passive layer [Al2O3.3H2O].