Effect of sodium tungstate, sodium molybdate and thiourea on corrosion of aluminum in oxalic acid solution

Abstract EN

Corrosion of aluminum in oxalic acid has been investigated by using wt-loss technique in the absence and in the presence of different additive compounds (sodium tungstate [ST], sodium molybdate [SM] and thiourea [TU]) at different temperatures.

It was observed from the thermodynamic parameters, which derived from wt-loss measurements that the ∆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 decreases with increasing the concentration of the acid.

This is due to the collective properties of organic acid where the oxalic acid behaves as dimmer form at different concentrations.

The dissolution of aluminum in oxalic acid decreased after short period due to the fast formation of oxide passive layer [Al2O3.3H2O].