The Inhibition of C-steel Corrosion in H3PO4Solution by Some Furfural Hydrazone Derivatives

Abstract

The effect of some furfural hydrazone derivatives (I -V) as corrosion inhibitors for C-steel in 3M H 3 PO 4 solution in which M indicates mol/l has been studied using weight-loss and galvanostatic polarization techniques. A significant decrease in the corrosion rate of C-steel was observed in the presence of the investigated compounds. This study revealed that, the inhibition efficiency increases with increasing the inhibitor concentration, and the addition of iodide and thiocynate ions enhances it to a considerable extent. The effect of temperature on the corrosion behavior of C-steel was studied in the range from 30-60°C with and without 5×10 -6 M investigated compounds using weight-loss method. Apparent activation corrosion energy (E a *) and other thermodynamic parameters for the corrosion process were calculated and discussed. The polarization measurements show that the investigated compounds act as mixed-type inhibitors, but the cathode is more polarized when an external current was applied. The adsorption of these compounds on the surface of C-steel in 3 M H 3 PO 4 obeys Frumkin's adsorption isotherm. The mechanism of inhibition was discussed in the light of the chemical structure of the investigated compounds.