Experimental investigation on corrosion inhibition of thiourea on aluminum surface in 0.5 M H2SO4 acid solution

Effect of thiourea on corrosion resistance of aluminum in 0.5 M H₂SO₄ solution is experimentally investigated. Results show that the addition of thiourea inhibits the sulfuric acid corrosion of aluminum. The inhibition efficiency can be enhanced with an increase in thiourea concentration. It is found that Rp values increases and C _dl values decreases with increasing inhibitor concentration. The inhibition happens through adsorption of thiourea on the metal surface without modifying the mechanism of corrosion process. Inhibition efficiency obtained from all methods is in good agreement. The adsorption of inhibitor on aluminum surface from 0.5 M H₂SO₄ acid solution obeys Langmuir adsorption isotherm.

     

Adsorbtion and inhibition effect of thiourea on mild steel in acidic media

The effect of thiourea on electrochemical corrosion behavior of mild steel was investigated in 0.5M HCl solution at room temperature by electrochemical impedance spectroscopy (AC Impedance) and Tafel polarization (DC Polarization) methods. The results show that thiourea act as mixed type inhibitor. The inhibition efficiency obtained from AC Impedance and DC polarization methods are in good agreement. The Nyquist plots show that the corrosion behavior of mild steel in 0.5M HCl solution in the absence and in the presence of thiourea, consist a simple capacitive loop. Changes in impedance parameters (R_ct and C_dl) are indicative of adsorption of thiourea on the metal surface, leading to the formation of protective film. Thiourea is found to adsorb on mild steel surface steel in 0.5M HCl solution, according to the Langmuir adsorption isotherm.