The study of thiadiazole derivatives as potential corrosion inhibitors of low-carbon steel in hydrochloric acid

The inhibition effect of series of thiadiazole derivatives against the corrosion of mild steel in 15 % HCl was studied by weight-loss method and electrochemical measurements. The experiments were performed on steel St3 at 293 K, the exposure time of the samples in solution for weight-loss measurements was 24 h. Potentiodynamic polarization curves were obtained in a typical three electrode cell with the help of electrochemical measuring complex SOLARTRON 1280 C. A scan rate was 1 mV⋅s-1 and a measurement point was taken every 0.2 s. 2-aminothiazole, 5-amino-1,3,4-thiadiazole-2-thiol, 2-amino-1,3,4-thiadiazole, 2-amino-5-(furan-2-yl)- 1,3,4-thiadiazole, 1,3,4-thiadiazole-2-ylamide of acetic acid were studied as potential inhibitors. The maximal inhibition efficiency was obtained at concentration 0.10-0.20 g⋅L−1. The best result was demonstrated by 5-amino-1,3,4-thiadiazole-2-thiol (inhibition effect was more than 90 %). The minimal inhibition effect had 1,3,4-thiadiazole-2-ylamide acetic acid. The corrosion inhibition effect calculated from data of the corrosion current density and from the weight-loss measurements were in sufficiently good agreement. The effective activation energy of the corrosion of St3 increased significantly due the presence of the inhibitors (from 3.3 to 94.8 kJ⋅mol-1). The results point to promising of investigating of series of thiadiazole derivatives and inhibitory compositions based on thiadiazole as potential acid corrosion inhibitors.