PROTECTIVE PROPERTIES OF SOME THIADIAZOLE DERIVATIVES IN SULFURIC ACID SOLUTIONS

The work presents the results of the study of some thiadiazole derivatives as corrosion inhibitors for mild steel in 5-20% H2SO4. Gravimetric tests and electrochemical studies were performed on low-carbon steel St3 at ambient temperature. The exposure time of the samples was 24 h. Polarization curves were obtained by potentiodynamic method (v = 1 mV/s) in a three-electrode cell, using the SOLARTRON 1280 C electrochemical measuring complex. The following thiadiazole derivatives were studied: (E)-N, N-dimethyl-4-{[(5-phenyl-1,3,4-thiadiazol-2-yl)imino]methyl} aniline, (E)-5-{[4-(dimethylamino)benzylidene] amino}-1,3,4-thiadiazol-2-thiol, (E)-4-{[(5-(furan-2-yl)-1,3,4-thiadiazol- 2-yl) imino] methyl}-N,N-dimethylaniline, N-(1,3,4-thiadiazol-2-yl) acetamide. It was established that the studied compounds at a concentration of 0.1-0.2 g/l show a good protective effect. The best result is given by (E)-5-{[4- (dimethylamino)benzylidene]amino}-1,3,4-thiadiazol-2-thiol with a protective effect Z more than 90%. The introduction of the benzene ring and the furan fragment into the molecules of the compounds under study leads to a decrease in their protective action as compared with the thiol group. With the help of electrochemical studies it was shown that the compounds studied are inhibitors of a mixed (cathodic-anodic) type, but to a greater extent they reduced the rate of the cathodic process. The results of the work indicate the promise of searching for potential acid corrosion inhibitors in a series of thiadiazole derivatives and the development of inhibiting compositions based on them.