The inhibition performances of thiadiazole derivatives

namely

2-amino-1

3

4-thiadiazole (ATD)

5-metheyl-2-amino-1

3

4-thiadiazole (MATD)

5-phenyl-2-amino-1

3

4-thiadiazole (PATD)

and 2

5-diphenyl- 1

3

4-thiadiazole (DPTD)

on silver strip corrosion in 50 mg·L-1 sulfur solution was studied using electrochemical impedance spectroscopy (EIS)

Tafel polarization techniques and atom force microscopy (AFM). These measurements showed that the addition inhibited silver strip corrosion

and the inhibitor formed a protected film on the silver strip surface. The inhibition efficiency decreased in the order of MATD > PATD > ATD > DPTD. The substitutes

which occupied 1 or 2 sites on the central five membered ring and had polar groups and non-polar groups properties and some active functional groups showed an important effect on the inhibition performance of thiadiazole derivatives. Compounds showed the best inhibitive efficiency when thiadiazole derivatives had the polar groups and the best inhibitive efficiency when non-polar groups were alkyl groups

because steric exclusion of aromatic groups decreased the adsorption. Kinetics analysis indicated that adsorption of the four inhibitors onto silver surface followed Langmuir adsorption isotherm. The adsorption belonged to mix-type adsorption mainly dominated by chemisorption. The inhibition mechanism of four corrosion inhibitors against sulfur corrosions was theoretically studied using molecular dynamics simulations. The results indicated that the ring thiadiazole and heteroatom of the polar group on the hydrophilic chain were preferentially adsorbed when the inhibitors reacted with metal surface

and the theoretical calculation accorded well with experimental results.