Investigation on Two Compounds of O,O’-dithiophosphate Derivatives as Corrosion Inhibitors for Q235 Steel in Hydrochloric Acid Solution

Abstract

In this work, the O,O’-dithiophosphate derivatives of S-4-methylbenzyl-O,O’-di(phenyl) dithiophosphate (Inhi-Ph) and S-4-methyl benzyl-O,O’-di(4-bromophenyl) dithiophosphate (Inhi-BrPh) were synthesized and characterized by elemental analysis, FT-IR, 1H, 13C and 31P NMR. Meanwhile, the corrosion inhibition of Q235 steel in HCl solution by synthesized inhibitors was evaluated by weight loss and electrochemical measurements. Measurement results indicate that the two inhibitors of Inhi-Ph and Inhi-BrPh are mixed-type inhibitor, the inhibition efficiency increase with inhibitor concentration increasing, decrease with HCl concentration and temperature increasing. The adsorption of Inhi-Ph and Inhi-BrPh on Q235 steel surface obeys Langmuir isotherm, which belongs to chemical adsorption.

Keywords

• dithiophosphate
• inhibitor
• electrochemical
• weight loss
• langmuir