Synthesis and Corrosion Inhibition Behavior of New Bis-Benzimidazolyl Borate Derivatives

Using diglyceric acid borate (DGB) as raw material, DGB was subjected to amidation-cyclization reaction with o-phenylenediamine and N-methyl-o-phenylenediamine to synthesize two new corrosion inhibitors, namely bis(2-Benzimidazolyl)ethylene glycol borate (2a) and bis(1-N-methyl-2-benzimidazolyl)ethylene glycol borate (2b). The corrosion inhibition properties of the two compounds on Q235 carbon steel in hydrochloric acid pickling solution were studied by weight loss method, electrochemical method and scanning electron microscope (SEM). The results showed that the two compounds had good corrosion inhibition effect on Q235 carbon steel in 5% HCl pickling solution. When the dosage of these two compounds was 100 mg/L and after 6 h corrosion, the maximum corrosion inhibition rate exceeded 98.1%. In addition, the adsorption laws of the two inhibitors on the carbon steel surface conformed to the Langmiur adsorption isotherm, and the adsorption behaviors were both spontaneous and chemical adsorption processes.