Synthesis and Corrosion Inhibition Behavior of New Benzimidazole Derivatives

The intermediate of 1,3-dioxolane-4-carboxylic acid (DIC) was prepared using glycerin from by-product of illegal cooking oil hydrolysis and polyformaldehyde as raw materials. Three target products, 2-(1',3'-dioxolan-4-yl) benzimidazole (OBCI),1-methyl-2-(1',3'-dioxolan-4-yl) benzimidazole (MBCI) and 1-phenyl-2- (1',3'-dioxolan-4-yl) benzimidazole (PBCI) were synthesized by amide-cyclization reaction between DIC and o-phenylenediamine and its derivatives. The inhibition performance of the three compounds to Q235 steel in 5% (mass fraction) HCl solution was studied by immersion testing, electrochemical testing and scanning electron microscopy (SEM). The results show that the corrosion inhibitors had good corrosion inhibition to Q235 steel in 5% HCl solution, and the inhibition efficiency increased with the increase of inhibitor concentration. When the mass concentration of corrosion inhibitors was 100 mg/L, the maximum corrosion rates measured by weitht-loss method were more than 97%. The adsorption of three inhibitors on the surface of Q235 steel followed the Langmuir adsorption isotherm,and the adsorption process was spontaneous chemisorption.