Corrosion inhibition of mild steel in 1 M hydrochloric acid by 2,5-bis(2-aminophenyl)-1,3,4-oxadiazole

The inhibition effect of a new class of organic inhibitors (e.g., 2,5-bis(2 -aminophenyl)-1,3,4-oxadiazole [2-APOX]) on the corrosion of mild steel in molar hydrochloric acid (HCl) was investigated. The inhibitor was synthesiz ed and its inhibiting action on the corrosion was studied through weight lo ss and various electrochemical techniques. Potentiodynamic polarization stu dies clearly revealed the fact that 2-APOX is a mixed-type inhibitor. Chang es in impedance parameters (charge-transfer resistance [R-t] and double-lay er capacitance [C-dl]) were indicative of adsorption of 2-APOX on the metal surface, leading to the formation of a protective film that grew with incr easing exposure time. The 2-APOX appeared to function through the general a dsorption mode following the Langmuir adsorption isotherm model. Effect of temperature on the corrosion behavior of mild steel in 1 M HCl with additio n of 80 mg/L of 2-APOX was studied in the temperature range from 25 degrees C to 60 degrees C, The associated activation corrosion and free adsorption energies were determined, This inhibitor is considered a noncytotoxic subs tance.