Protecting iron from corrosion using organic acids and calculating corrosion coefficients

Abstract

This research studied the protection of iron from corrosion in a hydrochloric acid solution (0.5M) using salicylic acid and succinic acid based on the weight loss method. Organic acid extracts were chosen as a corrosion inhibitor to coat and protect iron samples because these acids are abundant, inexpensive, and readily available, in addition to having good antioxidant properties. Weight loss measurements showed that salicylic acid exhibited higher inhibition than succinic acid; therefore, its inhibition efficiency was investigated at temperatures ranging from 303 to 340 K. Increasing the concentration of the organic acid was found to reduce iron corrosion and increase inhibition efficiency. The kinetic parameters ,activation energy, enthalpy, and entropy ,were calculated. The optimal conditions for the aforementioned extracts were determined as (T=30C, time 72=hours, concentration = 0.01M). The studied iron samples were treated with the organic acid extract under the same conditions previously determined. The effect of the inhibitor type and concentration, the effect of temperature, and the change in the rate of corrosion of these samples were studied, and corrosion coefficients such as activation energy, enthalpy, and entropy were calculated. The results for the corrosion rate of samples treated with the extract were compared with those of untreated samples. The corrosion rate values ​​before and after treatment were as follows: The corrosion rate of the iron samples (before treatment with the extract) during a 72-hour immersion period was 0.325 mg/cm²·H. After treatment with salicylic acid, it was 0.146 mg/cm²·H, and after treatment with succinic acid, it was 0.284 mg/cm²·H. The inhibition efficiency was 73% for salicylic acid and 57% for succinic acid.