Construction of eco‐friendly corrosion inhibitor lignin derivative with excellent corrosion‐resistant behavior in hydrochloric acid solution
Chao Gao, Xin Zhao, Keyin Liu, Xinyu Dong, Shoujuan Wang, Fangong Kong
Abstract
Abstract Organic corrosion inhibitors from natural plant resources have received extensive attention in recent years. Herein, an eco‐friendly corrosion inhibitor lignin–(2,3‐epoxypropyl)trimethyl ammonium chloride (EPTAC) was successfully prepared by grafting EPTAC to kraft lignin. The inhibiting efficiency and its inhibition mechanism were investigated using electrochemical methods, adsorption thermodynamics analysis, and molecular dynamic simulation. The results showed that the lignin–EPTAC molecules formed a protective film on iron surface, resulting in an excellent inhibition efficiency of 97.80% at 100 mg/L concentration. The average surface roughness of steel samples was reduced to 26.6 nm from the original 99.3 nm. The adsorption of lignin–EPTAC molecules on the steel surface follows Langmuir adsorption isotherm model and was a physical–chemical process as well as an exothermic process of entropy reduction. This adsorption of lignin–EPTAC was a conjugated system dominated by benzene ring of lignin–EPTAC to form a chemical bond on the steel surface by conjugation, besides a positive interaction between the metal surface and the positively charged N ions in the head group of lignin–EPTAC.