Mechanism of corrosion inhibition of steel in trichloroacetic acid by an alcoholic extract of rosemary

摘要

Plant corrosion inhibitors have advantages over traditional inhibitors, such as being environmentally friendly, abundant in resources, and cost -effective. This study investigates the corrosion inhibition performance of rosemary (Rosmarinus officinalis L.) ethanol extract on steel in a trichloroacetic acid (TCA) solution. A novel inhibitor, ROE, was prepared using ultrasonic extraction, and its corrosion inhibition mechanism on steel in 0.10 mol/L TCA solution was explored through weight loss method, electrochemical methods, surface analysis techniques, and theoretical calculations. The results indicate that at a concentration of 100 mg/L, ROE achieves a corrosion inhibition rate of 96.30% at 20°C. The adsorption of ROE on the steel surface follows the Langmuir isotherm (20 -30 °C ) and the Frumkin isotherm (40 -50 °C ). Electrochemical studies show that ROE acts as a mixed -type inhibitor, with the entire inhibition process controlled by charge transfer, following a "geometric coverage mechanism" accompanied by a "frequency dispersion effect." Surface tests, including AFM, CLSM, and contact angle measurements, indicate that the addition of ROE significantly reduces the corrosion degree and roughness of the steel surface while enhancing its hydrophobicity. Theoretical calculations elucidate the adsorption behavior of ROE on the steel surface and the interactions between ROE and the metal, further confirming that ROE exhibits excellent corrosion inhibition pe rformance by forming an adsorptive film on the steel surface. The research results provide new insights for the high-value utilization of rosemary.