Camphor tree bark extract as green corrosion inhibitor of LCS in 0.5 M H₂SO₄ with and without salt effect

Abstract

Abstract This work tested the ethanol extract of camphor tree Cinnamomum camphora bark (CTBEE) as a green corrosion inhibitor of low carbon steel (LCS) in 0.5 M H 2 SO 4 with and without the synergistic effect of 4000 ppm NaCl or 800 ppm of KI. The corrosion protection of LCS was significantly increased in the presence of CTBEE‐KI and CBWE‐NaCl blends compared with CTBEE alone, according to data performed by electrochemical impedance spectroscopy (EIS) and electrochemical polarization (EP) analyses. The formation of a film by the blends blocks the LCS surface area, preventing corrosive gradients from reaching its surface. Inhibition efficiency (IE%) of 81% and 89% were obtained in the presence of 800 ppm CTBEE‐4000 ppm NaCl and CTBEE‐800 ppm KI, respectively, compared with IE of 65% in the presence of 800 ppm CTBEE only. A maximum IE% of 89% and 97% were reached after 72 h of immersion in the presence of CTBEE‐NaCl and CTBEE‐KI, respectively. Potentiodynamic experiments indicate that the blends act as mixed‐type inhibitors. The inhibition efficiency of CTBEE, CTBEE‐KI, and CTBEE‐NaCl remained effectively high during the testing period of immersion time, which proved the excellent stability of CTBEE in the corrosive acidic media.