Camphor Tree Bark Extract As Green Corrosion Inhibitor of LCS in 0.5 M H2SO4 with and Without Salt Effect

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 H2SO4 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.