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

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 0.1 M 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 to 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 to reach its surface. Inhibition efficiency (IE%) of 81 and 89% were obtained in the presence of 800 ppm CTBEE-0.1 M NaCl and CTBEE-800 ppm KI, respectively, compared to IE of 65% in the presence of 800 ppm CTBEE only. A maximum IE% of 89 and 97% were reached after 72 hours of immersion in the presence of CTBEE-NaCl and CTBEE-KI, respectively. Potentiodynamic experiments indicate that the blends act as mixed-type inhibitors. Inhibition efficiency of CTBEE, CTBEE-KI and CTBEE-NaCl remained effectively high with testing period of immersion time which proved the good stability of CTBEE in the corrosive acidic media.