Research Article

Inhibitory Action of Artemisia annua Extracts and Artemisinin on the Corrosion of Mild Steel in H2SO4 Solution

Table 3

Kinetics and activation parameters for mild steel coupons in 5.0 M H2SO4 solutions in the absence and presence of inhibitors (using the gasometric technique).

System Rate of hydrogen evolution 
(cm min−1)
Inhibition efficiency
(%)

(KJmol−1)
Δ *
(KJmol−1)
Δ *
(Jmol−1 K−1)
30°C40°C50°C60°C30°C40°C50°C60°C

5 M H2SO4 (blank)0.0370.0960.1740.31158.9656.32−86.00
0.1 gL−1 EEAA + 5 M H2SO40.0170.0600.1190.25754.5037.7031.7017.2774.8372.19−39.82
0.5 gL−1 EEAA + 5 M H2SO40.0150.0410.0780.14460.4956.9655.2253.7263.3060.66−79.28
1.0 gL−1 EEAA + 5 M H2SO40.0080.0230.0640.12077.9375.7163.4061.2776.5573.91−40.73
2.0 gL−1 EEAA + 5 M H2SO40.0060.0150.0380.08284.7484.4077.9373.6675.5272.88−47.53
4.0 gL−1 EEAA + 5 M H2SO40.0010.0050.0140.03996.7394.9791.8287.3397.1294.4811.34

0.1 gL−1 AEAA + 5 M H2SO40.0140.0370.0900.25662.4060.8448.4117.5980.7878.14−23.05
0.5 gL−1 AEAA + 5 M H2SO40.0110.0320.0820.16868.9466.1852.9146.0675.5872.94−41.17
1.0 gL−1 AEAA + 5 M H2SO40.0070.0280.0700.13279.8470.6859.5457.6780.4977.84−27.76
2.0 gL−1 AEAA + 5 M H2SO40.0050.0180.0470.09086.3881.0573.2070.9681.0378.39−29.39
4.0 gL−1 AEAA + 5 M H2SO40.0020.0080.0340.07194.0191.7380.5877.1099.9197.2725.45

0.1 gL−1 TEAA + 5 M H2SO40.0270.0790.1490.28626.4317.1714.187.9164.9362.29−68.71
0.5 gL−1 TEAA + 5 M H2SO40.0230.0660.1230.26336.2431.4129.3415.3766.2763.63−65.75
1.0 gL−1 TEAA + 5 M H2SO40.0190.0520.1020.20447.6845.8641.1034.2665.3762.73−70.39
2.0 gL−1 TEAA + 5 M H2SO40.0120.0350.0670.14567.5763.6661.2153.3968.5965.95−63.65
4.0 gL−1 TEAA + 5 M H2SO40.0050.0160.0390.07986.1083.6677.7574.6976.6574.01−44.14

20 mgL−1 ATS + 5 M H2SO40.0350.0920.1670.3065.183.983.571.6759.9057.26−83.33
50 mgL−1 ATS + 5 M H2SO40.0320.0870.1590.28612.269.018.537.9160.2357.59−82.80
100 mgL−1 ATS + 5 M H2SO40.0310.0830.1510.27916.3513.1913.2610.2060.7458.10−81.57
200 mgL−1 ATS + 5 M H2SO40.0260.0710.1450.26528.6125.8616.5414.7364.4261.79−70.80
400 mgL−1 ATS + 5 M H2SO40.0200.0540.1250.23344.4143.0427.7225.0668.4665.82−59.73