The Inhibitory Action of the Extracts of Adathoda vasica, Eclipta alba, and Centella asiatica on the Corrosion of Mild Steel in Hydrochloric Acid Medium: A Comparative Study

Table 2

Effect of immersion time on percentage inhibition efficiency of mild steel in 1N HCl at 30°C in the presence of optimum concentration of the plant extracts.

Name of the plant extract with optimum conc.	Inhibition efficiency (%)
	Time (h)
	3	6	9	12	15	18	21	24
6% v/v of Adathoda vasica	99.0	98.2	96.6	96.2	95.5	94.4	93.6	92.7
8% v/v of Eclipta alba	99.6	98.5	98.0	97.3	96.5	96.0	95.3	94.8
10% v/v of Centella asiatica	85.3	84.8	84.3	78.6	71.4	70.8	68.3	67.1