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 4

Impedance parameters for the corrosion of mild steel in 1N HCl in the absence and presence of various concentrations of the plant extracts at 30°C.

Name of the plant extract	Conc. of extract (% in v/v)	𝑅𝑡 (Ω cm^2)	𝐶dl (𝜇F/cm^2)	Inhibition efficiency (%)
Blank	—	7.58	285.34	(%)
Adathoda vasica	2.0	126.51	17.01	94.0
	4.0	200.34	10.72	96.2
	6.0	285.23	7.65	97.3
	8.0	255.35	8.44	97.0
	10.0	208.34	10.25	96.4
Eclipta alba	2.0	87.86	24.52	91.4
	4.0	136.49	15.86	94.4
	6.0	207.32	10.45	96.3
	8.0	358.80	6.00	97.9
	10.0	356.80	6.00	97.9
Centella asiatica	2.0	18.32	118.02	58.6
	4.0	22.35	96.61	66.1
	6.0	27.54	78.50	72.5
	8.0	35.12	61.51	78.4
	10.0	54.32	39.88	86.0