The Electropolishing of C-Steel in Orthophosphoric Acid Containing Methanolic Plant Extract

Table 3

Rate constant and half-life time values for mild steel coupons in 8.0 M H₃PO₄ solutions containing different concentrations of methanolic plant extract using the weight loss technique.

Methanolic extract Conc.(ppm)	Marjoram		Coriander		Chamomile		Guava leaves
	k, min^−1	t^1/2	k, min^−1	t^1/2	k, min^−1	t^1/2	k, min^−1	t^1/2
200	0.052	13.32	0.028	24.75	0.014	49.50	0.018	38.50
600	0.047	14.74	0.026	26.65	0.0115	60.26	0.016	43.31
800	0.034	20.38	0.025	27.72	0.006	115.50	0.013	53.30
1200	0.023	30.13	0.023	30.13	0.004	173.25	0.006	115.50
1500	0.011	63.00	0.022	31.50	0.0104	66.63	0.007	99.00
1800	0.008	86.62	0.009	77.00	0.011	63.00	0.009	77.00