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

Table 2

Limiting current values for C-steel dissolution in 8 M H₃PO₄ acid in the absence and presence of natural extracts at several temperatures.

Natural compound	Conc. (ppm)	25°C		35°C		45°C		55°C
			IE%		IE%		IE%		IE%
Marjoram (Origanum majorana)	0.00	0.500		0.560		0.670		0.750
	100	0.224	55.2	0.30	46.43	0.366	45.36	0.49	34.67
	200	0.193	61.4	0.245	56.25	0.302	54.93	0.43	42.67
	300	0.154	69.2	0.194	65.36	0.262	60.90	0.321	57.20
	400	0.122	75.6	0.166	70.36	0.243	63.73	0.283	62.27
	500	0.104	79.2	0.142	74.64	0.203	69.70	0.262	65.07
	800	0.083	83.4	0.122	78.21	0.176	73.73	0.241	67.87
	1200	0.072	85.6	0.105	81.25	0.156	76.72	0.223	70.27
	1500	0.052	89.6	0.088	84.29	0.132	80.30	0.193	74.27
	1800	0.033	93.4	0.065	88.39	0.103	84.63	0.167	77.73
Coriander (Coriandrum sativum) seeds	0.00	0.500		0.560		0.670		0.750
	100	0.275	45.0	0.333	40.54	0.440	34.33	0.525	30.00
	200	0.214	57.2	0.278	50.36	0.365	45.52	0.465	38.00
	300	0.166	66.8	0.223	60.18	0.306	54.33	0.378	49.60
	400	0.135	73.0	0.221	60.54	0.276	58.81	0.322	57.07
	500	0.113	77.4	0.186	66.79	0.245	63.43	0.281	62.53
	800	0.102	79.6	0.162	71.07	0.213	68.21	0.263	64.93
	1200	0.093	81.4	0.143	74.46	0.184	72.54	0.243	67.60
	1500	0.082	83.6	0.125	77.68	0.162	75.82	0.223	70.27
	1800	0.062	87.6	0.096	82.86	0.142	78.81	0.204	72.80
Chamomile (Matricaria recutita)	0.00	0.500		0.560		0.670		0.750
	100	0.325	35.0	0.378	32.50	0.463	30.90	0.543	27.60
	200	0.232	53.6	0.305	45.54	0.375	44.03	0.502	33.07
	300	0.183	63.4	0.265	52.68	0.322	51.94	0.445	40.67
	400	0.156	68.8	0.242	56.79	0.292	56.42	0.402	46.40
	500	0.135	73.0	0.209	62.68	0.262	60.90	0.364	51.47
	800	0.123	75.4	0.189	66.25	0.242	63.88	0.315	58.00
	1200	0.108	78.4	0.165	70.54	0.212	68.36	0.278	62.93
	1500	0.122	75.6	0.176	68.57	0.225	66.42	0.302	59.73
	1800	0.136	72.8	0.206	63.21	0.258	61.49	0.335	55.33
Guava leaves (Psidium guajava L)	0.00	0.500		0.560		0.670		0.750
	100	0.372	25.6	0.405	28.21	0.502	25.07	0.572	23.73
	200	0.335	33.0	0.362	35.68	0.445	33.58	0.543	27.60
	300	0.273	45.4	0.322	42.50	0.387	42.24	0.502	33.07
	400	0.254	49.2	0.296	47.14	0.362	45.97	0.456	39.20
	500	0.186	62.8	0.242	56.79	0.333	50.30	0.425	43.33
	800	0.155	69.0	0.225	59.82	0.306	54.33	0.387	48.40
	1200	0.134	73.2	0.203	63.75	0.283	57.76	0.342	54.40
	1500	0.152	69.6	0.228	59.29	0.318	52.54	0.366	51.20
	1800	0.167	66.6	0.253	54.82	0.345	51.49	0.393	47.60