Comparative Corrosion Inhibition Effect of Imidazole Compounds and of Trichodesma indicum (Linn) R. Br. on C38 Steel in 1 M HCl Medium

Table 1

Inhibition studies of organic inhibitors.

Name of the inhibitor	Inhibitor concentration (%)	30°C			40°C			50°C			60°C
		C.R × 101; mmpy	IE (%)	Surface coverage (θ)	C.R × 101; mmpy	IE (%)	Surface coverage (θ)	C.R × 101; mmpy	IE (%)	Surface coverage (θ)	C.R × 101; mmpy	IE (%)	Surface coverage (θ)
Imidazole	0	0.2196	—	—	0.3599	—	—	0.5113	—	—	0.6516	—	—
	2	0.1223	30	0.443	0.0465	87.6	0.8705	0.0471	91.53	0.9078	0.1891	75	0.7097
	2.5	0.1092	39	0.5027	0.0428	89.5	0.8811	0.0443	92.44	0.9134	0.1643	78.6	0.7478
	3	0.0846	48	0.6147	0.0362	90.5	0.8994	0.0358	93.43	0.9299	0.1174	82.2	0.8198
	3.5	0.0621	58.1	0.7172	0.0366	91.3	0.8983	0.0226	95.52	0.9557	0.1049	85	0.839
	4	0.0481	60	0.7809	0.0334	93.6	0.9072	0.0218	96.33	0.9574	0.0721	89.9	0.8893
	4.5	0.0495	52.8	0.7745	0.0525	88.5	0.8539	0.0445	91.33	0.9129	0.1055	86.5	0.9391
	5	0.0526	42.7	0.7604	0.108	79.9	0.8032	0.0811	86.15	0.8414	0.1158	85.1	0.8222
Benzimidazole	2	0.1625	16.3	0.26	0.1421	59.9	0.6051	0.2812	37.7	0.45	0.582	20.8	0.1068
	2.5	0.1502	21.9	0.316	0.1351	62.7	0.6247	0.2359	43.9	0.5386	0.5684	22.1	0.1276
	3	0.148	25	0.326	0.1054	68.8	0.7071	0.2019	54.5	0.6051	0.5502	23.6	0.1556
	3.5	0.1462	37.5	0.334	0.0869	75.5	0.7585	0.1539	69.7	0.699	0.5301	30.1	0.1864
	4	0.1481	41.9	0.325	0.0712	82.9	0.8022	0.1306	78.9	0.7312	0.5166	36.3	0.2072
	4.5	0.1492	38.3	0.342	0.0721	82.4	0.799	0.1527	72.2	0.7012	0.5218	34.5	0.1992
	5	0.1521	31.5	0.3072	0.0765	80.6	0.7874	0.1537	69.6	0.6992	0.5248	33.5	0.1945