Inhibitive Action of Water Extract of Spondias Mombin on Corrosion of Low Carbon Steel in 0.5 M Sulphuric Acid

Abstract

Corrosion inhibition of water extract of Spondias mombin on low carbon steel in 0.5 M sulphuric acid was investigated in this paper. Fresh leaves, fruits and bark of this plant, washed properly, ground separately using small amount of distilled water to extract the juice at a ratio of 500 ml (distilled water) to 1 kilogram of plant were used for this experiment. Corrosion inhibitors of 0.4 g/ml, 1 g/ml and 2 g/ml were made from the filterate. Low carbon steel coupons suspended with twine inside 250 ml container of 0.5 M sulphuric acid in the presence of different concentrations of the extracts at room temperature for 35 days. The coupons were retrieved at 7 days interval, and the initial and final weights were recorded. Inhibition efficiency for the leaves extract increased with concentration and got to its peak on the 7th day, that of the fruits extract initially increased with concentration until 1 g/ml after which there was a decline, its highest value was also recorded on the 7th day. The best inhibition efficiencies (in the range of 76.32% to 83.21%) for Spondias mombin water extract were observed in 0.4 g/ml bark extract throughout the days of the experiment, the highest being recorded on the14th day. It can be concluded that Spondias mombin water extract is a good corrosion inhibitor of low carbon steel in 0.5 M sulphuric acid at room temperature, with the best being the bark extract which inhibited for up to 35 days.

Inhibitory action of Spondias mombin leaves extracts on corrosion of mild steel in 1M HCl

“…Table 3 shows that both extracts addition lowers the i_corr values, which implies that the extracts lowers the corrosion rate of the steel. However, it was observed that the ethanol extract causes the greater reduction in i_corr which confirms that the ethanol extract performs better than the water extract (Obi-Egbedi et al, 2014;Sidikat et al, 2018;Al-Otaibi et al, 2014).…”

“…From Figure 4, it can be seen that the adsorption of the Spondias mombin extract followed the Langmuir and Freundlich isotherms. This indicates that the extract components adsorbed as single layer on very roughened steel surface during the corrosion (Sidikat et al, 2018;Obi-Egbedi et al, 2012). This mode of adsorption could easily detach.…”

“…Also known as yellow mombin or hug plum; a specie of tree and flowering plant in the family Anacardiaceae. Previously, Spondias mombin extracts have been reported for corrosion inhibition of aluminium (Al) in 0.5 M H2SO4 (Obi-Egbedi et al, 2012), stainless steel in 3.5 % NaCl (Oguike and Oni, 2019), mild steel in H2SO4 (Sidikat et al, 2018) and HCl (Magu et al, 2017). However, these works only focused on extracts of single solvents.…”