Plant extract as biodegradable inhibitor for zinc in dilute solution of sulphuric acid

The inhibitive action of the ethanol extract of oil from Picralima nitida leaf, towards acid corrosion of zinc, is tested using weight loss, and thermometry methods. It was found that the extract acted as a good corrosion inhibitor for zinc corrosion in 0.5 M H2SO4 solution. The inhibitive action of the extract was discussed in view of Langmuir adsorption isotherm. It was revealed that the adsorption of the extract on zinc surface is governed by spontaneous process. The inhibition efficiency (IE) increases in line with corresponding increase in extract concentration. The temperature effect of the corrosion inhibition on the IE was studied. Revelation from the studies indicates that the presence of extract increases the activation energy of the corrosion reaction. Furthermore, from the calculated thermodynamic parameters, it was observed that Picralima nitida extract provides a good protection to zinc against pitting corrosion in chloride ion containing solutions.