Vol. 3, Issue 1 (2019)
Evaluation of plant extract as anti-corrosion for zinc in 1.0 m HCL. Using response surface methodology
Author(s): Ezeugo JO, Ikebudu KO
Abstract: Optimization of inhibitive action of the ethanol extract of oil from Picralima nitida seed, towards acid corrosion of zinc is tested using weight loss, and thermometric methods. It was found that the extract acted as a good corrosion inhibitor for zinc corrosion in 1.0 M HCl solution. The inhibition 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 indicated that the presence of extract increases the activation energy of the corrosion reaction. Furthermore, from the calculated thermodynamic parameters, it was observed that the extract provides a good protection to zinc against pitting corrosion in chloride ion containing solutions. FT-IR analysis of picralima nitida seed extract on pure and corroded product showed a gradual shift of the corrosion mechanism as 3952.4cm-1 stretch bond of aliphatic and aromatic peak shifted to 3940.82cm-1strong and broad O-H alcohol. In much same way,2829.14cm-1 C≡C stretch bond of aldehyde shifted to 2643.86cm-1O-H,stretch bond of carboxylic acid at a strong and very broad intensity. An optimal inhibition efficiency IE (%) of 86.78 was obtained at optimum inhibitor concentration of 1.2gl-1, optimum temperature and time of 313k and 8 hrs respectively.