Abstract—Optimization of inhibitive effects of leaves extracts of carica papaya (pawpaw) and veroniniaamigdanina (bitter) on corrosion of mild steel within acidic medium was studied by weight loss tmethod using central composite design of response surface methodology for optimization. Atomic Absorption Spectrophotometer was used to study and determine its elemental compositions. The extract was obtained through liquid extraction using ethanol, as well as analyzed to determine phytochemical components and functional groups using American Society of Testing Materials and Fourier Infra red Spectrometer respectively. The effect of process variables such as concentration of inhibitors, time, temperature and concentration of medium on corrosion rate in the acidic (HCl) medium was studied. The result obtained showed that the major composition of the mild steel is iron and the presence of phytochemical components and functional groups made the extracts perform as good inhibitors. It was observed that the corrosion rate decrease while there was an increase in concentration of the inhibitor, time and concentration of the medium and increase with increase in temperature. The optimal conditions are: concentration of inhibitor 16.36mg/100ml, time, 6.55h, temperature 48oC, concentration of medium 2.2M in pawpaw leaf extract inhibited acidic medium; concentration of inhibitor 18.94mg/100ml, time, 5.5h, temperature 48oC, concentration of medium 1.74M in veroniniaamigdanina (bitter) extract inhibited medium; The optimal conditions obtained gave inhibition efficiencies of 88.4% and 96.4% in pawpaw leaf extract and better leaf extract inhibited acid media respectively. It shows that leaves extracts can inhibit corrosion of mild steel in acidic medium.

Index Terms—Carica papaya (pawpaw), veroniniaamigdanina (bitter), HCl, inhibitors, optimization.

Enekwe Chukwudi Benedict is with Department of Intergrated Science Ebonyi State College of Educatioin, IkwoEbonyi State, Nigeria (email: enekwebenedict@yahoo.com).
T. O. Chime is with Chemical Engineering Department, Enugu University of science and Technology, Nigeria.
E. Osoka is with Chemical Engineering Department, Federal University of Technology, Owerr , Imo State, Nigeria.

Cite: Enekwe Chukwudi Benedict, T. O. Chime, E. Osoka, "Optimization and Effect of Leaves Extracts on Corrosion of Mild Steal in Acidic Medium," International Journal of Bioscience, Biochemistry and Bioinformatics vol. 10, no. 2, pp. 117-126, 2020.

Copyright © 2020 by the authors. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).