Thermodynamic and Optimization Studies of Castor Leaf Extract as Corrosion Inhibitor on Stainless Steel (301)


  • Akindele Oyetunde Okewale Department of Chemical Engineering, Federal University of Petroleum Resources, Effurun
  • Ayodeji Temitope Adebayo Department of Chemical Engineering, Federal University of Petroleum Resources, Effurun


Weight loss, Activation parameters, Adsorption, Optimization, Stainless steel, Castor leaf


Inhibition of stainless steel corrosion in acidic medium with castor leaf extract was studied using the Gravimetric measurement. The mechanisms of inhibition, influence of temperature on inhibition efficiency and weight loss were determined for temperature range 40 oC – 80 oC at 7 hours immersion time. An increased in temperature showed a decreased in the inhibition efficiency of the castor leaf extract which resulted to increase in weight loss of the stainless steel. The value of rate constant for the corrosion process ranges from 0.333 – 1.225 , this is seen to be directly relative to the inhibitor concentrations.  Activation energy, enthalpy of activation, and entropy values ranges from 74.000 - 136.377 kJ/mol, 71.820 – 133.620 kJ/mol, and 9.860 – 178.110 J/molK respectively. Rise in activation energy with inhibitor concentration confirmed physisorption adsorption mechanism for stainless steel surface corrosion. In order to obtain the optimum weight loss, optimization of the process variables was carried out using the Box – Behnken Design plan and desirability function of response surface methodology (RSM). Four parameters were varied viz; time of immersion, HCl concentration, inhibitor’s concentration, and temperature alongside their effects on weight loss of the stainless steel were verified. The optimal conditions predicted from the second order quadratic model were time (9.10 hours), HCl concentration (3.97 M), concentration of inhibitor (240.90 ppm), and temperature (78.67 oC) with 2.978 g as the weight loss. Statistically, the results showed that 95.03% of the variation in total weight loss of stainless steel can be connected to the experimental variables examined.


AbdEl-hameed, R. S., (2011). Aminolysis of Polyethylene terephthalate Waste as Corrosion Inhibitor for Carbon Steel in HCl Corrosive medium, Advances in Applied Science Research, 2(3):483 – 499.

Abeng, F. E.; V. D. Idim and P. J. Nna. (2017). Kinetics and thermodynamnic study of corrosion inhibitor of mild steel using methanolic extract, World news of natural sciences, 10:26 – 38.

Ambrish, S.; E. E. Ebenso and M. A. Quraishi. (2012). Corrosion inhibitor of carbon steel in HCl solution by some plant extracts, International Journal of Corrosion, 2012: 1-20, DOI 10.1155/201/897430.

Andreani, S.; M. Znini L. Paolini J. Majidi B. Hammouti J. Costa1 and A. Muselli. (2016). Study of corrosion inhibition for mild steel in hydrochloric acid solution by limbarda crithmoides (l.) Essential oil of corsica, Journal of Mater. Environ. Sci. 7 (1):187-195.

Ashassi-Sorkhabi, H.; S. Mirzaee T. Rostamikia and R. Bagheri. (2015). Pomegranate (Punica granatum) Peel Extract as a Green Corrosion Inhibitor for Mild Steel in Hydrochloric Acid Solution, International Journal of Corrosion, 2015: 1-7,

Bas, D. and Boyaci, I. H. (2007). Modeling and optimization 1: Usability of response surface methodology, Journal of Food Engineering, 78:836 – 845.

Callister, W. D. (1997). Material science and engineering, 4th edition, John Wiley and Sons Inc., New York, USA.

Eddy, N. O; P. A. Ekwumemgbo and A. P. Mamza. (2009). Ethanol extract of terminalia catappa as green inhibitor for the corrosion of Carbon steel in acidic medium. Green Chemistry letters and reviews, 2:223-231.

Ekanem, U. F; S. A. Umoren I. I. Udousoro and A. P. Udoh. (2010). Inhibition of mild steel corrosion in HCl using pineapple leaves extract, Journal of Materials and Science, 45:5558 – 5566.

Fontana, M. G. and Green, N. D. (1978). Corrosion engineering, 2nd Ed., McGraw – Hill Publication, USA, 460.

Ijuo, G. A.; H. F. Chahul and I. S. Eneji. (2016). Corrosion inhibition and adsorption behaviour of Lonchocarpus laxiflorus extract on mild steel in hydrochloric acid, Ew. J. Chem. Kine. 1:21-30.

Kuye, S. I. and Olanipekun O. O. (2018). Investigation of corrosion inhibition of mild steel in 0.5 M HCl with Azadiracthaindica and Spondiamombin, Journal of science and technology, 4:42 – 47.

Larouj, M.; K. Ourrak M. M. El Rabet H. Zarrok H. Serrar and M. Boudalia. (2017). Thermodynamic study of corrosion inhibition of carbon steel in acidic solution by new pyrimidothiazine derivative. Journal of Materials and environmental science, 11:3921-3931.

Li, W.; Z. Wang; Y. S. Sun L. Chen. L. K. Han and Y. N. Zheng. (2011). Application of response surface methodology to optimize ultrasonic – assisted extraction of four chromones in radix saposhnikoviae, phytochem. Anal., 22: 313 – 321.

Montgomery, D. C.; (2001). Design and analysis of experiments, 5th edition, John Wiley and Sons, New York, USA.

Mouheddin, T. A.; S. A. Umoren B. O. Ime and A. A. Shaikh. (2018). Isoxazolidine derivatives as corrosion inhibitors for low carbon steel in HCl solution: experimental, theoretical and effect of KI studies, Royal Society of Chemistry, 8:1764 – 1776.

Mourya, P.; S. Banerjee and M. M. Singh. (2014). Corrosion inhibition of mild steel in acidic solution by Tagetes erecta (Marigold flower) extract as a green inhibitor, Corrosion Science, 85: 352 – 363.

Obot, I. B. and Obi-Egbedi, N. O. (2010). An interesting and efficient green corrosion Inhibitor for aluminium from extracts of Chlomolaenaodorata L in acidic solution, Journal of Applied Electrochemistry, 40(11):1977–1983.

Ogoke, E. C.; S. A. Odoemelam B. I. Ita and N. O. Eddy. (2009). Adsorption and inhibitive properties of clarithromycin for the corrosion of zinc in 0.01 to 0.05M H2SO4, Port, Electrochim. Acta, 27:713 – 724.

Oguzie, E. E.; C. O. Akalezi and C. K. Enenebaku. (2013). Inhibition of acid corrosion of mild steel by biomass extract from the petersianthus macrocarpus plant. J. Mater. Environ. Sci. 4(2): 217 – 226.

Okafor, P. C.; M. E. Ikpi I. E. Uwah E. E. Ebenso U. J. Ekpe and S. A. Umoren. (2008). Inhibitory action of Phyllanthus amarus extracts on the corrosion of mild steel in acidic media, Corros. Sci., 50: 2310.

Okewale, A. O.; P. K. Igbokwe and O. A. Adesina. (2015). Optimization of the adsorptive dehydration of ethanol –water system. Chemical and Process Engineering Research, 39:27 – 37.

Omnia S. S.; A. K. Lobna and A. Adel. (2017). Green Corrosion Inhibitors, Past, Present, and Future, DOI: 10.5772/intechopen.72753.

Rodrigues, R. C.; W. R. Kenealy D. Dietrich and T. W. Jeffries. (2012). Response surface methodology (RSM) to evaluate effects on corn stover in recovering xylose by DEO hydrolysis. Bioresource Technol., 108:134 – 139.

Umoren, S. A.; O. Ogbobe E. E. Ebenso and U. J. Ekpe. (2006). Effect of halide ions on well steels using organic inhibitors – A review: Journal of Material Environment Science, 3(5): 284-292.

Uwah, I. E.; P. C. Okafor and V. E. Ebiekpe. (2013). Inhibitive action of ethanol extracts from Nauclea latifolia on the corrosion of mild steel in H2SO4 solutions and their adsorption characteristics, Arabian Journal of Chemistry, 6(3):285 – 293.

Vimala, R. J.; A. LeemaRose and S. Raja. (2011). Cassia auriculata extract as corrosion inhibitor for mild steel in acid medium. International Journal of Chem Tech Research, 3(4): 1791-1801.

Yetri, Y.; E. Emriadi; N. Jamarun and G. Gunawarman. (2015). Corrosion Inhibitor of Mild Steel by Polar Extract of Theobroma cacao Peels in Hydrochloric Acid Solution, Asian Journal of Chemistry, 27(3): 875 – 881.

Zarrouk, A.; B. Hammouti H. Zarrok S. S. Al-Deyab and A. Messali. (2011). Temperature effect, Activation Energies and Thermodynamic Adsorption Studies of L-Cysteine Methyl Ester Hydrochloride as copper corrosion inhibitor in nitric acid 2M, International Journal of Electrochemical Science, 6:6261 – 6274.

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