The inhibitive effect of zinc oxide on the corrosion of aluminum in 2 M HCl

solution was studied using gravimetric analysis. Different concentrations of the ZnO

were varied for their anticorrosion behavior study on the metal. Results showed that

the zinc oxide exhibited very good performance, with inhibition efficiency of up to

89%, at reducing the corrosion of aluminum in the acidic chloride environment

Fajobi, M. A.

Igheghe, Solomon O.

Okeniyi, Joshua Olusegun

Covenant University Repository

IOP Conference Series: Materials Science and EngineeringPAPER • OPEN ACCESSAnticorrosion Behaviour of Zinc Oxide on Aluminum in 2 M ofHydrochloric Acidic SolutionTo cite this article: Solomon O. Igheghe et al 2021 IOP Conf. Ser.: Mater. Sci. Eng. 1107 012054 View the article online for updates and enhancements.This content was downloaded from IP address 165.73.223.225 on 29/06/2023 at 15:54Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributionof this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Published under licence by IOP Publishing LtdInternational Conference on Engineering for Sustainable World (ICESW 2020)IOP Conf. Series: Materials Science and Engineering 1107  (2021) 012054IOP Publishingdoi:10.1088/1757-899X/1107/1/0120541Anticorrosion Behaviour of Zinc Oxide on Aluminum in 2 Mof Hydrochloric Acidic SolutionSolomon O. Igheghe1, Muyiwa A. Fajobi1 Joshua O. Okeniyi1,2,1Department of Mechanical Engineering, Covenant University, Ota, Ogun State, Nigeria.2Department of Mechanical Engineering Science, University of Johannesburg, Johannesburg, South AfricaCorresponding Author; solomon.igheghe@stu.cu.edu.ngAbstract-The inhibitive effect of zinc oxide on the corrosion of aluminum in 2 M HClsolution was studied using gravimetric analysis. Different concentrations of the ZnOwere varied for their anticorrosion behavior study on the metal. Results showed thatthe zinc oxide exhibited very good performance, with inhibition efficiency of up to89%, at reducing the corrosion of aluminum in the acidic chloride environment.Key words: Aluminum; Zinc oxide; corrosion rate; corrosion inhibitor;corrosion inhibition efficiency; gravimetric analysis; Langmuir adsorptionisotherm1. IntroductionDue to its light weight, simple workability, toughness, conductivity and tensile strength, Aluminum is one of the most favored metals in the manufacturing fields, it is very suitable forthe construction of automobiles and aircraft components [1-3]. Aluminum as a metal is veryprone to corrosion, corrosion has a negative effect on metals [4-6]. Corrosion inhibitor whichare chemical compounds has proven to be effective in the protection of metals from corrosion[7-9]. This inhibitor affects the electrochemical reaction by altering the reactive effects of thecorrosive environment on the metallic surface [10,11]. Zinc oxide (ZnO) as an inorganicinhibitor had been used in studies to reduce the effect of corrosion on mild steel [12-13].However, there is paucity of studies on using ZnO on aluminum corrosion in the acidicchloride medium. Therefore, this article focuses on the anticorrosion behavior of zinc oxideon aluminum in 2 M of HCl.2. Experimental2.1 Materials and setupThe solution used for this experiment is 2 M of HCl solution with varying concentration of1% to 5%, in increments of 1%, of ZnO inorganic inhibitor. The weight loss experiment wasconducted for the period of 504hrs with 6 samples of equal sizes of 1cm by 1cm by 0.3cm,while the acidic solution of 2 M of HCl was prepared to 200ml, after being mixed withdistilled H2O, for every 200ml acidic solution an amount of inhibitor was added for makingthe requisite percentage. The control acidic sample had no inhibitor added into the solution.The metallic samples were placed into the acidic environment with varying inhibitorconcentration for a period of 504 hours, and at every 24 hours interval and the gravimetricweight loss value was measured. From the measured weight loss value (W), the mild steelsurface area (A), density of mild steel (D), and the immersion time (T), the corrosion rate (CR)was computed by the formula [14-15]:87.6WCRDAT \* MERGEFORMAT (1)International Conference on Engineering for Sustainable World (ICESW 2020)IOP Conf. Series: Materials Science and Engineering 1107  (2021) 012054IOP Publishingdoi:10.1088/1757-899X/1107/1/0120542From this equation, the corrosion inhibition efficiency, IE(%), calculation proceeds from thecorrosion through the formula [15]:   (% ) 1 0 0con tro l w ith A vocado o ilcon tro lC R C RIEC R    \* MERGEFORMAT (2)3. Result and discussionAnalysis of the gravimetric weight loss, the corrosion rate, inhibitor efficiency and surfacecoverage values were obtained from the research experiment. From the graph in Figure 1 it isrepresented by the plot of result gotten from the gravimetric weight loss experiment, whileFigure 2 shows the estimated corrosion rate from the weight loss of aluminum in 2 M HCLfor the 504 hours of the exposure time for the experiment. From both figures, it is observedthat at 0% the sample had the highest corrosion rate and loss of weight in the acidicenvironment and this is due to the effect of Cl- ions on the metal which speeds up the weightloss. Results of the experiment at 1%, 2%, 3%, 4% and 5% inhibitor concentration, inhibitedthe samples by slowing down the dissolution of the metal in the acidic solution, from theexperiment, the sample at 3% having the highest inhibition concentration percentage from thestudy, indicates an improved form of absorption reaction that slows down the chloride ionsand the passivation on the metallic surface. This then resulted in the weight loss reductionand the corrosion rate reduction having a high inhibitor efficiency.Figure 1: Plots of the gravimetric weight loss of aluminum in HCl in the presence of zincoxideInternational Conference on Engineering for Sustainable World (ICESW 2020)IOP Conf. Series: Materials Science and Engineering 1107  (2021) 012054IOP Publishingdoi:10.1088/1757-899X/1107/1/0120543Figure 2 Plots of the corrosion rate of aluminum in HCl in the presence of zinc oxideThe result of the corrosion from figure 2 that was used for estimating the corrosion inhibitionefficiency which is shown in figure 3. This graph shows the corrosion rate reduction that wasobserved from the experiment with the sample having 3% concentration resulted in corrosioninhibition efficiency of 89.05% from the experiment at the 504 exposure time period.Figure 3: Plots of the corrosion inhibition efficiency of zinc oxide on aluminum in 2 M HClOther concentrations of zinc oxide that were used in the experiment showed, in the overall,a decreasing trends of corrosion inhibition through the 504 hours of experimental period.The exception to this was the increasing trends of corrosion inhibition efficiency from the 2%and 3% zinc oxide test-system. The implication of these could be due to a system of lowadsorption mechanisms on the aluminum surface as the experimental time progresses.However, consistent corrosion-protection of the aluminum material was maintainedthroughout the experimental period by the system having 2% zinc oxide, which is indicativeof the consideration that the low concentration of zinc oxide effectively mitigated mild steelInternational Conference on Engineering for Sustainable World (ICESW 2020)IOP Conf. Series: Materials Science and Engineering 1107  (2021) 012054IOP Publishingdoi:10.1088/1757-899X/1107/1/0120544corrosion in the acidic chloride environment. These modes of results spark interest on thestudy of the adsorption characteristic of the zinc oxide on aluminum metallic surface.The graph of the absorption isotherm study is shown in Figure 4. The Langmuir adsorptionisotherm modeling approach was used for the experiment, from the plot it shows a quasi-linear trends for most of experimental measurement times. From the isotherm model thefollowing estimated parameters were analyzed; adsorption-desorption coefficient Kads, themodel fitting efficiency, R2, the Gibbs free energy of adsorption, ΔGads and the separationfactor, RL.Figure 4: Langmuir adsorption isotherm model of zinc oxide on aluminum in 2 M HClThe graph of the Kads and of the R2 are shown in Figure 5 while the plots of the Gibbs freeenergy, ΔGads (kJ/mol), and of the separation factor, RL, gotten from the modelling analysesare showed in Figure 6. The plotted values in Figure 5 shows that decreasing nagative valuesof the adsorption coefficient, Kads, as well as an excellent fitting models by the Langmuiradsorption isotherm to the aluminum corrosion data, via the R2 that decreased from 98.54 to87.73 and predominantly increased again to 89.059 at the 504th hourInternational Conference on Engineering for Sustainable World (ICESW 2020)IOP Conf. Series: Materials Science and Engineering 1107  (2021) 012054IOP Publishingdoi:10.1088/1757-899X/1107/1/0120545Figure 5: Langmuir adsorption isotherm model of zinc oxide on aluminum in 2 M HClFigure 6: Langmuir adsorption isotherm model of zinc oxide on aluminum in 2 M HClAlso, the Gibbs free energy plots in Figure 6 showed that negative values, ranging from -20.00 kJ/mol to the more negative value of -29.25 kJ/mol were estimated for this parameter,which indicates spontaneity of the adsorption process by the zinc oxide on the aluminum.These results showed that the prevalent mechanism of zinc oxide adsorption on mild steel isphysisorption, due to the ΔGads that were valued at more negative vaues -20 kJ/mol, butwhich could be said to exhibit some degrees of chemisorption due to the observed decreasingtrend towards -30 kJ/mol. Also, the values of the separation factor, RL, that was in the range 0< RL < -2, throughout the experimental period as shown in Figure 6, indicate favourableadsorption by zinc oxide on the aluminum metal.International Conference on Engineering for Sustainable World (ICESW 2020)IOP Conf. Series: Materials Science and Engineering 1107  (2021) 012054IOP Publishingdoi:10.1088/1757-899X/1107/1/01205464. ConclusionThe corrosion resistance of aluminum in Zinc oxide inorganic inhibitor was effectivelyenhanced in 2M dilute HCl solution. The inhibitor performed excellently with strongadsorption on the surface of the aluminum with optimal inhibition efficiency of 89% therebypassivating the aluminum samples to reduce the active sites of electrochemical reactionoccurring on the samples.AcknowledgementsAuthors wish to acknowledge publication funding support for the work being reported in thispaper by Covenant University Centre for Research Innovation and Discovery, CUCRID,Covenant University, Ota, Nigeria.Reference[1] Godfrey, H., Hayes, M., Anderson, D., Rawlinson, S., Borwick, J., & Clifford, J.(2019). Corrosion of 1050, 1085, and 5083 grade aluminium in the pore water of aGGBS/CEM I grout up to 777 d. Journal of Nuclear Materials, 515, 257–266.[2] David Burleigh, T. (2003). Corrosion of Aluminum and Its Alloys. Handbook ofAluminum, (April 2003).[3] Elayaperumal, K., & Raja, V. S. (2015a). Corrosion Failures. Corrosion Failures.[4] Okeniyi, J. O., Okeniyi, E.T. and Owoeye, T. F. (2016). 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Anticorrosion Behaviour of Zinc Oxide on Aluminum in 2 M

of Hydrochloric Acidic Solution

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Anticorrosion Behaviour of Zinc Oxide on Aluminum in 2 M of Hydrochloric Acidic Solution

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