4. The Inhibitive Effect of Ziziphus JUJUBA Leaves Extract on The Alkaline Corrosion of Aluminium
Inhibition of corrosion of aluminium in 1N NaOH by leaves extract of Ziziphus jujuba (ZJL) was studied using chemical and electrochemical techniques. It was found that the leaves of Ziziphus jujubainhibits the base induced corrosion of aluminium.The inhibition efficiency increased with increase in concentration of ZJL extract and reached the maximum of 76.4%,that decreases with rise in temperature.The inhibition action of ZJL is discussed in view of Langmuir adsorption isotherm.It has been observed that the adsorption of the extract on aluminium surface is a spontaneous process. Polarization measurements showed that ZJL extract acts as mixed typeinhibitor. The surface morphology of aluminium in the absence and presence of ZJL extract in 1N NaOH solution, was studied using scanning electron microscopy. Results obtained from chemical and electrochemical techniques were in good agreement.Thermodynamic parameters such as activation energy and free energy of adsorption were also calculated to explain the inhibition mechanism. The plant extract provides a good protection to aluminium corrosion.
Keywords: Aluminium corrosion; Corrosion inhibitors; Ziziphus jujuba leaves extract; Langmuir adsorption isotherm; Mixed type inhibitor
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