Green approach to corrosion inhibition effect of Vitex negundo leaf extract on aluminum and copper metals in biodiesel and its blend

• B.N. Subedi, K. Amgain, S. Joshi and J. Bhattarai

Central Department of Chemistry, Tribhuvan University, Kathmandu, Nepal

Abstract: The corrosion inhibition effect of Nepalese origin plant of Vitex negundo leaf extract on the passivation behavior of aluminum and copper was studied in pure biodiesel (B100) produced from waste cooking oil and its 10% blend with 90% petrodiesel (B10) at 25±2°C in airtight glass bottle using immersion tests, inhibition efficiency and anodic polarization measurements. The corrosion rate of the aluminum and copper metals was decreased with increasing the concentrations of the methanolic fraction of the plant extract up to 2000 ppm in both the B100 and B10 biofuels. The V. negundo extract showed the maximum corrosion inhibition efficiency of about 83% in both B100 and B10 for aluminum metal and its maximum inhibition efficiency for copper metal was found about 96% and 60% in B100 and B10, respectively. The phenomena of such high corrosion inhibition action of V. negundo plant extract to aluminum and copper metals in both B100 and B10 is mostly explained by the adsorption process of the plant extract on the surface of both metals which obeyed the Langmuir adsorption isotherm. It was found that additions of different concentrations of plant extracts in both B100 and B10 acted as mixed and anodic type corrosion inhibitor for copper and aluminum, respectively, based on the results of immersion and polarization tests. Consequently, it can be said that the V. negundo leaf extract can be used as an efficient and environmentally friendly corrosion inhibitor so as to control the corrosion of copper significantly in pure biodiesel as compared to aluminum in B100 and B10 as well as to copper in B10 at room temperature in airtight condition.

Int. J. Corros. Scale Inhib., 2019, 8, no. 3, 744-759 PDF (1 120 K)
doi: 10.17675/2305-6894-2019-8-3-21

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