Asian Journal of Research in Chemistry

R. Saratha ¹

Affiliations
1 Department of Chemistry, Avinashilingam Deemed University for Women, Coimbatore-641043, Tamilnadu, IN

Abstract

Any product that has been developed should undergo various tests for standardization before it is put into use by the customers. Numerous plants have been evaluated/investigated as corrosion inhibitors for mild steel in acid medium. In the present study the corrosion inhibitive nature of the acid extract of Tectona Grandis for mild steel in 1M HCl and 0.5M H₂SO₄ media for standardization of the plant extract was evaluated through gasometric method. The stability and storage condition of the extract was tested using weight loss method. Gasometric method shows decrease in hydrogen gas evaluation with increase in extract concentration showing the inhibitive nature of the extract. The extract in the base HCl was found to be up to 45 days of storage period in room temperature. There is no significant difference in inhibition efficiency exhibited by plant extract stored in room temperature and in refrigerated condition. The mode of inhibition has been explained from the physiochemical constituents present in the extract and FTIR results.

Keywords

Tectona grandis, Corrosion Inhibitor, Weight Loss, Measurement.

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V. G. Vasudha ¹, R. Saratha ²

Affiliations
1 Department of Chemistry, Nirmala College for Women, Coimbatore-18, IN
2 Dept. of Chemistry, Avinashilingam University for Women, Coimbatore-43, Tamilnadu, IN

Abstract

The corrosion inhibition of mild steel in 1N HCl by acid extract of Nyctanthes arbortristis (night jasmine) leaves (NAL) has been studied using weight loss method. The results of the study reveal that NAL extract is a very good environment- friendly corrosion inhibitor for mild steel in acid medium with maximum inhibition efficiency of 90% at 2% v/v concentration. Inhibition efficiency of the extract is found to vary with concentration, temperature and period of immersion. Thermodynamic consideration reveals that adsorption of extract constituents on mild steel surface is spontaneous. Langmuir, Temkin, Freundlich and Flory-Huggins adsorption isotherms are obeyed. Physical adsorption mechanism is proposed for the adsorption of the inhibitor from the trend of variation of inhibition efficiency with temperature and the values of ΔG.

Keywords

Nyctanthes arbortristis Leaves, Corrosion Inhibitor, Mild Steel, HCL Medium.

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S. V. Priya ¹, R. Saratha ²

Affiliations
1 Dept. of Chemistry, Kongu Engineering College, Perundurai-638052, Erode, Tamilnadu, IN
2 Dept. of Chemistry, Avinashilingam University for Women, Coimbatore-641043, Tamilnadu, IN

Abstract

Corrosion inhibition of mild steel in 1 M HCl was investigated in the absence and presence of different concentrations of extract of Crossandra infundibuliformis leaves. Weight loss measurements and electrochemical studies were employed. The corrosion rate of mild steel and the inhibition efficiencies of the extract were calculated. The results obtained show that the extract solution of the plant could serve as an effective inhibitor for the corrosion of mild steel in HCl media. Inhibition was found to increase with increasing concentration of the plant extract. The inhibitive actions of plant extract are discussed on the basis of adsorption of stable complex at the mild steel surface. Theoretical fitting of different isotherms, Langmuir, Temkin, Freundlich, Frumkin, Flory-Huggins and the kinetic thermodynamic model were tested to clarify the nature of adsorption. Polarisation curves revealed that this inhibitor act as a mixed type inhibitor and the inhibition efficiency up to 97.41% can be obtained. The surface analysis study confirms the corrosion of mild steel and its inhibition by the inhibitor.

Keywords

Mild Steel, Corrosion Inhibitors, Adsorption Isotherms, Inhibition Efficiency.

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R. Saratha ¹, P. Thilagavathy ¹, N. Kasthuri ²

Affiliations
1 Department of Chemistry, Avinashilingam University for Women, Coimbatore, Tamilnadu, IN
2 Department of Chemistry, Sengunthar College of Engineering for Women, Tiruchengode, Tamilnadu, IN

Abstract

The leaves of Vitis vinifera has been tried as a green corrosion inhibitor for mild steel in 1 M HCl. Its inhibitive performance was studied using mass loss method and Electrochemical methods namely potentiodynamic polarization and AC impedance method. The performance of the inhibitor at different time periods, different concentrations of the inhibitor and at various temperatures has been studied. The studies revealed that Vitis vinifera act as a good inhibitor in 1M HCl medium and the maximum efficiency was 97.31% at 2.5% v/v concentration in 24 h period and 89.42% at 323K for the same concentration of the inhibitor. Polarization study revealed that the inhibitor is mixed type with predominant anodic polarization. Activation energies of the process in absence and presence of Vitis vinifera were obtained which suggested that physisorption takes place and inhibitor is more active at lower temperatures. The adsorption isotherm models were tried and it was found to obey Langmuir, Freundlich and Temkin models.

Keywords

Vitis vinifera, Weight Loss Method, Polarisation Study, Adsorption Isotherms.

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