Adsorption and Charge Transfer Resistance Behavior of Ficus hispida Leaf Extract on Mild Steel Against Acid Attack
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TECHNICAL ARTICLE—PEER-REVIEWED
Adsorption and Charge Transfer Resistance Behavior of Ficus hispida Leaf Extract on Mild Steel Against Acid Attack P. Muthukrishnan . P. Prakash
Submitted: 28 April 2020 / in revised form: 17 August 2020 / Accepted: 31 August 2020 Ó ASM International 2020
Abstract Metallic corrosion is a serious industrial problem due to its impact on economic losses and unavoidable structural damage. In this work, Ficus hispida leaf extract (FHLE) is employed in 1 M H2SO4 as a corrosion control agent on mild steel. FHLE effect on corrosion reduction of mild steel has been studied using non-electrochemical and electrochemical methods. From the experimental results, it is proved that the protection efficiency rises with increase in FHLE concentration and diminishes with increase in temperature. Tafel polarization plots suggest that FHLE prevents corrosion both anodic and cathodic area. The charge transfer resistance increased and the double-layer capacitance diminished when the FHLE concentration increased which is verified by AC impedance data. Various spectroscopic studies have affirmed the presence of a protective film on the electrode surfaces. Keywords Working electrode Acid inhibition Polarization AC impedance SEM
Introduction Corrosion control is one of the most critical tasks in various industrial operations such as etching, descaling, oil well acidification and coiled tubings. Corrosion management decreases production costs, increases plant life and lowers P. Muthukrishnan (&) Department of Chemistry, Faculty of Engineering, Karpagam Academy of Higher Education, Coimbatore 641021, India e-mail: [email protected] P. Prakash Department of Chemistry, Thiagarajar College, Madurai 625009, India
investment pressures. Prevention of accidents such as bridge collapse and equipment breakdown due to corrosion is possible by controlling or reducing corrosion. The easiest and simplest way to avoid corrosion is to prevent the surface of metallic object coming into contact with corrosive environment. Application of proper inhibitors like pyridine [1], insulation materials, painting [2] on the metallic surface helps to achieve this goal. It can even be useful to cover the metal surface using other metals such as Zn and Sn [3]. In the electrochemical method, a sacrificial electrode of another metal (like Zn, Mg, etc.) is provided which corrodes itself but saves the object [4]. The use of inhibitors has been considered as the easiest and most practical of all methods. Many requirements for the use of inhibitors in large scale industries such as inhibitor price, its effectiveness, toxicity and level of ecofriendliness have to be taken into account. In recent years, different kinds of natural and organic products such as herbal extracts, named verdant inhibitors, have had considerable interest in the presence of acidic media as useful and effective inhibitors of metal corrosion [5–7]. The majority of the natural inhibitors examined are nitrogen and oxygen in structure [8, 9]. Ficus hispida is medici
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