International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 09 Issue: 03 | Mar 2022 www.irjet.net p-ISSN: 2395-0072 © 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 536 Review: Eco-Friendly Corrosion Inhibitors on Mild Steel in Acidic Medium Shashirekha K. 1, 2 , Shubrajyotsna Aithal 1* , B.M. Praveen 1* 1 Professor, Department of Chemistry, College of Engineering and Technology, Srinivas University, Mukka, Mangalore, Karnataka, India. 2 Assistant Professor, Department of Chemistry, Yenepoya Institute of Technology, Thodar, Mangalore, Karnataka, India. -------------------------------------------------------------------------***------------------------------------------------------------------------ Abstract - Eco friendly corrosion inhibitors were chosen for this review, and their corrosion inhibition tendency was examined. The inhibitory property of these inhibitors on mild steel (MS) in an acidic environment are being explored. It was determined the rate of corrosion by the applications of chemical and electrochemical systems. Corrosion inhibition rises with inhibition efficiency and decreases with temperature, according to these studies. In all of these papers, on mechanisms of adsorption and thermodynamics were explored. Scanning Electron Microscopic investigations were used to discuss surface morphology. Few academics have recently published theoretical studies such as quantum studies. In this paper, all of the works have been discussed. Key Words: Inhibitors, Electrochemical measurements, Eco Friendly, Weight Loss, Tafel 1. Introduction Technical, economic, environmental, and aesthetic perspective, mild steel corrosion control is critical. In the past, cathodic protection, control activities, metal impurity content reduction, surface treatment techniques, and the integration of appropriate alloys were all used to reduce corrosion. On the other hand, inhibitors among the top effective strategies to hinder corrosion in metals and alloys [1-4]. Corrosion hindrances become one of the most cost- effective and easy method of corrosion prevention in acidic environments [5-7]. These corrosion inhibitors reduce the rate of corrosion, hence minimising the economic costs of corrosive attack on commercial containers, machinery, and surroundings. Because both corrosion inhibitors, natural and inorganic are harmful and expensive, researchers have increasingly focused on developing ecologically acceptable corrosion prevention solutions. Several recent studies have concentrated on mild steel corrosion prevention through the use of green inhibitors in acidic solutions to mimic industrial processes, with promising results [8-10]. Many researchers have looked into the corrosion protection of mild steel against corrosive chloride attack using inorganic oxidants like chromate [11-14], Molybdate [15-18], and Tungstate, polar organic molecules such as oxygen, sulphur, and nitrogen [19], with heterocyclic compounds having functional groups and conjugated double bonds as corrosion inhibitors [19-21]. The interaction of polar functional groups through the adsorbent surface on metal particles is usually believed to constitute the mechanism of inhibition [21]. Polar functional groups are normally considered to behave as response centres in organic compounds. A variety of factors influence the adsorption of an inhibitor on a surface of the metal. These parameters include the metal's nature and surface charge, the adsorption process, the inhibitor's chemical composition, and the type of electrolyte utilised. The use of various aliphatic and aromatic amines, as well as nitrogen-heterocyclic compounds, revealed that their inhibitory action is linked to several factors, including (I) molecule structure, (ii) adsorption type, (iii) charge distribution in the molecule, and (iv) the type of organic-metallic surface interaction. The paper provides a summary of the subject of eco-friendly inhibitors for MS in acid environment. It also gives the insights on adsorption and inhibition tendency of the inhibitors. 2. Corrosion Inhibitors Corrosion inhibitors are chemical substances that prevent metal from corroding when exposed to the environment in modest concentrations where a metal would corrode, reduce, slow, or prevent the metal from corroding. Inhibitors frequently act by adsorbing themselves to the metallic surface and producing a layer to protect it. a. Inhibitors inhibit corrosion by polarization effect on the working electrode. b. Due to polarization, it reduces the movement of metal ions.