Anti-Corrosive Potentials of 1,2,4-Triazole-5-thiones For Mild Steel 1030 in Acidic Environment
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HYSICOCHEMICAL PROBLEMS OF MATERIALS PROTECTION
Anti-Corrosive Potentials of 1,2,4-Triazole-5-thiones for Mild Steel 1030 in Acidic Environment Nasima Arshada, *, Muhammad Akrama, Fouzia Altafb, and Azra Yaqubc aDepartment
bPakistan
of Chemistry, Allama Iqbal Open University, Islamabad, 44000 Pakistan Council of Research in Water Resources, Ministry of Science and Technology Islamabad, Pakistan c Chemistry Division, PINSTECH, Nilore, Islamabad, Pakistan *e-mail: [email protected] Received August 29, 2019; revised March 15, 2020; accepted March 17, 2020
Abstract—Corrosion is a phenomenon that directly related to the environment. The surface protection by potential inhibitors is one of the possible solutions to combat metal/or metallic alloy corrosion. Here, we are reporting two 1,2,4-triazole-5-thione derivatives – 4-amino-3-(N-phthallimidomethyl)-1,2,4-triazole-5thione (Tz-1) and 3-(N-phthalimidomethyl)-4-(4-pyridine)amino-1,2,4-triazole-5-thione (Tz-2) for corrosion inhibition performance on mild steel (MS) surface in 1 M HCl. Electrochemical experiments were carried for potentiodynamic polarization (PDP) and impedance spectroscopic (EIS) measurements of corroded MS surface before and after the addition of compound’s concentrations. Variations in the PDP responses and in the relevant parameters after compound’s addition confirmed that both Tz-1 and Tz-2 are mixed-type inhibitors. An increase in the diameter of a capacitive loop with inhibitor’s concentration in EIS studies revealed the formation of an adsorbed layer on the MS surface; hence protecting corrosion reaction by controlling the charge transfer process. The data obtained from PDP and EIS were reasonably in good agreement. The IE% (inhibition efficiency) of both Tz compounds showed increasing trend as inhibitor’s concentration was increased and the values were evaluated up to 95% and 94%, respectively, at their optimal concentration of 2.5 × 10−4 M. Adsorption studies using the Langmuir model further confirmed the involvement of physisorption process on MS in the presence of both compounds. Theoretical DFT (density functional theory) analysis results were supportive to comparatively more inhibitory efficiency of Tz-1. SEM (scanning electron microscopic) studies indicated more resistive behavior of MS surface for corrosion in the presence of Tz-1. Keywords: 1,2,4-triazol-5-thione, MS surface, PDP & EIS, DFT, SEM DOI: 10.1134/S207020512004005X
1. INTRODUCTION The utility of metals and metallic alloys is widespread in various industries and in every field of life due to their constructive properties like high electrical and thermal conductivity, high formability, mechanical workability and excellent strength [1]. The major destruction in metals/metallic alloys usually arises due to corrosion that obviously decreases their efficiency [2]. Corrosion is a continuous threat not only for industries but also for public safety. Extensive repairment and replacement of the failure or corroded parts of the materials used in the construction of ships, vehicles,
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