Ekerete Boekom et al./ Elixir Appl. Chem. 142 (2020) 54382-54387 54382 1.0 Introduction The demand for Iron and its alloys in industries is on the increase owing to its superior mechanical strength in comparison with other metals (Strickland, 1923). It is preferred in ship and bridge construction, riveting, bolting, and several others where high mechanical strength is required (Bebon, 2011). However, steel proneness to corrosion is one of the greatest challenges in industries (Solomon et al., 2017). During industrial exercises like metal scale removal and cleaning, acid descaling, oil well acidizing, aggressive acid solutions come in direct contact with metals. These industrial exercises cause corrosion of metals. It is customary that for any industrial process, corrosion inhibitors be added to acid solution before use, to inhibit metal corrosion (Solomon et al., 2018). Organic compounds (those with N, O, S, P and π – electrons in their structure) (Xhanari and Finsgar, 2016) and inorganic compounds (nitrites, nitrates, phosphates and lanthanides) (Umoren and Solomon, 2017a) are the common acid corrosion inhibitors. Organic metal corrosion inhibitor demand stood at 70 %, while that of the inorganic counterpart is remarkably low (Umoren and Solomon, 2017b) due to their negative influence on the ecosystem. This work was designed to examine the inhibition ability of Pyridine. The investigation was done using gravimetric and quantum chemical techniques. N H H H H H Figure 1. Chemical structure of Pyridine (C 5 H 5 N) 2.0 Experimental Details 2.1 Materials and Metal Samples Preparation Pyridine compound used in this experiment was of analytical grade and product of M and B limited, Dagenham, England. All other chemicals were procured from Sigma Aldrich and were used as purchased. The metal sheet obtained from Ken Johnson Engineering Company, Uyo, Nigeria was cut into 5 x 4 cm coupons for gravimetric experiments. The samples were mechanically abraded using different grit of emery papers (#800 – #2000 grade).Thereafter, they were washed with distilled water, degreased with ethanol, rinsed in acetone and dried with warm air (Verma et al., 2017) and then stored over calcium chloride in a desiccator prior to use (Solomon et al., 2018). 2.2 Gravimetric Investigations The specimens were suspended in a reaction vessel containing 100 ml of studied solution (acid solution without and with different concentrations of Pyridine). Before the samples were introduced into the reaction system, the initial weight was recorded. After immersion time in the solution, the specimens were removed, washed with distilled water, then with acetone, and finally dried with warm air (Solomon et al., 2017; Solomon and Umoren, 2016; Verma et al., 2017). The new weight of the samples was recoreded. Weight loss (g) was computed as the difference between the initial and the final weights. Values of corrosion rate (ρ), surface coverage (Ѳ) and inhibition efficiency (%) were computed using weight loss data (Obot et al., 2011). (t) time Immersion x (A) steel mild of Area W) ( loss Weight ) ( rate Corrosion    (1) 1 2 1 - ) ( coverage Surface      (2) Tele: E-mail address: kufman2016@gmail.com © 2020 Elixir All rights reserved ARTICLE INFO Article history: Received: 14 February 2020; Received in revised form: 12 May 2020; Accepted: 22 May 2020; Keywords Corrosion, Pyridine, Mild Steel. Kinetics, Molecular Dynamics and Adsorption Behaviour of Pyridine on Mild Steel in 0.1M HCl Solution Ekerete Boekom 1 , Kufre E. Essien 2 , V. F. Ekpo 1 and Anne Obot 1 1 Department of Chemistry, University of Uyo, P.M.B 1017, Uyo, Akwa Ibom State, Nigeria 2 Department of Chemistry, Akwa Ibom State University, P.M.B. 1167, Ikot Akpaden, Mkpat Enin ABSTRACT The inhibition of the corrosion of mild steel in 0.1 M HCl solution by Pyridine from 303K to 333K at concentrations of 5 x 10 -4 M, 1 x 10 -4 M, 5 x 10 -5 M, 2 x 10 -5 M and 1 x 10 -5 M was studied using gravimetric technique. The maximum inhibition efficiency of 70 % at 5 x 10 -4 M for 333 K was observed. The compound acted as corrosion inhibitor in 0.1 M HCl solution through adsorption on the mild steel surface. The maximum heat of adsorption (Q) was 1.0297 KJ/mol, whereas the average kinetic energy (Ea) was 20.0 KJ/mol. The weight loss data treated kinetically gave a first order type of mechanism. The results elucidated the effects of inhibitor concentration, temperature, dλ – Pλ interaction between the metal surface, the heteroatom of the inhibitor, and the electron charge densities on the heteroatoms of the Pyridine molecule. The adsorption of the inhibitor on the metal surface obeyed Temkin adsorption isotherm. Quantum chemical calculations using Hartree-fock Density Functional Theory by Hamiltonian method was employed with PM3 (NDDO) basic set of minimal valence basis as STO3G Program. © 2020 Elixir All rights reserved. Elixir Appl. Chem. 142 (2020) 54382-54387 Applied Chemistry Available online at www.elixirpublishers.com (Elixir International Journal)