Browsing by Author "Gopal Ji"

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Donor-π-Acceptor-Type Configured, Dimethylamino-Based Organic Push-Pull Chromophores for Effective Reduction of Mild Steel Corrosion Loss in 1 M HCl
(American Chemical Society, 2018) Madhu Tiwari; Vinod Kumar Gupta; Ram Adhar Singh; Gopal Ji; Rajiv Prakash
In this work, donor-π-acceptor-type four crystalline compounds have been tested for the first time to restrict the corrosion of mild steel in 1 M HCl. The details of the compounds are: C1, 4-N,N-dimethylamino-β-nitrostyrene; C2, 2-(4-(dimethylamino) benzylidene)malononitrile; C3, ethyl 2-cyano-3-(4-(dimethylamino) phenyl)acrylate; and C4, methyl 2-cyano-3-(4-(dimethylamino)phenyl)acrylate. The corrosion inhibition potentials of the compounds have been primarily investigated by electrochemical techniques, such as linear polarization resistance, Tafel polarization curves, and electrochemical impedance spectroscopy. The secondary investigation is performed by scanning electron microscopy, fluorescence surface imaging, spectroscopic techniques (UV-visible and Fourier transform infrared spectroscopy), and X-ray diffraction patterns. The results disclosed that 50 mg L-1 of the compounds (1-4) in 1 M HCl provided the maximum inhibition efficiency as 93% (1), 88% (2), 82% (3), and 86% (4). The function of the compounds as corrosion inhibitors is explained with equilibrium corrosion potential, adsorption isotherms, and the frontier molecular orbital energies of the compounds (EHOMO and ELUMO) estimated by cyclic voltammetry curves and UV-visible spectra. © 2018 American Chemical Society.
Electrochemical investigation of Irbesartan drug molecules as an inhibitor of mild steel corrosion in 1 M HCl and 0.5 M H2SO4 solutions
(Elsevier B.V., 2017) Monika Srivastava; Preeti Tiwari; Sanjay Kumar Srivastava; Rajiv Prakash; Gopal Ji
Inhibition effects of Irbesartan drug on mild steel corrosion in 1 M HCl and 0.5 M H2SO4 solutions have been investigated by open circuit potential (OCP) curves, Tafel polarization curves, linear polarization curves and electrochemical impedance spectroscopy (EIS) along with cyclic voltammetry (CV), UV–visible, FTIR and NMR spectroscopy techniques. Maximum corrosion inhibition of 94% and 83% have been achieved at 300 mg L− 1 Irbesartan concentration in 1 M HCl and 0.5 M H2SO4, respectively. Adsorption of Irbesartan on mild steel surface is studied by SEM and various isotherm models, which follows Langmuir isotherm. The effects of rise in temperature and acid concentration on the corrosion behavior of mild steel in both acid solutions are also studied by weight loss method. Corrosion inhibition by Irbesartan is explained on the basis of experimental results as well as frontier molecular orbitals estimated by CV and UV–visible spectroscopic measurements. © 2017 Elsevier B.V.
Low cost aqueous extract of Pisum sativum peels for inhibition of mild steel corrosion
(Elsevier B.V., 2018) Monika Srivastava; Preeti Tiwari; S.K. Srivastava; Ashish Kumar; Gopal Ji; Rajiv Prakash
This work investigates the potential of Pisum sativum (green pea) peels for the inhibition of mild steel corrosion in hydrochloric acid (HCl) at varied temperatures. Various techniques, like weight loss measurements, tafel polarization curves, electrochemical impedance spectroscopy (EIS), UV–visible and Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and atomic force microscopy (AFM), have been used to test the inhibition properties of aqueous Pisum sativum peels extract (APSPE) in acid media. The results indicate that APSPE effectively inhibits the corrosion of mild steel by covering the active corrosion sites on the mild steel surface and thus lowers the electrochemical activity of the surface exposed in HCl solution. The maximum inhibition efficiencies of APSPE system at 400 mg L−1 concentration in 1 M HCl are reported as: 91%, weight loss; 87% polarization curves; and 90% by EIS. The corrosion behavior of mild steel in presence of APSPE has also been investigated in the range of 1 to 4 M HCl at room temperature as well as at varied temperatures (303−333 K) in 1 M HCl. The process of mild steel corrosion inhibition in HCl by APSPE has been explained by ion chromatography analysis and DFT calculations. © 2018