Antimicrobial and corrosion inhibition activity of Schiff base in mild steel of HCl and H2SO4 acidic solutions

Abstract

The purpose of synthesizing two different types of Schiff base compounds, such as 2-[(4-Nitrophenyl)Imino]MethylPhenol (2, 4- NMP) and 2-[4-MethoxyPhenyl)Imino] Methyl}Phenol (2,4-MMP), are to improve the corrosion inhibition efficiency of Mild steel (MS) using acidic solutions of 1M HCl and 0.5M H2SO4 and investigated antimicrobial activity against bacteria gram positive Staphylococcus aureus and gram negative Escherichia coli. The – NO2 and – OCH3 substituent groups effects in the Schiff base azomethine system [– CH=N] have been investigated. The Fourier transform infrared (FTIR) spectral analysis confirms a range of 1728 –1760 cm-1 , the formation of the azomethine system [-CH=N] in synthesized compounds. Besides, the potential of corrosion was investigated studied by electrochemical impedance studies (EIS), which indicated a high semicircle formed because of the high resistance of allowing the moving of electrons through the metal-electrolyte solution, besides acting as a mixed kind of inhibitor. 2,4-MMP has better inhibition behavior than 2,4-NMP. The morphology of mild steel surface was revealed by the scanning electron microscope (SEM). Thermodynamic investigation showed that two synthesized Schiff bases have Langmuir adsorption isotherms with physisorption and chemisorptions mechanisms. Quantum chemical calculations have been investigated by density functional theory (DFT). These studies concludes that 2,4-MMP has a better corrosion efficiency found as 86.1 % compared with the 2,4-NMP found as 84.2% since the electron donating ability of the substituents – OCH3 to the electron rich azomethine system [-CH=N] group. Further synthesized compounds exhibits high activity against Staphylococcus aureus and Escherichia coli due to substituted groups.