Solvent-free microwave assisted synthesis and corrosion inhibition study of a series of hydrazones derived from thiophene derivatives: Experimental, surface and theoretical study

초록

A series of thiophene hydrazones namely acetyl thiophene benzohydrazide (ATBH), acetyl thiophene amino benzohydrazide (ATABH), propanoyl thiophene benzohydrazide (PTBH) and propanoyl thiophene amino benzohydrazide (PTABH) were synthesized by conventional as well as by energy efficient microwave irradiation exposure and investigated their potential to mitigate corrosion of mild steel in 0.5 M H2SO4 medium. The spectral and elemental analyses including FTIR, H-1 NMR, and CHN analysis were used to characterize synthesized hydrazones. The corrosion inhibition potential of the synthesized compounds was investigated by weight loss and several well known analytical tools such as open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). Metal corrodes by charge transfer mechanism across the interface of metal and acid solution and was found that addition of all the inhibitors to the add solution reduced the corrosion rate appreciably. The inhibitor molecule showed a strong affinity for metal surface and adsorbed on its surface to offer resistance to flow of charge transfer across the interface of mild steel and acid solution. Langmuir adsorption isotherm was followed by adsorption of all the tested compounds. The thin films resulted due to adsorption of compounds on the metal surface were demonstrated by scanning electron microscope-energy dispersive X-ray (SEM-EDX), FTIR and X-ray photoelectron spectroscopy (XPS). Atomic force microscopy of mild steel surface was performed to examine the effect of inhibitors on its surface property. The contact angle measurement was also performed to examine the wettability of mild steel surface towards add solutions. The experimental findings agreed well with the theoretical results performed by density functional theory (DFT). The interaction of inhibitors with mild steel, Fe (110) was investigated by MD simulations. (C) 2019 Elsevier B.V. All rights reserved.

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