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

• Published in: Journal of molecular liquids Vol. 283; pp. 788 - 803
• Main Authors: Singh, A.K., Thakur, S., Pani, B., Chugh, B., Lgaz, H., Chung, Ill-Min, Chaubey, P., Pandey, A.K., Singh, J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2019
• Subjects: Acid corrosion; EIS; Energy efficient synthesis; Miller indices; SEM-EDX; X-ray photoelectron spectroscopy; SEM-EDX; Energy efficient synthesis; Acid corrosion; X-ray photoelectron spectroscopy; EIS; Miller indices
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2019.03.126

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, 1H 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 acid 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 acid 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. •All the thiophene based hydrazones were synthesized by microwave assisted method.•Microwave-assisted solvent free synthesis was found economical and energy efficient.•These inhibitors acted as mixed type but predominantly cathodic inhibitor.•Their adsorption was investigated by XPS and IR spectrum.•All the experimental results showed good agreement with DFT and MD study.