Semnan University Press Applied Chemistry Today 2981-2437 18 66 2023 03 21 Preparation of new Schiff bases based on thiosemicarbazide and evaluation of their inhibitory properties on corrosion of carbon steel in acidic environment Preparation of new Schiff bases based on thiosemicarbazide and evaluation of their inhibitory properties on corrosion of carbon steel in acidic environment 99 124 7457 10.22075/chem.2022.25896.2043 FA Homayoon Eslamizadeh Department of Chemistry, Faculty of Basic Sciences, University of Guilan, Rasht, Iran Asadollah Mohammadi Department of Chemistry, Faculty of Basic Sciences, University of Guilan, Rasht, Iran 0000-0001-6667-2641 Somayeh Mohammadi Department of Chemistry, Faculty of Basic Sciences, University of Guilan, Rasht, Iran Journal Article 2022 01 20 In this work, two Schiff bases named 1-(2-hydroxybenzylidene)-4-phenylthiosemicarbazide (2-HTSC) and 1-(3-hydroxybenzylidene)-4-phenylthiosemicarbazide (3-HTSC) were synthesized and evaluated their inhibitory properties on corrosion of carbon steel in 15% HCl environment. Inhibitory effect of compounds were investigated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), polarization, Scanning electron microscopy (SEM) analysis, X-ray diffraction (EDX) spectroscopy and absorption isotherms. Concentrations of 0.5, 1, 1.5 and 2 mM of the inhibitor were evaluated and the best result was obtained at a concentration of 1.5 mM. The results showed that the 3-HTSC Schiff base has a better inhibitory percentage than the Schiff base 2-HTSC. Adsorption of inhibitors on the steel surface follows all Langmuir adsorption isotherm and the results of thermodynamic parameters indicate physico-chemical adsorption. In the presence of inhibitor, the adsorption rate of chloride ions on the metal substrate decreased by 26% and 74% for inhibitors 2-HTSC and 3-HTSC, respectively, due to the predominance of better interactions of 3-HTSC with the metal substrate in Comparison with 2-HTSC inhibitor. In this work, two Schiff bases named 1-(2-hydroxybenzylidene)-4-phenylthiosemicarbazide (2-HTSC) and 1-(3-hydroxybenzylidene)-4-phenylthiosemicarbazide (3-HTSC) were synthesized and evaluated their inhibitory properties on corrosion of carbon steel in 15% HCl environment. Inhibitory effect of compounds were investigated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), polarization, Scanning electron microscopy (SEM) analysis, X-ray diffraction (EDX) spectroscopy and absorption isotherms. Concentrations of 0.5, 1, 1.5 and 2 mM of the inhibitor were evaluated and the best result was obtained at a concentration of 1.5 mM. The results showed that the 3-HTSC Schiff base has a better inhibitory percentage than the Schiff base 2-HTSC. Adsorption of inhibitors on the steel surface follows all Langmuir adsorption isotherm and the results of thermodynamic parameters indicate physico-chemical adsorption. In the presence of inhibitor, the adsorption rate of chloride ions on the metal substrate decreased by 26% and 74% for inhibitors 2-HTSC and 3-HTSC, respectively, due to the predominance of better interactions of 3-HTSC with the metal substrate in Comparison with 2-HTSC inhibitor. https://chemistry.semnan.ac.ir/article_7457_9f820adf84bf8a1c259f464ba89ea11f.pdf