The effect of oxide primidine derivatives on the corrosion of soft steel in 1 M hydrochlori̇c aci̇d experimental and theoretical study

In this thesis, compounds namely,1-Amino-5-(4-methyl benzyl)-4-(4-methyl phenyl) pyrimidin-2(1H)-thione(AMMP), 1-(5-(4-Methoxybenzoyl)-4-(4 methoxyphenyl)-2- oxopyrimidin-1(2H)-yl)-3-phenylthiourea(MMOPH),1-(5-(4-Methoxybenzoyl)-4-(4-methoxyphenyl)-2-oxopyrimidin-1(2H)-yl)-3-(4-chlorophenyl)urea(MMOP),1-(5-(4-Methoxybenzoyl)-4-(4-methoxyphenyl)-2-oxopyrimidin-1(2H)-yl)-3-(4 oxopyrimid methoxyphenyl) urea (MMOM), 1-(5-(4-Methoxybenzoyl)-4-(4-methoxyphenyl)-2-oxopyrimidin-1 (2H)-yl)-3-(4-methyl phenyl) thiourea] (MMOPM) has been investigated as a corrosion inhibitor for mild steel in a 1 M HCl solution. SEM, EDX, and AFM were conducted to identify the surface morphology of the MS system in the presence and existence of corrosion inhibitors. The electrochemical results showed that compounds act as mixed-type inhibitors. The resistance polarization for inhibitors was found to obey an order in the MS system However, AMMP was found to be better than MMOM, MMOP, MMOPM, and MMOPH in mild steel systems (IE = 94,04%in comparison with 92.06%, 82.47%,62.02%, and 56.52%at an immersion time of 168 h, respectively), The Langmuir isotherm system revealed the best match, and the type of adsorption was physisorption and chemisorption in the system. The free energy of AMMP, MMOM, MMOP, MMOPM, and MMOPH compounds are otained as 41.1,-35.6, -38.7, -43 and - 44.7 kj.mol-1. Quantum chemical results showed that the adsorption molecules of inhibitors take place predominantly through protonated structures, and agreed with experimental results. The adsorption of inhibitors molecules on Fe surfaces was further verified by molecular dynamic simulations, The results showed that compounds can be used as new corrosion inhibitors for mild steel in aggressive environments. KEYWORDS: Mild steel, Oxo-pyrimidine, Environment, Corrosion resistance, EIS theroetical studies July 2023, 166 Page