Electrochemical investigations of the systematic effects of thiourea and its derivatives on the corrosion of mild steel in acidic media

ABSTRACT PhD THESIS ELECTROCHEMICAL INVESTIGATIONS OF THE SYSTEMATIC EFFECTS OF THIOUREA AND ITS DERIVATIVES ON THE CORROSION OF MILD STEEL IN ACIDIC MEDIA Muzaffer OZCAN DEPARTMENT OF CHEMISTRY INSTITUTE OF NATURAL AND APPLIED SCIENCES UNIVERSITY OF ÇUKUROVA Supervisor: Assosc. Prof. Dr. İlyas DEHRİ Year: 2005, Pages: 132 Jury: Assosc.Prof.Dr. İlyas DEHRİ Prof. Dr. Birgül YAZICI Assist. Prof.Dr. A.Murat GİZÎR Prof. Dr. Mehmet ERBİL Prof. Dr. Melih BAYRAMO?LU The effects of thiourea(TU), methylthiourea(MTU), phenylthiourea(PTU), thioacedamide(TacA) and thiobenzamide(TBA) on the corrosion behavior of mild steel in 0.1 M solution of H2SO4 have been investigated in relation to the concentration of fhioamides and temperatures. AC impedance, polarization resistance measurement and polarization curves measurement techniques have been used to obtain experimental data. The percent inhibition efficiency(IE %), free energy of adsorption(AGads) and activation energy(Ea) have been determined in the presence of these compounds. The results showed that these compounds revaled a good corrosion inhibition. The effect of molecular structure on the inhibition efficiency on corrosion has been investigated by ab initio quantum chemical calculations. The electronic properties such as Ehomo, Elumo, LUMO-HOMO energy gap and molecular orbital densities were calculated.The relations between the percent inhibition efficiency(IE%) and some quantum chemical parameters have been discussed and obvious correlations were found. Key Words: Corrosion inhibition; Thiourea and its derivatives; EIS; Quantum chemical calculations. II