Corrosion Inhibition Behaviour and Adsorption Characteristics of Dapsone Derivatives on Mild Steel in Acid Medium
M. P. Chakravarthy
Department of Studies in Chemistry, University of Mysore, Manasagangothri, Mysore, 570 006, India
K. N. Mohana *
Department of Studies in Chemistry, University of Mysore, Manasagangothri, Mysore, 570 006, India
C. B. Pradeep Kumar
Department of Chemistry, Sarada Vilas College, Mysore-570 005, India
A. M. Badiea
Department of Industrial and Manufacturing System Engineering, Engineering College and IT, Taiz University, Yemen
*Author to whom correspondence should be addressed.
Abstract
Two newly synthesized Dapsone derivatives viz., 3-[(4-{4-[(1H-Indol-3-ylmethylene)-amino]-benzenesulfonyl}-phenylimino)-methyl]-1H-indole (IABPI) and 5-[(4-{4-[(Thiophen-2-ylmethylene)-amino]-benzenesulfonyl}-phenylimino)-methyl]-thiophene (TABPT) were investigated as corrosion inhibitors for mild steel in 0.5 M H2SO4 media by using chemical and electrochemical techniques. Potentiodynamic polarization studies indicated that these two inhibitors behaved as mixed type. These inhibitors were found to obey Langmuir isotherm model. Using this isotherm, thermodynamic adsorption parameters were evaluated. EIS studies showed that the polarization resistance (RP) and double layer capacitance (Cdl) of the inhibitors are concentration dependent. FTIR technique was used to identify the interaction of inhibitor with mild steel surface, whereas persistency of thin protective film of inhibitors on the mild steel surface was carried out by using EDX and SEM.
Keywords: Mild steel, dapsone derivatives, chemical and electrochemical techniques, SEM