Abstract
The adsorption affinity and corrosion protection of two synthesized N-alkylphthalazinone derivatives 2(a-b), namely: 2-(prop-2-yn-1-yl)-4-(p-tolyl)phthalazin-1(2H)-one (a) and 4-(4-chlorophenyl)-2-(prop-2-yn-1-yl) phthalazin-1(2H)-one (b) on carbon steel (CS) in an acidic environment using electrochemical and mass loss methods. The mass loss test at the highest inhibitor concentration produced a maximum corrosion efficiency of 93.4% for inhibitor (a). Thermodynamic parameters were determined while the inhibitors' adsorption process was investigated. The inhibitory molecules adsorption on the CS substrate accompanied the Langmuir isotherm. As a function of inhibitor concentration, the thermodynamic activation functions of the dissolution process were calculated. Surface examination such as scanning electron microscopy (SEM), fourier transfer infrared spec-troscopy (FTIR), and atomic force microscopy (AFM) techniques were used to confirm the adsorption phe-nomenon. Also investigated were quantum chemical parameters to approve the donor-acceptor system of the synthesized N-alkylphthalazinone derivatives. The theoretical values are in good correlation with the experi-mental values.