Synthesis, spectroscopic analysis and electrochemical studies of novel organic compound based on N-alkylphthalazinone chemistry as corrosion inhibitor for carbon steel in 1M HCl

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 spectroscopy (FTIR), and atomic force microscopy (AFM) techniques were used to confirm the adsorption phenomenon. 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 experimental values.