Synthesis of Some Ethoxylated and Sulfonated Fatty Alcohol Surfactants and Their Inhibition Actions for C-Steel Corrosion in 1 M HCl

Corrosion of metals is an important economic problem globally. The use of corrosion inhibitors, mainly those based on surfactants, is one of the most efficient ways of defending metal surfaces against corrosion. This study aimed to synthesis some novel ethoxylated and sulfonated fatty alcohol surfactants. The symbols B1, B2, and B3 were pointed to R–CH 2 O–(CH 2 CH 2 O) 20 –SO 3 Na, R–CH 2 O–(CH 2 CH 2 O) 20 –H, and R–CH 2 O–(CH 2 CH 2 O) 7 –SO 3 Na, respectively. Spectroscopic methods (FTIR, 1 H NMR) were used to characterize the compounds. Micelle concentration (CMC) for the synthesized surfactants was determined and discussed. The surface tension and thermodynamic properties of these inhibitors were investigated. The ability of the synthesized ethoxylated and sulfonated compounds to inhibit the corrosion of C-steel was investigated. Electrochemical, and surface analysis techniques were used to describe the corrosion behavior in blank and inhibiting solutions. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PP), and electrochemical frequency modulation (EFM) were used as electrochemical techniques at 25 °C. The inhibition efficiency increases with the concentration. A higher inhibition efficiency among the investigated compounds was at the concentration of 300 ppm from compound B1. The investigated surfactants behave as mixed corrosion inhibitors. It was found that the adsorption process obeys Langmuir isotherm. Adsorption parameters were calculated then explained. The adsorption of the investigated compounds is physisorption. The surface morphology of the C-steel and the formed protective film were examined using SEM. The order of inhibition efficiencies was B1 > B2 > B3. The data obtained from various techniques were in good agreement.