The quaternary ammonium salts as corrosion inhibitors for X65 carbon steel under sour environment in NACE 1D182 solution: Experimental and computational studies

The effect of quaternary ammonium salts (DDPC and DDQC) with different concentrations on the corrosion inhibition of X65 carbon steel in the sour brine solution at different temperatures were investigated by weight loss, electrochemical measurements, surface analysis (SKP, AFM, SEM, EDS, and ATR-FTIR), and theoretical calculations (DFT, Monte Carlo, and molecular dynamics). It was found that the corrosion rate decreased with increasing inhibitor concentration, and the inhibition efficiency was about 98%. The adsorption of inhibitors on the metal surface followed the Langmuir adsorption isotherm. Furthermore, inhibitors showed good performance at elevated temperatures. The computational studies supported the experimental data well. [Display omitted] •The corrosion inhibition efficiency of DDPC and DDQC is about 98 % in the sour brine solution.•The detailed study on the effect of concentration and temperature using weight loss and electrochemical methods.•Study of surface morphology by SKP, AFM, SEM, EDS, and ATR-FTIR.•The inhibitors adsorb on the iron surface following the Langmuir isotherm.•DFT, Monte Carlo, and molecular dynamics studies substantiate the experimental results.