Enhancing the inhibition action of cationic surfactant with sodium halides for mild steel in 0.5 M H2SO4

• N-hexadecylpyridinium bromide (PyC16Br) significantly inhibits the corrosion of mild steel in H2SO4 solution.
• PyC16Br act as a mixed-type inhibitor in 0.5 M H2SO4 solutions.
• Halides markedly enhances the inhibition action when added to PyC16Br.
• Both PyC16Br and PyC16Br/halide systems the adsorption obeys Temkin adsorption isotherm.

The synergistic effect of N-hexadecylpyridinium bromide (PyC16Br) and different sodium halides on the corrosion of mild steel in 0.5 M H2SO4 solution has been investigated using electrochemical methods, X-ray diffraction (XRD) and scanning electron microscope (SEM). Experimental results showed that the protection efficiency (Picor) of PyC16Br improved at either considerable high concentration near its critical micelle concentration (CMC) or in the presence of the different halides with different extents. The synergism parameter (Sθ) is found to be greater than unity indicating high Picor. Corrosion products phases and surface morphology were studied using XRD and SEM, respectively.