Synergistic effect between non-ionic surfactant and halide ions in the forms of inorganic or organic salts for the corrosion inhibition of stainless-steel X4Cr13 in sulphuric acid

The inhibition behaviour of the TRITON-X-405 mixed with KBr or C4H12NI in 2.0 M H2SO4 on the ferritic SS was studied using potentiodynamic and EIS measurements. The electrochemical data showed that mixtures used in this study adsorbed on the SS’s surface, in agreement with the Flory–Huggins adsorption isotherm. Polarization and EIS measurements indicated that KBr or C4H12NI had a significant synergistic effect with TRITON-X-405 in 2.0 M H2SO4. This effect was more pronounced when adding C4H12NI, and at concentrations above the CMC of the used mixtures, which had been determined via corrosion-kinetic parameters. The inhibitive mechanism is proposed.

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► Synergistic effect between TRITON-X-405 and KBr or C4H12N I was studied.
► The CMC of the used mixtures had been determined via corrosion-kinetic parameters.
► At c < CMC co-adsorption effect of I− ions, mixed micelles could be formed at a c > CMC.
► Chemisorption is suggested.
► Adsorption of chosen mixtures, obeys the Flory–Huggins isotherm.