Investigation on the synergy mechanism of mixed inhibitors – Mannich base and Na₂WO₄ on Fe surface by molecules dynamic simulation

ABSTRACT

Previous experimental results shows mixed Mannich base (C₁₅H₁₅NO) and Na₂WO₄ have demonstrated excellent corrosion prevention, and the best corrosion inhibition efficiency is 96.19% when the mixing ratio of the two components is 1:1. In order to clearly understand to inhibition mechanism, molecular dynamics were used to model the inhibition effects of C₁₅H₁₅NO or Na₂WO₄ molecule on the iron surface. The simulation results indicate there are synergistic effect between C₁₅H₁₅NO and Na₂WO₄. the synergistic effect has three main factors: for one, the synergistic effect is due to the ${\mathrm{W}\mathrm{O}}_4^{2-}$ (small) can fill in the voids of the C₁₅H₁₅NO (big), the mixed inhibitor film is denser than single inhibitor film; moreover, the ${\mathrm{W}\mathrm{O}}_4^{2-}$ forms H-bond group with H₃O⁺, which makes corrosive particles harder to pass through adsorption film, simultaneously; In addition, the mixed inhibitor significantly reduces the free charges and ions on Fe surface, which makes metal structure is more stable.

KEYWORDS:

• Corrosion inhibition
• molecular dynamics simulation
• iron surface
• adsorption energy

Acknowledgements

Jun Hu and Neng Li conceived and designed the experiments; Zhen Wang and Tiantian Wang performed the simulations; Zhen Wang and Peiyin Xu analysed the data; Jun Hu and Neng Li revised the paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Jun Hu http://orcid.org/0000-0002-3075-9291

Additional information

Funding

Financial support from the National Natural Science Foundation of China [grant number 21676216]; China Postdoctoral Science Foundation [grant numbers 2014M550507; 2015T81046] are greatly acknowledged.