Recent developments in sustainable corrosion inhibition using ionic liquids: a review

Mechanism of corrosion inhibition using ionic liquids

Similar to traditional organic inhibitors, ionic liquids become effec- tive by blocking the anodic and cathodic sites of the metal surface. In other words, ionic liquids retard or slow down the rate of anodic oxida- tion and cathodic reduction reactions. Likhanova et al. [68] postulated that anodic and cathodic reactions of a divalent metal with and without ionic liquids in H₂SO₄ (sulphate ion) and HCl (chloride ion) can be writ- ten as follows:

1. 
   Anodic reactions without ionic liquids (ILs)
   

M þ nH₂O↔MðH₂OÞ_nðadsÞ ð1Þ
back to the anti-bonding molecular orbitals of the inhibitors through a phenomenon called as retro-donation. Donation and retro-donation (back-donation) toughen each other through synergism [70]. A pictorial
presentation of a choline based ionic liquid on iron surface in acidic me-

nðadsÞ

4

n

4

ads
MðH₂OÞ þ SO²⁻=2Cl⁻↔MhðH₂OÞ SO²⁻=2Cl⁻i
ð2Þ
dium of HCl is shown in Fig. 3 [69].

−
MhðH OÞ SO²⁻=2Cl⁻i
↔M ðH OÞ SO =2Cl



−
þ 2e ð3Þ

2.