The effect of iodide ions on the corrosion inhibition of aluminium in 2M HCl in the presence of
polyvinylpyrollidone (PVP) was studied using gasometric (hydrogen evolution) technique at 30-60°C. Results obtained
showed that PVP effectively reduces the corrosion rates of aluminium in the acid medium. Inhibition efficiency (%I)
increases with increase in concentration of PVP. Increase in temperature increases corrosion rate but decreases
inhibition efficiency. The addition of iodide ions enhanced the inhibition efficiency of PVP considerably.
Adsorption of PVP and PVP + KI followed Temkin adsorption isotherm. Phenomenon of physical adsorption is proposed
from the obtained Eα and ∆G°ads values. The synergistic parameter (S1) obtained was found to be greater than unity,
which indicates that the enhanced inhibition efficiency caused by the addition of iodide is only due to synergistic