Table 2: Polarization parameters for the corrosion of carbon steel immersed in 0.1 mol L−1 Na2SO4 solution (pH 6.0), in the presence and absence of tannin, for different periods.

𝑗 c o r r (μA cm−2) 𝐸 c o r r (V) 𝑅 𝑝 (Ω cm2)IE (%)

1 day39.66−0.73486.4691.06
1 day with tannin0.883−0.505446.0
3 days20.52−0.73461.3793.03
3 days with tannin1.512−0.726622.2
7 days13.58−0.75481.2175.74
7 days with tannin3.241−0.721984.3