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Synergistic Effect of Isopropylamine with Cl- and SO42-
on Inhibition of Mild Steel Corrosion in Phosphoric Acid
V.
Chandrasekaran1, K. Kannan 1*and M. Natesan2
1Department
of Chemistry, Government College of Engineering, Salem-636 011, T.N.
India., E-mail:
chandru_v20042000@yahoo.co.in and
kannan_k2002@yahoo.co.in
2Central Electrochemical Research
Institute, Karaikudi – 630 006, T.N. India,
E-mail:
mnatesan@rediffmail.co.in,
Fax:91-04565-227779, 227713,227205,227206
Abstract:Synergistic
effect of Isopropylamine with Cl- and SO42-
on the inhibition of corrosion of mild steel in phosphoric acid medium
has been investigated by using mass loss, potentiostatic polarization
and A.C. impedance techniques at 302K. The addition of chloride and
sulphate ions inhibits the mild steel corrosion in phosphoric acid.
Isopropylamine showed very good inhibition efficiency. It has been
found that the inhibition efficiency of the inhibitor increased with
increase in inhibitor concentration and decreases with increase in
acid concentrations. The maximum inhibition efficiency of
Isopropylamine in 1N and 5N H3PO4 at 2.5% of
Isopropylamine were found to be 96.92% and 90.39% respectively. Under
the Synergistic effect, in the presence of 500 ppm of chloride with
Isopropylamine inhibition efficiency was 98.24% in 1N and 92.03% in 5N
phosphoric acid and in the presence of 500ppm of sulphate with
Isopropylamine inhibition efficiency was 97.50% in 1N and 91.42% in 5N
phosphoric acid. The adsorption of this compound on the mild steel
surface has been found to obey Temkin’s adsorption isotherm.
Keywords:
Mild steel, phosphoric acid, corrosion, inhibition, potentiostatic
polarization.
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