Available online www.jocpr.com Journal of Chemical and Pharmaceutical Research, 2015, 7(10S):120-126 Research Article ISSN : 0975-7384 CODEN(USA) : JCPRC5 120 Sodium nitrite as corrosion inhibitor for mild steel in simulated concrete pore solution M. Pandiarajan 1* S. Rajendran 1,2 J. Sathiya Bama 1 and R. Joseph Rathish 3 1 Corrosion Research Centre, PG and Research, Department of Chemistry, GTN Arts College, Dindigul, Tamil Nadu, India 2 Corrosion Research Centre, Department of Chemistry, RVS School of Engineering and Technology, Dindigul, Tamil Nadu, India 3 PSNA College of Engineering and Technology, Dindigul, India _____________________________________________________________________________________________ ABSTRACT The corrosion inhibition effect of mild steel in simulated concrete pore solution (SCPS) by Sodium Nitrite and Zn 2+ has been investigated using weight loss method and cyclic voltammetry. The results show that 93% of inhibition efficiency is achieved with binary system consisting of 100 ppm of sodium nitrite – 50 ppm of Zn 2+ . Surface evaluation technique like FTIR is used to determine the nature of the protective film formed on the metal surface. The protective film consists of Fe 2+ - SN complex, Zn 2+ - SN complex and Zn(OH) 2 . Cyclic voltammetry study reveals that the protective film is more compact and stable even in 3.5% NaCl environment. Key words: Concrete Corrosion, Simulated Concrete Pore Solution, Mild Steel, Sodium nitrite, Well water. _____________________________________________________________________________________________ INTRODUCTION Effect of organic inhibitors on chloride corrosion of steel rebars in alkaline pore solution has been investigated by Marina Cabrini et al., The inhibition properties of aspartic and lactic acid salts are compared with nitrite ions with regard to their effect on critical chloride concentration. The tests were carried out on carbon steel specimens in simulated pore solutions with initial pH in the range of 12.6 to 13.8. The results confirm that 0.1 M aspartate exhibits an inhibiting effect comparable with nitrite ions of the same concentration[1].The inhibition of corrosion of reinforcing steel in simulated concrete pore solution (SCPS) has been studied using mass loss, gasometric measurements, potentiodynamic polarization and impedance studies using Mezlocillin (MZN) as a green inhibitor. The studies clearly revealed that MZN acted as cathodic inhibitor. Diffused reflectance spectra confirmed the formation of adsorbed film of inhibitor on reinforcing steel in SCPS[2].The corrosion inhibition effect and mechanism of D-sodium gluconate for reinforcing steel in the simulated concrete pore solution containing Cl - were studied by electrochemical techniques, including corrosion potential, potentiodynamic polarization, and electrochemical impedance spectroscopy measurements. The results indicate that 0.01 M D-sodium gluconate showed a good corrosion inhibition effect on reinforcing steel in the simulated concrete pore solution containing 0.1 M NaCl because it strongly hindered the anodic reactions, by forming a compact adsorptive film by strong chelation and effectively inhibit the initiation of reinforcing steel corrosion[3].The Effect of NO 2 - on the early stages of pitting corrosion of Q235 carbon steel in a simulated concretepore solution (pH=11) was studied by means of polarization curves, Mott-Schottky curves and XPS methods. It was found that, NO 2 - inhibits both the stable pitting corrosion and the meta stable pitting corrosion [4]. The newly synthesized polymer, azo methine-based polyester, has been employed as inhibitor against the corrosion of rebar in artificially simulated concrete pore solution with chloride contamination (blank) by means of Tafel polarization and electrochemical impedance measurements. Polarization studies exhibited the maximum inhibition efficiency of 98% at 1000 ppm concentration. Electrochemical studies revealed the mixed-type nature of the inhibitors [5].