Improved corrosion inhibition of calcium disodium EDTA for mild steel in chloride-contaminated concrete pore solution
Zhicheng Liu, Fengrui Zhang, Xuan Li, Danqian Wang
Abstract
The corrosion inhibition of EDTA-Ca for mild steel in chloride-contaminated concrete pore solution , with EDTA-Na as comparison, was investigated via several electrochemical methods and surface characterizations . Results show that corrosion inhibition efficiency of EDTA-Ca is higher than that of EDTA-Na. Corrosion inhibition efficiency increased with an increase in EDTA-Ca concentration while decreased with the increased EDTA-Na concentration. EDTA-Ca adsorbs physiochemically on surface of mild steel which obeys Langmuir isotherm , while adsorption of EDTA-Na is physical obeying Freundluich isotherm. A much thinner and more compact oxide film with higher Fe 2+ content formed in the presence of EDTA-Ca compared to EDTA-Na. The availability of coordinate bonds for chelation in EDTA-Ca or EDTA-Na plays a critical role in determining the corrosion inhibition efficiency.