Electrode Potential Evaluation of Effect of Inhibitors on the Electrochemical Corrosion Behaviour of Mild Steel Reinforcement in Concrete in H2SO4
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The electrochemical corrosion behaviour of mild steel embedded in concrete, and partially immersed in 0.2M
H2SO4, was studied in this investigation at ambient temperature by potential monitoring technique. The
experimental work was performed with a digital multimeter and a Cu/CuSO4 electrode (CSE) as the reference
electrode. Extracts of carica papaya leaves and sodium nitrite (NaNO2) in different concentrations were
separately and in combination, used as inhibitors. This paper reports the observed electrochemical response
from the electrode potential monitoring of the embedded steel rebar during the experiments. The results
obtained, showed a reduction in the active corrosion reactions behaviour of the embedded mild steel in
concrete with added different concentrations of sodium nitrite and the pawpaw leaves extracts in the acidic
test environment. This reduced active corrosion reaction was an indication of corrosion inhibition / protection
characteristic. The observed inhibition was associated with the protective film provided on the embedded
steel’s surface in the concrete by the complex chemical compounds of the plant leaves’ extracts and of the
sodium nitrite with the alkaline composition/environment of the concrete constituents. The protective film
prevented and/or reduced the chloride ions penetration to the steel surface. The combination of c. papaya
extracts and the NaNO2 solution also provided effective corrosion inhibition of the embedded steel by
synergism. The 100% concentration of each of the inhibitors and when in combinations, exhibited the most
effective corrosion inhibition performance in the sulphuric acid test environment.
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TP Chemical technology