Abstract
Effective corrosion-protection by plant-extract on metals, in aggressive
service-environment, is dependent on the biochemical constituents of
which the natural plant is made-up. This paper investigates biochemical
characterization of inorganic and organic constituents of Rhizophora
mangle L. leaf for gaining insight on its steel-reinforcement corrosion
mitigating prospect in NaCl-immersed concretes. For the study, atomic
absorption spectroscopy (AAS), Fourier transform infrared spectroscopy
(FT-IR) and phytochemical screening analyses were employed. Totalcorrosion
effect was also studied from steel-reinforced concrete samples,
having different concentrations of the leaf-extract as admixture, and
which were immersed in 3.5% NaCl (simulating saline/marine
environment). Results, by AAS, showed that Rhizophora mangle L. leaf
inorganic constituents were highest in iron, Fe = 10,316.17 μg/g and
lowest in cadmium, Cd = 6.2019 μg/g but has neither lead (Pb) nor
chromium (Cr). Also, organic constituents, by FT-IR, indicated extract from
the leaf constitutes aromatic chained compounds rich in π-electrons as
well as sulphur, nitrogen and oxygen-bearing ligands to which iron (steelrebar)
exhibits coordinate affinity. Phytochemical characterization
showed that the leaf-extract contains alkaloids, tannins, phlobatannins,
saponins, steroids and glycosides. Corrosion-inhibiting prospect testing,
using the leaf-extract, indicated reduced steel-reinforcement totalcorrosion
effects that correlated with the extract admixture
concentrations employed in the 3.5% NaCl-immersed steel-reinforced
concretes.