RHIZOPHORA MANGLE L. LEAF BIOCHEMICAL CHARACTERIZATION: NATURAL-GREEN TOTAL-CORROSION INHIBITION PROSPECT ON CONCRETE STEEL-REINFORCEMENT IN 3.5% NaCl

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. Total-corrosion 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 (steel-rebar) 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 total-corrosion effects that correlated with the extract admixture concentrations employed in the 3.5% NaCl-immersed steel-reinforced concretes.

C6h18n4 Behaviour on Reinforcing-Steel Corrosion in Concrete Immersed in 0.5 M H2so4

“…ts from the Kolmogorov-Smirnov goodness-of-fit test-applications for the fittings of the corrosion datasets to the Normal and the Weibull probability distribution functions. Also (2) ), and variations from such Normal and Weibull , the reliability of the obtained expected values followed from their respective (3) (4) ,of corrosion tests, like the Smirnov goodness-of-fit (5) concentrations was assessed of better-fit of the scatter (%), according to: [48][49][50][51][52][53][54] (6) electrochemical measurements of corrosion rate using the Normal the plots of Normal ), of obtaining each mean…”

“…-2, that increase in the C 6 H 18 N 4 admixture concentration in the steel-reinforced concrete samples for the H 2 SO 4 medium leads to increase in the corrosion-inhibition efficiency. [55][56][57] Further analyses of this performance model by the C 6 H 18 N 4 admixture, via probing of mathematical correlation modeling, 35,46,49,58 as per ASTM G16-13(2019), 36 indicated that the inhibition efficiency, η (%), exhibited a relationship with the C 6 H 18 N 4 concentration, ρ (M), which could be represented as:…”

Study on the effects of green-based plant extracts and water-proofers as anti-corrosion agents for steel-reinforced concrete slabs

“…As a further matter, there is a growing appeal for developing different green-based corrosion inhibitors acquired from plant extracts in combating the corrosion of reinforced steel in concrete structures because of the less toxic and biodegradable nature of the extracts [11,[16][17][18][19][20]. Studies reported that the suitability of the N-, S-, and O-containing and π electron-rich leaves extracts of Phyllanthus muellerianus [18], Chamaerops humilis L. [20], and Olea europaea [21] acted as an effective anticorrosion agent for reinforcing steel in concrete.…”

Anticorrosion Behaviour ofRhizophora mangleL. Bark-Extract on Concrete Steel-Rebar in Saline/Marine Simulating-Environment

“…Studies indicated that R. mangle L. bark-extract is rich in tannins [47, 48, 51], from which it could be noted that tannins from Rhizophora apiculata ( R. apiculata ), a plant sharing same Rhizophoraceae taxonomical family, have been reported as effective inhibitor of steel corrosion [52–54]. Also, recent scientific journals [55, 56] via collaborative work by authors of this study with other researchers, have detailed that R. mangle L. leaf-extract and R. mangle L. bark-extract are constituted of lone-pairs/ π -electron rich, organic, biochemical compounds [45]. The constitution of the biochemical compounds detailed in [55, 56] in the leaf and bark of R. mangle L. portend corroborations for the positive performances exhibited by the extracts on the inhibition of reinforcing-steel corrosion in sulphuric acid-immersed concrete [57–61].…”

“…Also, recent scientific journals [55, 56] via collaborative work by authors of this study with other researchers, have detailed that R. mangle L. leaf-extract and R. mangle L. bark-extract are constituted of lone-pairs/ π -electron rich, organic, biochemical compounds [45]. The constitution of the biochemical compounds detailed in [55, 56] in the leaf and bark of R. mangle L. portend corroborations for the positive performances exhibited by the extracts on the inhibition of reinforcing-steel corrosion in sulphuric acid-immersed concrete [57–61]. However, while R. mangle L. leaf-extract has also been applied for effectively inhibiting reinforcing-steel corrosion in NaCl-immersed concrete [62, 63], no study have used R. mangle L. bark-extract for corrosion-inhibition of steel-rebar in this medium.…”