Taiwo Felicia Owoeye

Biochemical Characterisation of the Leaf of Morinda Lucida : Prospects for Environmentally-Friendly Steel-Rebar Corrosion-Protection in Aggressive Medium

This paper employs atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR) and phytochemical screening methods for biochemical characterisation of the inorganic and organic constituents of the leaf of Morinda lucida. AAS results showed that this well-known medicinal-plant is high in iron (Fe = 5143.54 µg/g), low in cadmium (Cd = 2.9506 µg/g) and does not contain chromium (Cr). Also, Euclidean hit-list from the FT-IR instrument suggests Morinda lucida leaf-extract contains S-, N-, Br- and O- containing heteroatoms. The phytochemical analyses indicated presence of tannins, phlobatannins, saponins, flavonoids and terpenoids. These results bare prospects on suitability of leaf-extract from Morinda lucida for environmentally-friendly steel-rebar corrosion-protection in aggressive medium. Preliminary tests based on this showed that use of 0.083 wt% cement of Morinda lucida retarded steel-rebar total-corrosion and eventually reduced corrosion rate as admixture in duplicated 3.5% NaCl-immersed concretes, relative to control samples in the same medium.

Effects of Dialium guineense Based Zinc Nanoparticle Material on the Inhibition of Microbes Inducing Microbiologically Influenced Corrosion

This paper investigates the effects of Dialium guineense based zinc nanoparticle material on the inhibition of microbes inducing microbiologically influenced corrosion (MIC) in metals. Extract of leaf from the natural plant were used as precursor for zinc nanoparticle material, which was characterized by scanning electron microscopy and energy dispersive spectroscopy (SEM + EDS) instrument. Sensitivity of the developed zinc bio-nanoparticle material from this on different strains of microbes that are known to induce microbiologically influenced corrosion, in metallic materials, was then studied and compared with that obtained from a commercial antibiotic employed as control. Results showed that the biomaterial capped nanoparticle exhibited inhibited growth of the studied different MIC inducing microbes. Zones of inhibition, the sensitivity measure of the biosynthesized material against the microbial strains either surpassed or compared well with the zones of inhibition from the commercial antibiotic (control). These results engender implication on the prospects of the zinc bio-nanoparticle usages in corrosion inhibition and protection system for metals in microbial corrosion influencing environment.

Investigating Biochemical Constituents of Cymbopogon citratus Leaf: Prospects on Total Corrosion of Concrete Steel-Reinforcement in Acidic-Sulphate Medium

In this paper, the biochemical constituents of Cymbopogon citratus leaf were investigated by atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FT-IR) and phytochemical screening analyses for assessing its steel-rebar corrosion-protection prospects. AAS results showed that the leaf contained Fe = 4,641.025 μg/g, Mn = 849.5069 μg/g, Cu = 171.045 μg/g, Pb = 13.2938 μg/g, Ni = 11.5187 μg/g, Cd = 4.9310 μg/g, but Cr = 0.0 μg/g. FT-IR indicates the leaf-extract contained S-, N-, O-containing heteroatoms and aromatic compounds, which are rich in π-electrons and that are known to inhibit steel-rebar corrosion. Phytochemical screening results showed that Cymbopogon citratus leaf-extract contains tannins, phlobatannins, saponins, glycosides, flavonoids, steroids and terpenoids. Macrocell corrosion tests, as per ASTM G109-99a, showed that the plant reduced total corrosion in 0.5 M H2SO4-immersed steel-reinforced concrete samples. These indicated positive prospects of Cymbopogon citratus as an eco-friendly inhibitor of steel-reinforcement corrosion in concretes designed for acidic sulphate service-environment.

Investigating inhibition of microbes inducing microbiologically-influenced-corrosion by Tectona grandis based Fe-nanoparticle material

In this paper, inhibition of microbes inducing microbiologically-influenced-corrosion (MIC) of metals by Tectona grandis based Fe (iron) Nanoparticle material was investigated. For this, extract was obtained from the leaf of Tectona grandis and this was employed as precursor for synthesizing the Fe-nanoparticle material. From this, the synthesized plant extract based nanoparticle material was characterized using scanning electron microscopy and energy dispersive spectroscopy (SEM+EDS) instrument. The developed Fe bio-nanoparticle material was then employed for sensitivity and/or resistance study application against different strains of microbes that are known to induce microbiologically-influenced-corrosion, in metallic materials, and for this, microbial growth inhibition effect was compared with that from a commercial antibiotic employed as control. Results showed that the Tectona grandis based Fe-nanoparticle exhibited good inhibition effects on the growth of many of the MIC inducing microbes investigated. Sensitivity measures of zone of inhibition against the growth of MIC inducing microbial strains either outperformed or compares well with that obtained from the commercial antibiotic control, in the study. These results indicate positive prospect on the suitability of Fe bio-nanoparticle for corrosion inhibition applications for the protection of metals against microbiological corrosion influencing environment.

Bio-characterisation of Solanum aethiopicum leaf: prospect on steel-rebar total-corrosion in chloride-contaminated-environment

This paper investigates biochemical constituents of Solanum aethiopicum leaf, for its prospect on the total-corrosion reduction of concrete steel-rebar in the chloride-contaminated environment. Atomic absorption spectroscopy (AAS) and Fourier transform infra-red (FTIR) spectroscopy were used for assessment of inorganic and organic constituents of the leaf. Steel-rebar total-corrosion was analysed, as per ASTM G109-99a, from macrocell-current measurements in 3.5% NaCl-immersed steel-reinforced concrete samples that were admixed with different concentrations of the Solanum aethiopicum leaf-extract. By AAS, Solanum aethiopicum leaf was characterised of inorganic constituents Fe = 4645.50 μg/g, Pb = 74.1138 μg/g, Ni = 43.1162 μg/g, Cd = 6.8425 μg/g, Cu = 0.004581 μg/g and Cr = 0.0000 μg/g. By FTIR, the plant was characterised with S-, N-, O- (and a trace of Hg-) containing organic hetero-atoms. Also, the different concentrations of Solanum aethiopicum leaf-extract admixture studied reduced steel-rebar total-corrosion, with physisorption mechanism, in the 3.5% NaCl-immersed steel-reinforced concrete specimens relative to a sample without admixture.