Ekemini Ituen

Synthesis, characterization and anticorrosion property of olive leaves extract-titanium nanoparticles composite

Abstract Ethanolic extracts of olive leaves (OLE) in the presence of TiCl4 solution was used to form OLE – Ti nanoparticles composite (OLE-Nano). The particle size of Ti nanoparticles in the composite was determined using particle sizer and the nanoparticles were characterized using UV–vis, FTIR, SEM/EDAX and XRD techniques. Results show that the particles were around 70–74 nm in size and show maximum absorption around 420 nm. Prominent FTIR peaks correspond to C=C, N–H, O–H and C=O functionalities. XRD spectrum shows four distinctive diffraction peaks at 27.42°, 36.07°, 41.23°, and 54.30° corresponding to lattice plane value indexed at (101), (104), (200) and (211) planes of face centered cubic (FCC). The anticorrosion property of the OLE-Nano for mild steel in 1 M HCl at 30–60 °C was assessed using weight loss and electrochemical techniques complemented by surface analysis of the corroded steel specimen in the absence and presence of OLE – Nano with SEM and AFM. Results obtained show that OLE inhibited the acid corrosion of mild steel and the inhibition performance was enhanced in the presence of Ti nanoparticles. The corrosion inhibition effect was found to be concentration and temperature dependent. The inhibition efficiency of the OLE and OLE-Nano were 83.5 and 94.3% respectively at 30 °C but decreased to 51.7 and 85.4% at 60 °C respectively. The OLE-Nano adsorbed on mild steel surface by physical adsorption mechanism as predicted by Langmuir adsorption isotherm model. Potentiodynamic polarization results show that OLE-Nano behaves as mixed type inhibitor.

SOLVENTS EFFECT ON THERMAL STABILITY AND ELECTROCHEMICAL BEHAVIOUR OF GRIFFONIA SIMPLICIFOLIA EXTRACTS AS STEEL CORROSION INHIBITOR IN ACIDIC ENVIRONMENT

Different solvents were used to extract Griffonia simplicifolia and tested corrosion inhibitors for as X80 steel in 1 M HCl solution. The corrosion tests were conducted by thermo-gravimetric analyses (TGA), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) while the surface morphologies were checked by scanning electron microscopy (SEM). The essence was to investigate the effects of the solvents on the yield, phytochemical profile, corrosion inhibition properties and thermal stability of the extracts. The highest yields of 63.24 g kg -1 and 51.63 g kg -1 were obtained with seeds (SEGS) and leaves (LEGS) extracts respectively in ethanol-water (1:1) system. Acetone extract showed presence of all the tested phytochemicals namely alkaloids, tannins, saponins, glycosides, steroids and terpenoids. The highest inhibition efficiencies of 95.86 % (SEGS) and 82.14 % (LEGS) were obtained with acetone extracts. Acetone extract was also most thermally stable being 66.4 % (SEGS) and 50.05 % (LEGS) efficient at 90 °C, followed by ethanol extract while methanol extract was least stable and least efficient. Inhibitors act as mixed type and their addition increased charge transfer resistance and decreased corrosion current density with respect to the free acid solution. Micrographs of the steel surface in some systems show evidence of slight surface protection by the inhibitors. It has been inferred from this study that both acetone and ethanol are better solvents for extraction of Griffonia simplicifolia based corrosion inhibitors.