Browsing by Author "Alisa, C. O."

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    Investigation of Aba river contamination using Eichhornia crassipes as bio-indicator
    (U. P., 2017-06-05) Akagha, C. I.; Ajiwe, V. I. E.; Okoye, P. A. C.; Alisa, C. O.; Nkwoada, A. U.
    The seasonal variation of heavy metal contamination levels in Aba River of Abia State in Nigeria was investigated using Eichhornia crassipies. Routine sampling was performed on bi-monthly bases to cover the Nigerian Rainy season and Harmattan season. Iron (Fe) showed more abundance with maximum concentration (69.5 mg/kg) mainly in Dec/Jan at UST, PZA, ABT and DST sampling points. The lowest concentration of iron was obtained in Apr/May for UST and DST and in Oct/Nov for PZA and ABT. Manganese showed maximum concentration (7 mg/kg) in the dry season at PZA and NBL during Oct/Nov months. The lowest concentration was in Dec/Jan at UST, PZA and ABT which were Harmattan seasons. The varied concentrations of zinc (Zn) demonstrated no pattern or trend except at Oct/Nov of ABT at value of 9.7 mg/kg, while lead (Pb) metal was significantly identified during the months of Feb/March (end of Harmattan) and April/May (beginning of Rains) during the seasonal study. Chromium metal (Cr) was uniformly distributed but significant at NBL during months of Jun/Jul. Nickel (Ni) metal was detected mainly at UST, PZA and NBL at trace levels. Copper was mainly detected during rainy seasons of Apr/May and Jun/July but remained at low concentrations when compared to other metals. Hence, UST and PZA sampling points contained the most active level of heavy metals, while Harmattan season showed the highest phytochemical activity of the heavy metals. Therefore Eichhornia crassipes showed metal removal in the following order Fe > Mn> Cr > Ni > Pb > Zn > Cd.
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    New amine/phenylglycedyl ether adducts for mild steel protection in 1 M HCl: Experimental and computational study
    (Wiley-VCH GmbH, 2020) Akalezi, C. O.; Onwumere, F. C.; Alisa, C. O.; Nnanyereugo, M. N.; Oguzie, E. E.
    The key objective of this study is to ascertain the effect of structure and increased molecular size on the corrosion inhibition potential of two synthesized amines, when compared to their precursor compounds. The product amines were N-(2-hydroxy-3-phenoxy) ethanol amine (NHPE), N,N potentials were assessed using experimental and quantum theoretical modeling and calculations. Some key electronic properties such as highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies, gap energy, dipole moment and sur face area, were calculated and discussed. The various approaches adopted in this study were in reasonable agreement and the following average inhibition efficiency trend was obtained: NNHPE (75.7%)>NHPE (68.3%)> PGE (64.2) >MEA (61.0).
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    Pollution in Nigerian auto-mechanic villages: A review
    (U. P., 2018) Nkwoada, A. U.; Alisa, C. O.; Amakom, C. M.
    The increasing number of malfunctioning automobiles with subsequent increase in emission levels and waste handling is an environmental concern in Nigeria. The spills from lubricants, gasoline, diesel and byproducts of used and spent engine oil constitute the major pollutants in auto mechanic villages in Nigeria. Its environmental pollution has been predominant through soil and groundwater contamination and also poses a major anthropogenic threat. The studied heavy metals on contaminated soil showed that studies had focused on common metals of Cu, Cd, Pb and Zn in the east and west regions, while trace metals were studied in the south and radioactive elements in the north. Statistical evaluation showed high occurrences of Cu, Cd, Pb and Zn in the four geo-political zones of Nigeria. The detrimental effects of auto-mechanic village activities were on humans and also disrupted growth and flowering of arable plants. The remediation application showed that soil type and contaminant characteristics play a major role in determining the type of remediation procedure to be applied. Hence, Nigeria should provide standard repairs and services to automobiles in-line with emerging technology and best environmental practices.
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    Studies on adsorptive behavior of Cd2+ on graphene oxide: Alternative novel approach
    (U. P., 2018-03-03) Nkwoada, A. U.; Alisa, C. O.; Enenebeaku, C. K.; Oguzie, E, E.
    Certain adsorptive mechanisms and interactions often exist within linearized kinetic functions which are largely unreported. A novel inverse saturation modeling was applied to evaluate the adsorptive behavior of super-saturation, saturation, and desorptive processes on linear kinetic function plots using pseudo 1st order, pseudo 2nd order, Elovich and Intra-particle diffusion. Graphene oxide was prepared by room temperature synthesis and used as adsorbent over Cd2+ adsorbate. Batch adsorption process was conducted and four error functions were utilized. The sum of squares of the errors and Sum of absolute errors identified pseudo 2nd order as having the least deviation at 0.113 and 0.337 respectively. The modelled pseudo 1st order reaction had R2 = 0.985 while the inverse saturation model had R2 value of 0.998, both been a better data fit than non-modelled pseudo 1st order R2 at 0.917. The slower reaction kinetics in pseudo 1st order was due to supersaturation during adsorption as shown by inverse saturation point. The correlation coefficient of modeled kinetic plot of pseudo 2nd order, Intra particle diffusion and Elovich had R2 = 1. The Elovich inverse saturation plot showed that the graph was an L-isotherm type indicating progressive saturation. The rate determining step experienced by Intra-particle diffusion was accommodated by wide range of inverse saturation plots showing adsorption, supersaturation and desorption as points of greatest influence. The inverse saturation plot of pseudo 2nd order plot had absolute slope of 2.656 and large intercept of 24.815 driving it's faster reaction kinetics. Hence, the inverse saturation point modelling provided a much better interpretation of adsorptive behavior of graphene oxide adsorbent over Cd2+ adsorbate.