F. E. Okieimen

University of Benin, Benim, Edo, Nigeria

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Publications (101)132.43 Total impact

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    Raymond A Wuana · Felix E Okieimen · Rebecca N Vesuwe
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    ABSTRACT: Majority of contaminated sites in the world contain complex mixtures of heavy metals and organic contaminants from diverse natural processes and anthropogenic activities. Mixed interactions of heavy metals and organic contaminants may affect their bioavailability and accumulation in soil and biota through synergistic or antagonistic processes. Evaluation of contaminant bioavailability is a necessary component of the overall site assessment process for establishing either bioavailability-based or risk-based, site-specific remedial options. However, contemporary approaches aimed at the effective characterisation of contaminated soils for risk assessment, remedial and regulatory purposes are frequently challenged by knowledge gaps in contaminant bioavailability, mixed contaminant effects and emerging contaminants. Understanding mixed contaminant interactions at the elemental and molecular levels is, therefore, imperative not only to explain the underlying mechanisms controlling the fate and transport of these contaminants in soils, but also predict their bioavailability, ecotoxicological effects on natural communities under realistic exposure conditions and remediation endpoints. In this paper, scattered literature is harnessed to review specific soil-contaminant interactions, inter-contaminant (metal-metal, organic-organic, metal-organic) interactions and their implications for bioavailability, risk assessment and soil remediation.
  • L. O. Ekebafe · D. E. Ogbeifun · F. E. Okieimen
    12/2012; 1(1):6-11. DOI:10.5923/j.ajps.20110101.02
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    Raymond A. Wuana · Felix E. Okieimen · Blessing Ogoh
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    ABSTRACT: Chemical fractionation patterns and plant tissue concentrations were used to assess nickel, copper, zinc, cadmium, and lead phytoavailability to maize in a soil amended with metal salts or poultry manure. A sandy loam was treated with 80–400 mg kg−1 doses of a quinternary mixture of the metal nitrates either directly or as spiked poultry manure. The European Communities Bureau of Reference sequential extraction procedure partitioned the metals among three operationally defined pools in the soil. Metal mobilities were lower in the poultry manure–amended than the metal salt–treated soil, indicating the manure's ability to fix the metals in soil. Pot experiments revealed high metal transferabilities with no apparent phytotoxic symptoms in maize at the doses applied, suggesting some degree of tolerance to the metals. Heavy-metal concentrations in maize increased linearly with metal doses in metal salt–treated soil, but were less phytoavailable in soil amended with poultry manure. Heavy-metal concentrations in maize were reasonably predicted from soil parameters using stepwise multivariate regression models. The findings are useful in the assessment and remediation of heavy metal–contaminated soils.
    Communications in Soil Science and Plant Analysis 11/2012; 43(20). DOI:10.1080/00103624.2012.716124 · 0.42 Impact Factor
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    L.O. Ekebafe · J.E. Imanah · F.E. Okieimen
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    ABSTRACT: The effect of carbonization on the processing characteristics of rubber seed shell powder was studied. Rubber seed shells were carbonized at different temperatures and then ground into fine powder. The various powders obtained were then characterized by pH, bulk density, moisture content, iodine adsorption value, yield%, conductivity and loss on ignition. The results show that there was a significant change in the pH as the heating temperature increases. The bulk density and moisture content decrease with increasing heating temperature while the iodine adsorption number and the loss on ignition increase with increasing heating temperature thus showing that carbonization has a significant influence on the processing characteristics of rubber seed shell.
    Arabian Journal of Chemistry 08/2012; 75. DOI:10.1016/j.arabjc.2012.07.018 · 2.68 Impact Factor
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    Raymond A. Wuana · Felix E. Okieimen
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    ABSTRACT: Scattered literature is harnessed to critically review the possible sources, chemistry, potential biohazards and best available remedial strategies for a number of heavy metals (lead, chromium, arsenic, zinc, cadmium, copper, mercury and nickel) commonly found in contaminated soils. The principles, advantages and disadvantages of immobilization, soil washing and phytoremediation techniques which are frequently listed among the best demonstrated available technologies for cleaning up heavy metal contaminated sites are presented. Remediation of heavy metal contaminated soils is necessary to reduce the associated risks, make the land resource available for agricultural production, enhance food security and scale down land tenure problems arising from changes in the land use pattern.
    10/2011; 2011(2090-4614). DOI:10.5402/2011/402647
  • A. K. Akinlabi · F. E. Okieimen
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    ABSTRACT: Studies into how heat, oxygen, ozone, water, and some organic solvents affect the physico-mechanical properties of vulcanizates prepared from blends of natural rubber (NR) and low molecular weight natural rubber (LMWNR) were investigated. Various ratios of NR and LMWNR (100:0, 95:5, 90:10, 80:20, 50:50, 25:75 10:90, 5:95, and 0:100 w/w) were mixed and labeled as mixes A to I. The physico-mechanical properties of all the vulcanizates before and after ageing in oven, oxygen, ozone, and water were measured and compared while the resistance of the vulcanizate in toluene, carbon tetrachloride, acetone, ethanol, cyclohexane, mineral oil, and brake fluid were determined in terms of swelling and solubility measurements. From the unaged results, mix A with 100% NR has the best physico-mechanical properties. After degradation, mix C with 10% LMWNR showed the best ageing resistant. Similarly, mix D with 20% LMWNR showed more resistance in most of the solvents used, and this was closely followed by mix C. The results generally have proven that LMWNR is capable of improving the ageing properties and solvent resistance of NR. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
    Journal of Applied Polymer Science 07/2011; 121(1):78-85. DOI:10.1002/app.33286 · 1.64 Impact Factor
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    ABSTRACT: The impact of storm water run-off from a location of intensive application of CCA in wood treatment on the quality of sediment of the receiving water body was examined. Sediment samples were collected along Ogba River. Physico-chemical characteristics as well as total levels of As, Cr and Cu in sediment samples were determined. Physico-chemical analysis of composite sediment samples upstream and downstream showed pH of sediments to be neutral (6.95 upstream and 6.90 downstream). The sand content for downstream sediment was 90.52 and 87.52% for upstream sediment sample. Total levels of 3.3-14.9 mg kg-1 As, 3.1-116.6 mg kg-1 Cr, and 13.7-16.4 mg kg-1 Cu were obtained for downstream sediment samples and 2.2-2.3 mg kg-1 As, 8.1-13.1 mg kg-1 Cr, and 6.0-7.4 mg kg-1 Cu were obtained for upstream samples. Sequential extraction procedure involving six steps was used to evaluate the partitioning of As, Cr and Cu in the sediments. The results showed that the bioavailable fraction of sediment 20 m downstream was 10%, 100% and 20% of the total levels of As, Cr and Cu respectively in the sediment.
    Chemical Speciation and Bioavailability 04/2011; 23(2):118-124. DOI:10.3184/095422911X13032334445780 · 0.38 Impact Factor
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    ABSTRACT: The lethal effects resulting from incessant release of toxic surfactant-containing industrial chemicals into the Niger Delta Ecological Zone of Nigeria was studied using a laboratory toxicity test. The study employed the Organisation for Economic Development and Cooperation (OECD) 203 protocol. The test organism (Tilapia guineensis [fish]) was obtained from a brackish water environment and exposed to Neatex (industrial detergent) and Norust CR 486 (corrosion inhibitor) at concentrations of 6.25, 12.5, 25, 50, and 100 mg/L for 96 h. The ecological endpoint considered was mortality at 96 h, and the results obtained indicate that concentration and duration of exposure influenced the effects of the test chemicals. The 96-h lethal concentration (LC(50)) values for the industrial detergent and corrosion inhibitor were 46.52 +/- 2.16 and 13.95 +/- 0.80 mg/L, respectively. Differential toxicity was observed between the industrial detergent and corrosion inhibitor at the level of F (1,28) = 8.22, P < 0.05, with the corrosion inhibitor exhibiting a higher toxicity level. The brackish water fish were more sensitive to Norust CR 486 than to the industrial detergent. The mean mortality rate in response to the test chemicals was significantly higher than that to the control treatment at F (2,42) = 42.07, P < 0.05. The observed concentrations are indicative of early warning signs of water quality deterioration, as well as ecological effects on aquatic organisms.
    Turkish Journal of Biology 01/2011; 35(2). DOI:10.3906/biy-0904-13 · 1.34 Impact Factor
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    S O P Urunmatsoma · E U Ikhuoria · F E Okieimen
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    ABSTRACT: Cow dung used as soil amendments and a sequential chemical speciation (six steps) procedure were used to predict the uptake of Cr, Cu and As by maize (Zea mays) plant in chromated copper arsenate (CCA) contaminated soil. A pot experiment containing the contaminated soil samples with different percentage levels of amendments and control (no amendment) was set up. The relative concentrations of the metals in the CCA contaminated soil were established as Cr 265.84 mg/kg, Cu 155.82 mg/kg and As 33.09 mg/kg. However, with the use of speciation and calculations based on mobility factor (M f), the relative toxicity of the metals in the soil was established as As (60%) > Cr (19%) > Cu (8%). The amendment, rich in organic matter raised the pH level of the soil, demobilized the metals rendering them unavailable through bounding resulting into relatively lower uptake by plants in soils with amendment when compared with plants in the control pots.
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    ABSTRACT: The development of high-performance composite materials from locally sourced and renewable materials was investigated. Rubber seed oil polyurethane resin synthesized using rubber seed monoglyceride derived from glycerolysis of the oil was used as matrix in the composite samples. Rubber seed oil-based polyurethane composite reinforced with unidirectional sisal fibers were prepared and characterized. Results showed that the properties of unidirectional fiber-reinforced rubber seed oil-based polyurethane composites gave good thermal and mechanical properties. Also, the values of tensile strengths and flexural moduli of the polyurethane composites were more than tenfold and about twofold higher than un-reinforced rubber seed oil-based polyurethane. The improved thermal stability and the scanning electron micrographs of the fracture surface of the composites were attributed to good fiber–matrix interaction. These results indicate that high-performance “all natural products” composite materials can be developed from resources that are readily available locally.
    Materials and Design 10/2010; 31(9-31):4274-4280. DOI:10.1016/j.matdes.2010.04.013 · 3.50 Impact Factor
  • D. Balköse · T. O. Egbuchunam · F. E. Okieimen
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    ABSTRACT: Soaps are a class of surface active compounds derived from natural oils and fats. Double decomposition reactions permit the synthesis of metallic soaps, which are long-chain carboxylates of metal ions, from alkaline ones such as sodium, potassium or ammonium soaps. Metallic soaps are commercially important as they find use in diverse applications such as driers in paints or inks, components of lubricating greases, heat stabilizers for plastics (especially PVC), catalysts and water proofing agents, fuel additives and cosmetic products amongst others. Many of these applications are related to the thermal properties of these compounds and the thermal behaviour of metal soaps in terms of decomposition processes is of great importance. Rubber seed oil (RSO) which is an unsaturated triglyceride abundantly available in Nigeria, India and Australia is an excellent starting material for metal soaps. In this study rubber seed oil having 2.2% myristic acid, 7.6% palmitic acid, 10.7% stearic acid, 20.61% oleic acid, 36.62% linoleic acid, 22.5% linolenic acid was used in making barium, calcium, cadmium and zinc soaps. The thermal behaviour of soaps (Ba, Ca, Cd and Zn) of rubber seed oil for use as additives in the processing of poly(vinyl chloride) (PVC) was investigated by thermal gravimetry and differential scanning calorimetry. The stability of the soaps was examined by thermogravimetry up to 873 K at a constant heating rate of 10 °C min−1. The soaps were found to be thermally stable up to 473 K as they recorded less than 5% mass loss at this temperature with values of apparent activation energy for decomposition varying from 52 to 96 kJ mol−1. Differential scanning calorimetric studies of the soaps revealed melting and decomposition behaviour of metal soaps.
    Journal of Thermal Analysis and Calorimetry 08/2010; 101(2):795-799. DOI:10.1007/s10973-010-0940-4 · 2.21 Impact Factor
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    R. A. Wuana · F. E. Okieimen · J. A. Imborvungu
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    ABSTRACT: Changes in heavy metal speciation and uptake by maize in a soil before and after washing with chelating organic acids, citric acid, tartaric acid and ethylenediaminetetraacetic acid were assessed. A sandy loam was collected from the vicinity of the Benue industrial layout, Makurdi, Nigeria and spiked with a quinternary mixture of nickel, copper, zinc, cadmium and lead nitrates to achieve higher levels of contamination. Batch soil washing experiments performed on 1.0 g portions of the spiked soil using 0.05 M chelating agents at a solid:liquid ratio of 1:25 showed that washing efficiencies varied in the order: ethylenediaminetetraacetic acid> citric acid> tartaric acid with metal extraction yields typically following the sequence, copper> nickel> zinc> cadmium> lead. Sequential extractions proposed by the European Communities Bureau of Reference method used to assess the redistribution of heavy metal forms in the soil showed that apparent metal mobilities were reduced upon soil washing. Citric acid removed most of the metals hitherto associated with the exchangeable and reducible fractions; tartaric acid, the exchangeable metal pools; and ethylenediaminetetraacetic acid, the non-residual metal pools. Heavy metal assay of harvested biomass of maize grown on unwashed and washed soil samples indicated that metal transfer coefficients, decreased in the order of treatment: ethylenediaminetetraacetic acid <citric acid <tartaric acid <unwashed soil. Ethylenediaminetetraacetic acid and citric acid appeared to offer greater potentials as chelating agents to use in remediating the high permeability soil. Tartaric acid, however, is recommended in events of moderate contamination.
    International journal of Environmental Science and Technology 06/2010; 7(3). DOI:10.1007/BF03326158 · 1.79 Impact Factor
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    Ekebafe L.O. · Imanah J.E. · Okieimen F.E.
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    ABSTRACT: Samples of rubber seed shells were carbonized at varying temperatures (100, 200, 300, 400, 500, 600, 700 and 800 °C) for three hours each and sieved through a 150 μm screen. The portion of the rubber seed shell carbon that passed through the screen was characterized in terms of loss on ignition, surface area, moisture content, pH, bulk density, and metal content and used in compounding natural rubber. The characterization shows that the pH, conductivity, loss on ignition and the surface area increases with the increases of the heating temperature, unlike the bulk density which decreases. The compound mixes were cured using the efficient vulcanization system. Cure characteristics of compounds and physico-mechanical properties of the vulcanisates were measured as a function of filler loading along with that of N330 carbon-black filled natural rubbers. The results showed that the cure times, scorch times and the torque gradually increased, with increasing the filler content for rubber seed shell carbon-filled natural rubber, with the filler obtained at carbonizing temperature of 600 °C tending to show optimum cure indices. The physicomechanical properties of the vulcanisates increase with filler loading. The reinforcing potential of the carbonized rubber seed shell carbon was found to increase markedly for the filler obtained at the temperature range of 500-600 °C and then decreases with further increase in temperature.
    Chemical Industry and Chemical Engineering Quarterly 04/2010; 16(2). DOI:10.2298/CICEQ091115022E · 0.66 Impact Factor
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    E U Ikhuoria · A S Folayan · F E Okieimen
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    ABSTRACT: Graft copolymers of starch and acrylonitrile were synthesized in aqueous solution. Ceric ammonium ion was used to initiate the graft copolymerization. Ten grades of graft copolymers were synthesized-five by varying the initial concentration of the monomer and the other five by varying the initial concentration of the initiator. Evidence of graft copolymerization of the hydrolyzed products was obtained from the IR analyses. Some grafting parameters such as % grafting ratio and % conversion were favoured by initial increase in the monomer concentration. However, these parameters were observed to decrease at much higher concentrations (>3 M). Evidence of hydrolysis shows that the grafted copolymers could be used as flocculants.
  • T. O. Egbuchunam · F. E. Okieimen · D. B. Balköse
    02/2010; 1:47-56. DOI:10.4028/www.scientific.net/JERA.1.47
  • MALOMO D · A. K. AKINLABI · F. E. OKIEIMEN · EGHAREVBA F
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    ABSTRACT: Blends of natural rubber (NR) and low molecular weight natural rubber (LMWNR) were compounded using three different mixing schemes by adopting the semi-efficient sulphur vulcanization compounding formulation. In scheme 1, the natural rubber and LMWNR were first mixed before adding the compounding ingredients. In scheme 2, the compounding ingredients were first mixed with the NR before adding the LMWNR and in scheme 3 the compounding ingredients were first mixed with the LMWNR before adding the NR. Properties of the vulcanizates from the three mixing schemes viz-a-viz: chemical resistance, ageing and physico-mechanical properties were investigated and compared. The physico-mechanical results of all the vulcanizates were found to be within the accepted level for NR compounds. The ageing results from all the mixing schemes were found impressing. Vulcanizates from mixing scheme 1 restricted penetration of petroleum fuels and organic solvents best, followed by scheme 2 and the least was scheme 3. The activation energy and free energy change were found to be highest with scheme 1, thereby making mixing scheme 1 being more technologically advantageous than other mixing schemes.
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    Malomo D. · Akinlabi A.K. · F. E. Okieimen · F. Egharevba
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    ABSTRACT: Blends of natural rubber (NR) and low molecular weight natural rubber (LMWNR) were compounded using three different mixing schemes by adopting the semi-efficient sulphur vulcanization compounding formulation. In scheme 1, the natural rubber and LMWNR were first mixed before adding the compounding ingredients. In scheme 2, the compounding ingredients were first mixed with the NR before adding the LMWNR and in scheme 3 the compounding ingredients were first mixed with the LMWNR before adding the NR. Properties of the vulcanizates from the three mixing schemes viz-a-viz: chemical resistance, ageing and physico-mechanical properties were investigated and compared. The physico-mechanical results of all the vulcanizates were found to be within the accepted level for NR compounds. The ageing results from all the mixing schemes were found impressing. Vulcanizates from mixing scheme 1 restricted penetration of petroleum fuels and organic solvents best, followed by scheme 2 and the least was scheme 3. The activation energy and free energy change were found to be highest with scheme 1, thereby making mixing scheme 1 being more technologically advantageous than other mixing schemes.
    Chemical Industry and Chemical Engineering Quarterly 01/2010; 16(1):19-30. DOI:10.2298/CICEQ1000001M · 0.66 Impact Factor
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    EG Uwumarongie-Ilori · FE Okieimen
    01/2010; 4(9). DOI:10.4314/ajest.v4i9.71313
  • R.A. Wuana · F.E. Okieimen · S.O. Adejo · P.A. Mbasugh
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    ABSTRACT: Rice husks carbon was prepared and evaluated for the single and competitive aqueous phase adsorption of hardness causing ions. The precursor (rice husks) was ammonium chloride-activated at 30 ± 1oC for 12h followed by carbonization at 350oC for 1h. The portion of carbon that passed through a 300μm sieve and retained on a 90μm sieve was characterized in terms of percent attrition, pH, bulk density, porosity, surface area and total acidic surface groups. The attributes of the rice husk carbon compared favourably with those of a commercial grade carbon (Thermax). Single solute equilibrium adsorption of Ca2+ and Mg2+ ions was satisfactorily described (but more so for Mg2+) by the single component Langmuir, Freundlich and Tempkin isotherms. Ca2+ ion appeared to be more quantitatively adsorbed than Mg2+during competitive adsorption. Better correlations were, however, found between experimental and predicted amounts adsorbed for Mg2+than Ca2+. The adsorption of both ions obeyed pseudo-second order kinetics and followed the intraparticle diffusion mechanism. These findings are of importance to simple water treatment schemes that utilize the principle of activated carbon adsorption. Keywords: Competitive adsorption, rice husk carbon, isotherms, and kinetics.
  • F. E. Okieimen · T. O. Egbuchunam · D. B. Balköse
    Advanced Materials Research 01/2009; 62-64:335-344. DOI:10.4028/www.scientific.net/AMR.62-64.335