Browsing by Author "Njoku, P. C."

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    Adsorption of cupper (II) ion on heterogeneous surfaces of selected low-cost precursors; an application of isotherm, thermodynamic and kinetic models
    (U. P., 2015-01) Uzoije , Atulegwu .Patrick; Okolie, Justus I.; Njoku, P. C.; Enwereuzo., Uzo
    Cupper ions occur naturally in the environment and also prevalent in the waste from metal smelting industries through which it gets to the environment. Excessive intake of cupper results to adverse health effects on plant, animals and humans. The present study therefore studied the Adsorption of Cupper (II) ion on three activated bio-adsorbents; Unripe plantain peel, pineapple peel and commercial activated carbon. The activated carbons were characterized for surface morphology and functional groups for removal of Cupper (II) ion from aqueous solution. Batch process was adopted to study the time, temperature effect and isotherm equilibrium of Cupper (II) ion on. Adsorption of Cupper (II) ion on the three adsorbents got to equilibrium at between 80-100 minutes. Adsorption capacity of the three adsorbent was in this order at all temperature values; Unripe plantain peel greater than pineapple peel and greater than commercial activated carbon. Adsorption of Cupper ion increased with temperature, adsorption got to its plateau at 45oC and began to decrease. Langumuir-freunlich and Dubini-Radushkevichmodels were applied to analyze the Isotherm data. Langumuir-freunlich described the data better than Dubini-Radushkevich. Also, Pseudo-first order, pseudo-second-order, and intra-particle diffusion models were applied to test the kinetic data, pseudo-second-order fitted the data better than pseudo-first order. Pore-pore particle diffusion was observed to be the controlling step. Endothermic and non- spontaneous processes characterized Cupper ion adsorption on the three adsorbents .
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    Novel non-parametric assessment of heavy metals in coated card wastes
    (U. P., 2017-11-09) Nwoko, C. I. A.; Nkwoada, A. U.; Njoku, P. C.; Obichini, A.
    Non-parametric tests were applied for the first time to coated mobile card waste in order to determine the correlation within risk assessment and instrumentation. The AAS concentrations of all the metals were higher than their XRF concentrations except in Al and Ag metals. Cr had the highest distribution pattern while Ag metal had the lowest respectively. The target hazard quotient (THQ) for all metals were below minor hazard level. On the contrary, only Fe and Zn were below the Oral reference dose (RfD) value and the daily metal intake (DMI) respectively. The WilcoxonMann-Whitney test showed no significant difference between the concentration of the metals in XRF and AAS analysis results but identified the unusual behavior of Ag and Al metals; hence it depicted that both AAS and XRF analysis results were not sensitive to detect the different metal concentrations in the cards. Hence, similar coating specifications are utilized. The Kruskal Wallis test and Spearman correlation coefficient showed that the results from AAS and XRF were significantly different. Hence it showed that instrumentation showed sensitivity of metal concentrations from the recharge cards. This correlated with THQ, DMI, health risk index (HRI) risk assessment parameters that different coating specifications were used causing different values at same sampling points. Therefore, the results established that non-parametric tests are good analytical tools.
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    Phytoextraction and risk assessment synergy of three edible plants in mining area
    (U. P., 2018-08-11) Nwoko, C. I. A.; Nkwoada, A. U.; Onu, L. U.; Njoku, P. C.; Ogbonnaya, D. O.
    The phytoextraction and risk assessment synergy of Arachis hypogea (groundnut), Zea maize (Corn) and Citrullus colocynthis L. (Melon) was investigated at a mining area contaminated with Cd, Cu, Pb and Zn heavy metals. The metal concentrations in plant matter and soil were determined using AAS. The average pH at 5.2 showed a slightly acidic soil while the total organic content and electrical conductivity were low. The studied metals exceeded the Nigerian FEPA guidelines as well as EU threshold values at the sites. Increase in Cd concentration in the North and South caused a corresponding decrease in plant yield. The maize appreciably accumulated more Pb than melon and groundnut. The phytoplants at the West sampling point accumulated more Zinc and melon grown at the west accumulated highest zinc concentrations of up to 1100 mg/kg. The Presence of Cu metal at low concentrations favoured an equivalent increase in weight of harvested groundnut seed. The Coefficient of Variation (CV) showed a correlation that hyperaccumulators had equivalent higher CV distribution. The values of Cd, Cu and Pb exceeded the Health Risk Index value of 1 in all the three edible phytoplants. The Cd demonstrated the lowest Bioconcentration Factor of (0.03) within the sampling area, among studied metals and the three edible plants. Thus Target Hazard Quotient (THQ) results agreed with the Daily Intake of Metals (DIM) results, that consumption of any of the three edible plants are unsafe and poses a health risk to locals; hence, the synergy of THQ and DIM in evaluating experimental data is detected in this study.