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Browsing Research Articles by Subject "Activated carbon"

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    Equilibrium, thermodynamic and kinetic studies on adsorption of zinc (II) from solutions using different low-cost adsorbents
    (Open Science, 2015-11-05) Njoku, Pascal C.; Atu, A. Ayuk; Atulegwu, P. Uzoije; Justus I. Okolie
    Many industrial wastewaters contain numerous toxic metals such as zinc, which must be removed before reuse of the water or discharge into the environment. In this present study, unripe plantain peel activated carbon (UPPAC), pineapple peel activated carbon (PPAC) and commercial activated carbon (CAC) were utilized as low cost adsorbents for the removal of Zn (II) from aqueous solutions. Batch adsorption methodology was used to evaluate the effect of solution pH, initial metal ion concentration, adsorbent dose, contact time and temperature on adsorption. Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectrophotometer (FTIR) were used to characterize the adsorbents. The equilibrium isotherm data were analyzed using the Langmuir, Freundlich and Temkin isotherm model. The kinetic data were analyzed using the pseudo-first order, pseudo-second order equations, Elovich equation and intraparticle rate equation. Maximum adsorption of Zn (II) on UPPAC, PPAC and CAC (82.45%, 89.95% and 93.45%) was observed at pH 6 and pH 7. The adsorbed amount of Zn (II) increased with increase in contact time and reached equilibrium within 180 minutes. The maximum adsorption was found to be 200 mg/L in the studied range (200 – 1000 mg/L). The adsorption capacity and percent removal of Zn (II) were found to increase with increase in temperature. The Freundlich isotherm models provided the best fit to the experimental data for Zn (II) as indicated by the regression coefficient values (R2> 0.97). The pseudo-second order equation gave the best fit to the experimental data for the metal ion (R2 > 0.99). Thermodynamic analysis showed a spontaneous adsorption process as negative values of ∆Go (-1.269 to -5.530) were obtained at all temperatures. The positive enthalpy change ∆Ho, 18.00, 20.46 and 23.45 kJ mol-1 for UPPAC, PPAC and CAC indicated an endothermic process. A highly disordered process was indicated by the positive entropy change ∆So .
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    ItemOpen Access
    Equilibrium, thermodynamic and kinetic studies on adsorption of zinc (II) from solutions using different low-cost adsorbents
    (U. P., 2015) Njoku, Pascal C.; Ayuk, Atu A.; Uzoije, Atulegwu, P.; Okolie, Justus I.
    Many industrial wastewaters contain numerous toxic metals such as zinc, which must be removed before reuse of the water or discharge into the environment. In this present study, unripe plantain peel activated carbon (UPPAC), pineapple peel activated carbon (PPAC) and commercial activated carbon (CAC) were utilized as low cost adsorbents for the removal of Zn (II) from aqueous solutions. Batch adsorption methodology was used to evaluate the effect of solution pH, initial metal ion concentration, adsorbent dose, contact time and temperature on adsorption. Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectrophotometer (FTIR) were used to characterize the adsorbents. The equilibrium isotherm data were analyzed using the Langmuir, Freundlich and Temkin isotherm model. The kinetic data were analyzed using the pseudo-first order, pseudo-second order equations, Elovich equation and intraparticle rate equation. Maximum adsorption of Zn (II) on UPPAC, PPAC and CAC (82.45%, 89.95% and 93.45%) was observed at pH 6 and pH 7. The adsorbed amount of Zn (II) increased with increase in contact time and reached equilibrium within 180 minutes. The maximum adsorption was found to be 200 mg/L in the studied range (200 – 1000 mg/L). The adsorption capacity and percent removal of Zn (II) were found to increase with increase in temperature. The Freundlich isotherm models provided the best fit to the experimental data for Zn (II) as indicated by the regression coefficient values (R2 > 0.97). The pseudo-second order equation gave the best fit to the experimental data for the metal ion (R2 > 0.99). Thermodynamic analysis showed a spontaneous adsorption process as negative values of ∆Go (-1.269 to -5.530) were obtained at all temperatures. The positive enthalpy change ∆Ho, 18.00, 20.46 and 23.45 kJ mol-1 for UPPAC, PPAC and CAC indicated an endothermic process. A highly disordered process was indicated by the positive entropy change ∆So.
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    Microbial assessment of grey water samples treated with activated carbon forms of selected agro-wastes
    (UP, 2020-10-26) Nduka, Chidimma Adamma; Okereke, Josephat Nwabueze; Chukwudi, Peter
    This study evaluated the efficacy of activated carbon from rice husk, corn cob and coconut husk wastes in the reduction of microbial properties of grey water samples harvested from students’ hostels. Microscopic characterization, enumerations and identification of microbial isolates were carried out to determine the microbial community before and after the treatment with activated carbon. Staphylococcus sp, Micrococcus sp, Bacillus sp, Salmonella sp, Saccharomyces sp and Penicillium sp were observed to be present in the grey water. Before treatment, Total Heterotrophic Count (THC) was 1.2 x 1011cfu/ml, Total Coliform Count (TCC), 6.4 x 106cfu/ml and Total Fungi Count (TFC) 2.2 x 1010cfu/ml. THC after the treatment ranged from 1.69 x 109 - 7.6 x 1010cfu/ml; TCC, 2.2 x 105 - 7.3 x 108cfu/ml and TFC 1.0 x 108 - 1.2 x 109cfu/ml. Reduction in the microbial load after treatment revealed that activated carbons from rice husk, corn cob and coconut husk can be used singly or in combined states for the treatment of wastewater.
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    Removal of phenol and selected anions from refinery wastewater using activated carbon from selected agrowastes
    (U. P., 2019-11) Okereke, J. N.; Iloegbunam, C. A.
    Refinery wastewater was treated with activated carbon from rice husk (ARH) and corn cob (ACC) using batch method. Agrowastes were carbonized at 600oC and chemically activated, using phosphoric acid (H3PO4) and used as adsorbents. Titrimetric and spectrophotometeric methods were adopted for the determination of phenol, and some anions (Phosphate, Nitrate – Nitrogen, Sulphate and pH) of refinery wastewater. Readings after treatment with the adsorbents were also recorded and the efficiencies of the adsorbents compared, to ascertain the dose at which purification was best achieved. Initial phenol concentration of 315.9 mg/l was reduced to 159.0±48.0 - 276.5±46.0 mg/l (ARH), 154.7±50,0 - 260.2±53.0 mg/l (ACC) and 132.5±21.0 - 201.9±1.0 mg/l (ARH + ACC). The efficiencies of the activated carbon were of the order: Rice husk + corn cob > rice husk > corn cob, while the corresponding dose efficiencies was: 15g >10g > 5g. The highest adsorption efficiency observed for anions were COD (49.15% by corn cob), BOD, (49.4% by corn cob), phosphate, (68.18% by Rice husk + corn cob), nitrate (70.68% by rice husk) and sulphate (56.68% by corn cob). Efficiency removal was in this order: Rice husk + corn cob > corn cob > rice husk and 15g >10g > 5g for the dosage. There was significant difference (p≤0.05) between the untreated and the treated refinery wastewater samples and a significant difference also exists between the adsorbents. Findings herein showed that activated rice husks and corn cobs are effective in adsorbing phenol and selected anions in refinery wastewater