Browsing by Author "Oguzie, Emeka Emmanuel"

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    Experimental and DFT evaluation of adsorption and inhibitive properties of Moringa oliefera extract on mild steel corrosion in acidic media
    (Elsevier B. V. on behalf of King Saudi University, 2020-11) Akalezi, Christogonus Oudney; Maduabuchi, Arinze Chidiebere; Eneneneaku, Conrad Kenechukwu; Oguzie, Emeka Emmanuel
    The corrosion response of mild steel in 0.5 M H2SO4 acid solution in the presence of Moringer oliefera (MO) leaf extract was investigated using gravimetric, electrochemical, and DFT techniques. Gravimetric results indicate that MO exhibits a high inhibition value up to 93.0% when the concentration was 1.5 g/L. Inhibition value in general increased with an increase in concentration of the extracts but decreased with prolonged exposure time and temperature. Analysis of polarization curves indicated that MO extract acted as mixed-type inhibitors. The adsorption process of MO on a mild steel surface in the acid solution fitted the Langmuir isotherm. GC/MS analysis of MO extract revealed the presence of more than 29 active constituents including 9,12-Octadecadienoic acid (Z, Z) methyl ester (28.55%); n-Hexadecanoic acid (11.24%); 9,12,15-Octadecatrienoic acid methyl ester (9.31%), Benzeneacetonitrile, 4-hydroxy-(6.32%),2-Furancarboxaldehyde,5-(hydroxymethyl)-(5.6%), Heptadecane (4.85%). Quantum chemical calculations were applied on some of the identified constituents to assess their adsorbability on the mild steel surface and the result revealed remarkable high interaction energies.
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    Inhibition of mild steel corrosion in acidic medium using theobroma cacao pod
    (UP, 2020-03) Izionworu, Vincent Onuegbu; Ukpaka, Chukwuemeka Peter; Oguzie, Emeka Emmanuel
    Corrosion inhibition effect of cold water extract of Theobroma cacao pods - Cocoa pod (TCP-CP) on mild steel corrosion in 1 M HCl base stock solution has been studied. The study was conducted using weight loss measurement narrowed down to the effect of immersion time, inhibitor concentration and temperature on the corrosion behavior of mild steel in 1 M HCl in the absence and presence of TCP-CP. The study also investigated the thermodynamic properties of the inhibitor in the corrodent and revealed that the adsorption of the cold extracts of TCP-CP on mild steel surface was concentration dependent and obeyed Langmuir adsorption isotherm. The equilibrium constant of adsorption process (Kads) for TCP-CP inhibitor evaluated mathematically is 0.00266, 0.0271, 0.1795, 0.0253 and 0.0147 (mg/L) with a free energy of adsorption (∆Goads) value of -0.978, -1.060, -6.173, 0.942 and 0.737 kJ/mol at 303, 313, 323, 333 and 343 K respectively. The small values of Kads suggest weak absorption which is corroborated by the low negative values of the free energy of adsorption, ∆Goads, values obtained from thermodynamic measurements. The negative value of ∆Goads suggests that the adsorption of TCP-CP inhibiting particles on the mild steel surface was favourable from thermodynamic point of view and provided proof that TCP-CP extracted with cold water is an efficient inhibitor and the thermodynamic properties of the examined concentrations determined
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    Photocatalytic degradation of Congo red using doped zinc oxide nanoparticles
    (Alma Mater Studiorum, 2024-02-22) Nwaiwu, Blessing Chidinma; Oguzie, Emeka Emmanuel; Ejiogu, Christopher, Chibuzor
    The photocatalytic degradation of Congo Red (CR) was studied using zinc oxide (ZnO) nanoparticles as catalys (ZC, NZ, AZ and ANZ) under UV light, solar and dark. ZnO nanoparticles were synthesized by one-step liquid impregnation and each nanoparticles was calcined at 60 oC for 4 hours. The UV-vis spectra study assured that the band gap decreased as N and Ag doped to ZnO and hence the absorption band shifts toward the longer wavelength region (red shift). The morphological structures of as-synthesized nanomaterials were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The parameters studied were catalyst dosage and the pH of the reaction mixture. The degradation of the dye was found to be effective in the range; catalyst dose of 0.10, 0.20, 0.30 and 0.4 g ZnO catalyst/100 mL of dye solution, initial concentration 10 mg/L, and pH 8.11. Experimentation on different catalyst dosage of ZnO nanoparticles showed that 0.2 g ZnO catalyst/100 mL with the percentage degradation (ZC 70%, ANZ 99.7%, AZ 92.5%, NZ 85.8%) is the most suitable catalyst dosage for degrading CR under UV irradiation at 120 min of irradiation time. Photocatalytic processes were found to work better in basic condition and the best pH value was 8.0. The results showed that a percentage Congo Red degradation of 99.7% could be obtained when treating an effluent with 10 mg/L of Congo Red for 120 mins at 0.2 g ZnO catalyst/100 mL of effluent and pH 8 under UV irradiation using nitrogen doped silver co-doped zinc oxide, ANZ) both under solar and UV than (NZ) and silver- nitrogen doped zinc oxide (A), this was attributed to the lower rate of recombination of the photo-generated electrons and holes as well as its lower gap energy
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    Unraveling the sorption mechanisms of ciprofloxacin on the surface of zeolite 4A (001) in aqueous medium by DFT and MC approaches
    (Elsevier Ltd, 2024-02) Djioko, Fredy Harcel Kamgang; Fotsop, Cyrille Ghislain, Youbi; Youbi, Georges Kamgang; Nwanonenyi, Simeon, Chukwudozie; Madu, Chinyere Ada; Oguzie, Emeka Emmanuel
    The adsorption mechanism of ciprofloxacin (CIP) and its ionic form were investigated using density functional theory (DFT) and molecular dynamics (MD), with the goal of forecasting their adsorption behavior in terms of gap energy, global reactivity descriptors, Fukui functions, adsorption energies, and density of state on the surface of zeolite 4A (001). Quantum chemical parameters related to the adsorption process were calculated, as well as the overall reactivity. According to DFT calculations, the zwetterionic form CIP± are the most stable and reactive and have a greater power of electron transfer compared to the other species. Under aqueous conditions, zeolite can adsorb ciprofloxacin (CIP) and its ionic forms, as revealed by molecular dynamics simulation. Ciprofloxacin in the zwitterionic form (CIP±) were more efficiently adsorbed to the surface of zeolite 4A (001) than the cationic (CIP+), anionic (CIP−), and neutral(CIP) forms; through the evaluation of adsorption energy, probability distribution, interaction, and density of state. The results also demonstrated that the compounds studied were adsorbed via the process of chemical bonding, which was confirmed by the negative values of the interaction energy. Furthermore, the negative adsorption energy values suggest a significant adsorption of all compounds, with electrostatic interactions (physisorption), diffusion into the pores, and n-π bonds (chemisorption) on the zeolite surface. The increase in adsorption energies and the proximity of the molecules studied to the zeolite surface indicate the predominance of chemisorption, and the adsorption of ciprofloxacin was found to be an exothermic and spontaneous process. Molecular dynamics (MD) modeling was in agreement with the DFT results