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Browsing STEM by Subject "ACE: Future Energies and Electrochemical Systems"

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    Electrochemical and Computational Insights on the Application of Expired Metformin Drug as a Novel Inhibitor for the Sweet Corrosion of C1018 Steel
    (ACS Omega, 2020) Onyeachu, Ikenna B.; Abdel-Azeim, Safwat; Chauhan, Dheeraj Singh
    An expired metformin drug (MET) was used as a corrosion inhibitor for C1018 carbon steel in a CO2-saturated 3.5 wt % NaCl + 340 ppm acetic acid solution under static conditions. The inhibitor was evaluated using electrochemical methods complemented with surface analytical measurements and computa tional modeling. The drug displayed a high inhibition efficiency of ∼90% at 200 ppm. Impedance analyses revealed a rise in the charge transfer resistance at the steel−solution interface upon the addition of the inhibitor. Polarization measurements suggested that MET acted more like a cathodic-type corrosion inhibitor and significantly reduced the corrosion current density. The adsorption of MET on the steel substrate followed the Langmuir isotherm, showing a mixed type of physical and chemical modes of adsorption. The thermodynamic parameters revealed strong and spontaneous adsorption on the steel surface. The surface analysis using SEM supported the inhibitor adsorption on the steel substrate. Based on the DFT simulation, inhibition by MET is mainly achieved by its protonated form, which leads to the formation of a thin film on the steel surface rather than the modification of the work function of the steel surface. The experimental and theoretical estimations of pKa complemented the DFT results, both agreeing that the monoprotonated form of MET is the dominant form in which the inhibitor adsorbs on the steel surface to form a thin film rather than modify the work function of the steel surface
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    Experimental and DFT evaluation of adsorption and inhibitive properties of Moringa oliefera extract on mild steel corrosion in acidic media
    (Arabian Journal of Chemistry, 2020-11) Akalezi, Christogonus Oudney; Maduabuchi, Arinze Chidiebere; Enenebeaku, Conrad Kenechukwu
    he 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. Anal ysis 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-Furancar boxaldehyde,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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    Preliminary Experimental Study of a Single Slope-Double Effect Solar Still Incorporating a Phase Change Material
    (International Journal of Advanced Engineering Research and Science (IJAERS), 2021-05) Nwosu, Ernest Chidi; Nsofor, Kelechi; Nwaji, Godswill N.
    he performance of a double effect solar distillation unit incorporating a paraffin wax has been studied experimentally under the climatic conditions of Owerri, South-East Nigeria. The system comprises double basins with an absorber area of 1.10m2 and a saline water storage tank. It was positioned in the North-South direction with both upper and lower glazings inclined at the latitude of the study location. Performance evaluation of the system was conducted for an extended period of time, capturing both diurnal and nocturnal phases of the system’s operation. The hourly distillate yields of the upper and lower basins were compared. The lower basin performed better than the upper basin during diurnal phase. The diurnal distillate yield of the system ranged from 0.415L to 0.741L for the lower basin and zero to 0.025L for the upper basin. The system achieved a maximum distillate yield rate of 0.21 L/h and an average efficiency of 11.71%.