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S.A. Umoren,I.B. Obot,AU Israel,P.O. Asuquo,M.M. Solomon,UM Eduok,A.P. Udoh 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5
Corrosion inhibition of mild steel in H2SO4 by water and methanol extracts of coconut coir dust was studied using chemical and electrochemical techniques. It was found that the extracts inhibited the acid induced corrosion of mild steel. The inhibition efficiency increased with increase in extracts concentration but decreased with increase in temperature. Methanol extract was found to be a better inhibitor. The adsorption of the extracts’ components onto the mild steel surface follow Temkin and Freundlich adsorption isotherms for methanol and water extracts respectively. Polarization studies show that the extracts act as mixed typed inhibitor but under cathodic control.
Effect of halide ions on the corrosion inhibition efficiency of different organic species – A review
S.A. Umoren,M.M. Solomon 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1
The influence of halide ions (Cl , Br , I ) on the corrosion inhibition efficiencies of various organic-typeinhibitors including polymers, natural products of plant origin, organic dyes, surfactants, drugs etc. onmetals corrosion in various aqueous aggressive environments and under different experimentalconditions has been widely reported in the literature and is discussed in this paper. Most of the availabledata show that the halide additives synergistically increased the inhibition efficiencies of most organiccation-type molecules in the order Cl < Br < I in the different environments investigated. Suchsynergistic effects often show sensitivity to various factors including nature and concentration of theadditives, temperature as well as nature of the metal and aggressive environments. Mechanismsproposed for the synergistic interactions have been compared and evaluated with respect to the reportedexperimental data.
Utilization of watermelon rind extract as a green corrosion inhibitor for mild steel in acidic media
N.A. Odewunmi,S.A. Umoren,Z.M. Gasem 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1
Electrochemical techniques were used to investigate the efficacy of watermelon rind extract (WMRE) ascorrosion inhibitor for mild steel in HCl and H2SO4 solutions. The inhibition efficiency increased as theconcentration of the extract increases. Potentiodynamic polarization results indicate that WMRE act as amixed-type inhibitor. The values of effective capacitance obtained by utilizing the impedanceparameters in both acidic media are in the range of double layer capacitance. Corrosion inhibition effectof WMRE can be attributed to the adsorption of constituents of WMRE onto the mild steel surface whichcan be approximated by Temkin adsorption isotherm model.
Ubong Eduok,E. Inam,S.A. Umoren,I.A. Akpan 한국자원공학회 2013 Geosystem engineering Vol.16 No.2
The inhibition of a substituted naphthol compound, 4-(4-nitrophenylazo)-1-naphthol (44NIN), on the corrosion of aluminium (Al) in a basic medium was studied by classical chemical (gravimetric) and spectrophotometric (UV–Vis and FTIR) methods at 303–333 K. 44NIN demonstrated an excellent inhibiting property to Al corrosion in the aerated binary alkaline solution as shown from the results. The inhibition efficiency was found to increase with the azo dye concentration but not with temperature. Thermodynamic and adsorption evaluation for this inhibition process were accessed and thoroughly discussed. The UV–visible absorption spectra of the solution containing this dye after the immersion of Al specimen indicate the possible formation of a 44NIN–Fe type complex. The FTIR was carried out of the dye and protective film formed on the surface of the metal in the electrolyte containing the dye after a 72 h immersion period. These results show a correlation between the inhibitive effect and molecular structural information of 44NIN in this typical heterogeneous alkaline system.
I.B. Obot,S.A. Umoren,Z.M. Gasem,Rami Suleiman,Bassam El Ali 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1
Corrosion inhibition potentials of two imidazole derivatives namely, vinylimidazole (VI) andallylimidazole (AI) for carbon steel in 1M HCl at 25 C were predicted theoretically using quantumchemical calculations and molecular dynamics (MD) simulations. DFT calculations indicated that VI ismore reactive towards steel surface than AI. Equilibruim adsorption behaviour of VI and AI molecules onFe2O3 (010) surface was investigated using molecular dynamics (MD) simulations. The equilibriumadsorption energy followed the order: VI > AI. Theoretical conclusions were subsequently validatedexperimentally using potentiodynamic polarization, linear polarization resistance, electrochemicalimpedance spectroscopy, and surface analytical techniques (SEM and AFM).