Browsing by Author "Usman, Bishir"

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Corrosion inhibition of aluminium in phosphoric acid solution using glutaraldehyde as inhibitor
(جامعة الوادي - university of el oued, 2020-08-15) Husaini, Musa; unusa, Umar; Ibrahim, Hussaina Aminu; Usman, Bishir; Ibrahim, Muhammad Bashir
The effect of glutaraldehyde as corrosion inhibitor for aluminum in phosphoric acid solution was studied by using weight loss method and characterized by fourier transform infrared spectroscopic and scanning electron microscopic analysis. The inhibition efficiency increases with increase in inhibitor concentration and decreases with increase in temperature while the corrosion rates increases with rise in temperature and decreases with increase in inhibitor concentration. The value of activation energy (ΔEa) was found to be 32.61 kJ/mol in uninhibited acid solution and increased to 47.33 kJ/mol in the presence of 0.1 M inhibitor concentration. The positive values of the enthalpy of activation (ΔHa) suggest an endothermic nature of the reaction and negative values of activation entropy (ΔSa) shows that the activation complexes in the rate determining step represent an association rather than dissociation. The values of free energies of adsorption were all negative which indicate spontaneity of the process. The phenomenon of physical adsorption is proposed from the values of activation energy and free energy of adsorption. The results also shows that the adsorption of inhibitor molecules on the surface of aluminum is accord with Langmuir adsorption isotherm as to the values of correlation coefficient (R2) obtained were very close to unity. The result of the SEM analysis in the presence of inhibitor shows how the aluminium surface was protected against the aggressive effect of the acid. The new functional group in the FTIR analysis of the corrosion product is an indication of thin layer formation on the aluminium surface.
Experimental and quantum chemical investigation for the single and competitive adsorption of cationic dyes onto activated carbon
(جامعة الوادي - university of el oued, 2021-01-04) Yunusa, Umar; Usman, Bishir; Ibrahim, Muhammad Bashir
Single and competitive adsorption studies were performed to scrutinize the removal of two cationic dyes, namely, crystal violet (CV) and malachite green (MG) by adsorption onto activated carbon (BAC) derived from Balanites aegyptiaca seed shell. The BAC was characterized via scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and pH of point of zero charge (pHpzc) analysis. The physicochemical parameters influencing the adsorption process, namely, pH, contact time, adsorbent weight, initial concentration, temperature and ionic strength were examined. Moreover, Density Functional Theory (DFT) studies were performed to investigate the chemical reactivity of the dye molecules. Experimental results indicated that maximum adsorption of both dyes was achieved at pH 8.0 and equilibrium was attained after contact time of 50 min for MG and 60 min for CV. The competitive adsorption results showed lower adsorption capacities as compared to the single adsorption results indicating antagonistic interaction. Isotherm and kinetic models were employed for fitting the experimental data. The sorption kinetics was found to obey the pseudo second order model. The equilibrium data suggests that Freundlich model could represent the dyes uptake onto the adsorbent. Thermodynamic analysis revealed that the adsorption is a spontaneous and endothermic process. The quantum chemical investigation performed on the tested dyes using DFT method have affirmed that the MG molecules are more reactive (ΔE = 1.236 eV), electrophilic and have the capacity to adsorb strongly on the BAC surface compared to the CV (ΔE = 1.476 eV). The results attested that BAC has great potential for cationic dyes adsorption from aqueous environment
Experimental and quantum chemical investigation for the single and competitive adsorption of cationic dyes onto activated carbon
(جامعة الوادي - university of el oued, 2021-01-04) Yunusa, Umar; Usman, Bishir; Ibrahim, Muhammad Bashir
Single and competitive adsorption studies were performed to scrutinize the removal of two cationic dyes, namely, crystal violet (CV) and malachite green (MG) by adsorption onto activated carbon (BAC) derived from Balanites aegyptiaca seed shell. The BAC was characterized via scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and pH of point of zero charge (pHpzc) analysis. The physicochemical parameters influencing the adsorption process, namely, pH, contact time, adsorbent weight, initial concentration, temperature and ionic strength were examined. Moreover, Density Functional Theory (DFT) studies were performed to investigate the chemical reactivity of the dye molecules. Experimental results indicated that maximum adsorption of both dyes was achieved at pH 8.0 and equilibrium was attained after contact time of 50 min for MG and 60 min for CV. The competitive adsorption results showed lower adsorption capacities as compared to the single adsorption results indicating antagonistic interaction. Isotherm and kinetic models were employed for fitting the experimental data. The sorption kinetics was found to obey the pseudo second order model. The equilibrium data suggests that Freundlich model could represent the dyes uptake onto the adsorbent. Thermodynamic analysis revealed that the adsorption is a spontaneous and endothermic process. The quantum chemical investigation performed on the tested dyes using DFT method have affirmed that the MG molecules are more reactive (ΔE = 1.236 eV), electrophilic and have the capacity to adsorb strongly on the BAC surface compared to the CV (ΔE = 1.476 eV). The results attested that BAC has great potential for cationic dyes adsorption from aqueous environment.