Browsing by Author "Yunusa, Umar"

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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.
Hexavalent chromium removal from simulated wastewater using biomass-based activated carbon: kinetics, mechanism, thermodynamics and regeneration studies
(جامعة الوادي - university of el oued, 2021-01-21) Yunusa, Umar; Kubo, Abdulrahman Ibrahim; Abdullahi, Yusuf; Abdullahi, Tahir; Husaini, Musa
In this study, activated carbon (ACBA) was fabricated from Balanites aegyptiaca seed shell (BASS) using a two-step H3PO4 activation approach and was tested for the adsorption of toxic hexavalent chromium [Cr(VI)] from simulated wastewater. The surface properties, morphology, and elemental composition of the prepared ACBA were examined via Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) surface area analyses. The influence of various operating conditions such as pH, adsorbent amount, contact time and temperature was investigated. Kinetic studies indicated that the pseudo second order model was able to provide a realistic description of the adsorption kinetics and that film diffusion was the dominating mechanism of the sorption process. The adsorption activation energy evaluated using kinetic data suggested physical nature of Cr(VI) adsorption onto the carbon surface. Thermodynamic investigation confirmed that the adsorption was spontaneous and endothermic in nature. Regeneration tests demonstrated that 0.2 M NaOH can appreciably desorb Cr(VI) from Cr(VI)-loaded ACBA and the regenerated adsorbent can be used for six successive adsorption-desorption cycles while sustaining an adsorption efficiency of 80.10%. Altogether, the ACBA showed high adsorptive performance, fast kinetics and reuse potential, indicating the suitability of its application in wastewater treatment
Kinetic and thermodynamic studies of malachite green adsorption using activated carbon prepared from desert date seed shell
(جامعة الوادي - university of el oued, 2020-01-30) Yunusa, Umar; Usman , ,Bishir; . Ibrahim, . Ibrahim, Muhammad Bashir Muhammad Bashir
The negative effect of high concentration of dyes in the aquatic environment on humans and aquatic plants prompted this research. The adsorption of hazardous malachite green (MG) from aqueous solution using activated carbon derived from desert date seed shell (DDAC) was examined. Batch equilibrium technique was employed to study the effect of contact time (5-120 min), initial concentration (20-100 mg dm-3) and temperature (303.15-333.15 K) on the adsorption capacity of the prepared adsorbent. Experimental data were analyzed using five kinetic models: pseudo-first-order, pseudo-second-order, Elovich, intraparticle diffusion and Boyd models and it was found that the pseudo-second-order model fitted the adsorption data most with the highest correlation (R2 = 0.9999). The overall adsorption process appears to be jointly controlled by intraparticle diffusion and film diffusion mechanisms. Studies of thermodynamic behavior revealed negative values for ΔG (-11.45 to -13.42 kJ mol-1), and a positive value for ΔH (8.39 kJ mol-1) and ΔS (0.065 kJ mol-1 K-1). These indicated the feasibility, endothermicity and spontaneity of the removal process. The results demonstrated that the adsorbent could be exploited in the removal of MG from aqueous solution.