Activated carbons calcined at 400˚C and 600˚C (AC-400 and AC-600), prepared using palm nuts, collected in the town of Franceville in Gabon, were used to study the dynamic adsorption of MnO<sub>4</sub>-<...Activated carbons calcined at 400˚C and 600˚C (AC-400 and AC-600), prepared using palm nuts, collected in the town of Franceville in Gabon, were used to study the dynamic adsorption of MnO<sub>4</sub>-</sup> ions in acidic media on fixed bed column and on the kinetic modeling of experimental data of breakthrough curves of MnO<sub>4</sub>-</sup> ions obtained. Results on the adsorption of MnO<sub>4</sub>-</sup> ions in fixed-bed dynamics obtained on AC-400 and AC-600 adsorbents beds indicated that the AC-400 bed appears to be the most efficient in removing MnO<sub>4</sub>-</sup> ions in acidic media. Indeed, the adsorbed amounts, the adsorbed capacities at saturation and the elimination percentage of MnO<sub>4</sub>-</sup> ions obtained with AC-400 (31.24 mg;52.06 mg·g<sup>-1</sup> and 41.65% respectively) were higher compared to those obtained with AC-600 (9.87 mg;16.45 mg·g<sup>-1</sup> and 17.79% respectively). The breakthrough curves kinetic modeling revealed that the Thomas model and the pseudo-first-order kinetic model were the most suitable models to describe the adsorption of MnO<sub>4</sub>-</sup> ions on adsorbents studied in our experimental conditions. The results of the intraparticle diffusion model showed that intraparticle diffusion was involved in the adsorption mechanism of MnO<sub>4</sub>-</sup> ions on investigated adsorbents and was not the limiting step and the only process controlling MnO<sub>4</sub>-</sup> ions adsorption. In contrast to AC-400, the intraparticle diffusion on AC-600 bed plays an important role in the adsorption mechanism of MnO<sub>4</sub>-</sup> ions.展开更多
The reaction abilities of structural units in Fe-C binary melts over a temperature range above the liquidus lines have been evaluated by a thermodynamic model for calculating the mass action concentrations Ni of struc...The reaction abilities of structural units in Fe-C binary melts over a temperature range above the liquidus lines have been evaluated by a thermodynamic model for calculating the mass action concentrations Ni of structural units in Fe-C binary melts based on the atom-molecule coexistence theory （AMCT）, i.e., the AMCT-N/model, through comparing with the predicted activities aR.i of both C and Fe by 14 collected models from the literature at four temperatures of 1833, 1873, 1923, and 1973 K. Furthermore, the Raoultian activity coefficient γC0 of in infinitely dilute Fe-C binary melts and the standard molar Gibbs free energy change △solG%m,Cdis（1）→[C]W[C]=1.0 of dissolved liquid C for forming w[C] as 1.0 in Fe-C binary melts referred to 1 mass% of C as reference state have also been determined to be valid. The determined activity coefficient In γC of C and activity coefficient In TEe of Fe including temperature effect for Fe-C binary melts can be described by a quadratic polynomial function and a cubic polynomial function, respectively.展开更多
文摘Activated carbons calcined at 400˚C and 600˚C (AC-400 and AC-600), prepared using palm nuts, collected in the town of Franceville in Gabon, were used to study the dynamic adsorption of MnO<sub>4</sub>-</sup> ions in acidic media on fixed bed column and on the kinetic modeling of experimental data of breakthrough curves of MnO<sub>4</sub>-</sup> ions obtained. Results on the adsorption of MnO<sub>4</sub>-</sup> ions in fixed-bed dynamics obtained on AC-400 and AC-600 adsorbents beds indicated that the AC-400 bed appears to be the most efficient in removing MnO<sub>4</sub>-</sup> ions in acidic media. Indeed, the adsorbed amounts, the adsorbed capacities at saturation and the elimination percentage of MnO<sub>4</sub>-</sup> ions obtained with AC-400 (31.24 mg;52.06 mg·g<sup>-1</sup> and 41.65% respectively) were higher compared to those obtained with AC-600 (9.87 mg;16.45 mg·g<sup>-1</sup> and 17.79% respectively). The breakthrough curves kinetic modeling revealed that the Thomas model and the pseudo-first-order kinetic model were the most suitable models to describe the adsorption of MnO<sub>4</sub>-</sup> ions on adsorbents studied in our experimental conditions. The results of the intraparticle diffusion model showed that intraparticle diffusion was involved in the adsorption mechanism of MnO<sub>4</sub>-</sup> ions on investigated adsorbents and was not the limiting step and the only process controlling MnO<sub>4</sub>-</sup> ions adsorption. In contrast to AC-400, the intraparticle diffusion on AC-600 bed plays an important role in the adsorption mechanism of MnO<sub>4</sub>-</sup> ions.
基金This work is supported by the Beijing Natural Science Foundation （Grant No. 2182069） and the National Natural Science Foundation of China （Grant No. 51174186）.
文摘The reaction abilities of structural units in Fe-C binary melts over a temperature range above the liquidus lines have been evaluated by a thermodynamic model for calculating the mass action concentrations Ni of structural units in Fe-C binary melts based on the atom-molecule coexistence theory （AMCT）, i.e., the AMCT-N/model, through comparing with the predicted activities aR.i of both C and Fe by 14 collected models from the literature at four temperatures of 1833, 1873, 1923, and 1973 K. Furthermore, the Raoultian activity coefficient γC0 of in infinitely dilute Fe-C binary melts and the standard molar Gibbs free energy change △solG%m,Cdis（1）→[C]W[C]=1.0 of dissolved liquid C for forming w[C] as 1.0 in Fe-C binary melts referred to 1 mass% of C as reference state have also been determined to be valid. The determined activity coefficient In γC of C and activity coefficient In TEe of Fe including temperature effect for Fe-C binary melts can be described by a quadratic polynomial function and a cubic polynomial function, respectively.
