In this study, the adsorption kinetics, equilibrium and thermodynamics of Fe3+ ions on natural (NAP) and synthetic (HAP) apaties were examined. The adsorption efficiency of Fe3+ onto the NAP and HAP was increased with...In this study, the adsorption kinetics, equilibrium and thermodynamics of Fe3+ ions on natural (NAP) and synthetic (HAP) apaties were examined. The adsorption efficiency of Fe3+ onto the NAP and HAP was increased with increasing temperature. The kinetics of adsorption of Fe3+ ions was discussed using three kinetic models, the pseudo-first-order, the pseudo-second-order and the intra-particle diffusion model. The experimental data fitted very well the pseudo-second-order kinetic model. The initial sorption rate and the activation energy were also calculated. The activation energy of the sorption was calculated as 37.15 and 49.84 kJ·mol 1 for NAP and HAP, respectively. Experimental results were also analysed by the Langmuir, Freundlich and Dubinin–Redushkevich (D–R) isotherm equations at different temperatures. RL separation factor for Langmuir and the n value for Freundlich isotherm show that Fe3+ ions are favorably adsorbed by NAP and HAP. Various thermodynamic parameters such as enthalpy (ΔH), Gibbs free energy (ΔG) and entropy (ΔS) changes were computed and the results showed that the adsorption of Fe3+ ions onto NAP and HAP were spontaneous and endothermic in nature.展开更多
The stability of three asphaltene-hydrogen donor systems,namely asphaltene-1-methylnaphthalene,asphaltene-tetralin,and asphaltene-decalin,with a mass ratio of 1:10 was investigated using the Turbiscan stability analyz...The stability of three asphaltene-hydrogen donor systems,namely asphaltene-1-methylnaphthalene,asphaltene-tetralin,and asphaltene-decalin,with a mass ratio of 1:10 was investigated using the Turbiscan stability analyzer.The interactions between hydrogen donor molecules and asphaltene units were simulated and calculated using Gaussian and Multiwfn,and then,noncovalent interaction analysis was performed.The results showed that the stability of the three asphaltene-hydrogen donor systems decreased as follows:asphaltene-1-methylnaphthalene>asphaltene-tetralin>asphaltene-decalin.The stability differences among the three systems were due to the different interactions between the hydrogen donor molecules and the asphaltene unit.The T-stacking interaction strength between the hydrogen donor molecules and the asphaltene units decreased as follows:1-methylnaphthalene-asphaltene unit>tetralin-asphaltene unit>decalin-asphaltene unit.Qualitative analysis indicates that the T-stacking interactions between the hydrogen donor molecules and the asphaltene units were mainly van der Waals forces,and the proportions of hydrogen bonds in the weak interaction differed among the systems.展开更多
文摘In this study, the adsorption kinetics, equilibrium and thermodynamics of Fe3+ ions on natural (NAP) and synthetic (HAP) apaties were examined. The adsorption efficiency of Fe3+ onto the NAP and HAP was increased with increasing temperature. The kinetics of adsorption of Fe3+ ions was discussed using three kinetic models, the pseudo-first-order, the pseudo-second-order and the intra-particle diffusion model. The experimental data fitted very well the pseudo-second-order kinetic model. The initial sorption rate and the activation energy were also calculated. The activation energy of the sorption was calculated as 37.15 and 49.84 kJ·mol 1 for NAP and HAP, respectively. Experimental results were also analysed by the Langmuir, Freundlich and Dubinin–Redushkevich (D–R) isotherm equations at different temperatures. RL separation factor for Langmuir and the n value for Freundlich isotherm show that Fe3+ ions are favorably adsorbed by NAP and HAP. Various thermodynamic parameters such as enthalpy (ΔH), Gibbs free energy (ΔG) and entropy (ΔS) changes were computed and the results showed that the adsorption of Fe3+ ions onto NAP and HAP were spontaneous and endothermic in nature.
文摘The stability of three asphaltene-hydrogen donor systems,namely asphaltene-1-methylnaphthalene,asphaltene-tetralin,and asphaltene-decalin,with a mass ratio of 1:10 was investigated using the Turbiscan stability analyzer.The interactions between hydrogen donor molecules and asphaltene units were simulated and calculated using Gaussian and Multiwfn,and then,noncovalent interaction analysis was performed.The results showed that the stability of the three asphaltene-hydrogen donor systems decreased as follows:asphaltene-1-methylnaphthalene>asphaltene-tetralin>asphaltene-decalin.The stability differences among the three systems were due to the different interactions between the hydrogen donor molecules and the asphaltene unit.The T-stacking interaction strength between the hydrogen donor molecules and the asphaltene units decreased as follows:1-methylnaphthalene-asphaltene unit>tetralin-asphaltene unit>decalin-asphaltene unit.Qualitative analysis indicates that the T-stacking interactions between the hydrogen donor molecules and the asphaltene units were mainly van der Waals forces,and the proportions of hydrogen bonds in the weak interaction differed among the systems.
