The adsorption isotherms of caffeine from aqueous solution onto three hydrogen donating adsorbents - hydroxypolystyrene. polystyrene-azo-pyrogallol, and D72 resin-were measured. The adsorption enthalpies calculated fr...The adsorption isotherms of caffeine from aqueous solution onto three hydrogen donating adsorbents - hydroxypolystyrene. polystyrene-azo-pyrogallol, and D72 resin-were measured. The adsorption enthalpies calculated from the isotherms according to the Clausius-Clapeyron equation were-24~ -36kJ/mol, -32~ -37kJ/mol. and -19~ -24kJ/mol respectively These values implied that the absorption processes were based on hydrogen bonding. Furthermore, the mechanism of the adsorption of caffeine onto D72 resin was studied by IR spectra and the small molecular model experiments. and the results showed that the adsorption of caffeine onto hydrogen donating adsorbents was based on hydrogen bonding.展开更多
A strongly hydrophilic hydrogen-bonding adsorbent-macroporous crosslinked poly(N- vinyl-acetamide). which contain both hydrogen bond acceptor and donator, was synthesized. Adsorption mechanism and dynamic adsorption o...A strongly hydrophilic hydrogen-bonding adsorbent-macroporous crosslinked poly(N- vinyl-acetamide). which contain both hydrogen bond acceptor and donator, was synthesized. Adsorption mechanism and dynamic adsorption of tannin from aqueous solution onto the adsorbent were investigated. Most of the differential adsorption heats for various adsorption capacities calculated from the adsorption isotherms according to Clapeyron-Clausius equation lay in the range of hydrogen bond energy (8-50kJ/mol). Adsorption properties of the adsorbent were studied in detail. These results revealed a hydrogen bonding mechanism of the adsorption of tannin from aqueous solution onto the adsorbent. The result of the dynamic adsorption of tanning with the initial concentration under 600 mg/L showed that the adsorption rate of tannin exceeded 90% when the flow rate was 3BV/h and the effluent volume reached 100 BV. Therefore, the developed hydrogen-bonding adsorbent--macroporous crosslinked poly(N-vinyl-acetamide)—is an excellent adsorbent to remove tannin from extract of natural products. and has great value in application.展开更多
The interaction between a gas molecule and photocatalyst is vital to trigger photocatalytic reaction.The surface state of photocatalyst affects much in this interaction.Herein,adsorption of H2O molecules on s-triazine...The interaction between a gas molecule and photocatalyst is vital to trigger photocatalytic reaction.The surface state of photocatalyst affects much in this interaction.Herein,adsorption of H2O molecules on s-triazine-based g-C3N4 was thoroughly studied by first-principle calculation.Although various initial adsorption models with multifarious locations of H2O molecules were built,the optimized models with strong adsorption energy pointed to the same adsorption configuration,in which the H2O molecule hold an upright orientation above the corrugated g-C3N4 monolayer.An intermolecular O-H…N hydrogen bond formed via the binding of a polar O-H bond in H2O molecule and a two-coordinated electron-rich nitrogen atom in g-C3N4.Under the bridging effect of this intermolecular hydrogen bond,electrons would transfer from g-C3N4 to the H2O molecule,thereby lowering the Fermi level and enlarging work function of g-C3N4.Interestingly,regardless of the substitute,i.e.g-C3N4 multilayer,large supercell and nanotube,this adsorption system was highly reproducible,as its geometry structure and electronic property remained unchanged.In addition,the effect of nonmetal element doping on adsorption energy was explored.This work not only disclosed a highly preferential H2O adsorbed g-C3N4 architecture established by intermolecular hydrogen bond,but also contributed to the deep understanding and optimized design in water-splitting process on g-C3N4-based photocatalysts.展开更多
Two hydrogen-bonding adsorbents-macroporous crosslinked poly(p-nitrostyrene) and poly(p-vinylbenzyl amide)--were synthesized, and the absorption property of phenol from cyclohexane solution onto the adsorbents was stu...Two hydrogen-bonding adsorbents-macroporous crosslinked poly(p-nitrostyrene) and poly(p-vinylbenzyl amide)--were synthesized, and the absorption property of phenol from cyclohexane solution onto the adsorbents was studied. The differential adsorption heats for varied adsorption capacities calculated from the adsorption isotherms according to the Clapeyron-Clausius equation lay in the range of hydrogen bond energy (8-50kJ/mol). The adsorption capacity of o-nitrophenol in cyclohexane was much less than that of phenol under the same condition. The adsorption capacity of phenol from cyclohexane onto polyacrylonitile was much less than that onto poly(p-nitrostyrene) or poly(p-vinylbenzyl amide). All these results revealed that adsorption of phenol from cyclohexane by poly(p-nitrostyrene) or poly(p-vinylbenzyl amide) is based on hydrogen-bonding.展开更多
Phase equilibria of hydrogen bonding （HB） fluid confined in a slit pore with broken symmetry were investigated by the density functional theory incorporated with modified fundamental measure theory, where the symmet...Phase equilibria of hydrogen bonding （HB） fluid confined in a slit pore with broken symmetry were investigated by the density functional theory incorporated with modified fundamental measure theory, where the symmetry breaking originated from the distinct interactions between fluid molecules and two walls of the slit pore. In terms of adsorption-desorption isotherms and the corresponding grand potentials, phase diagrams of HB fluid under various conditions are presented. Furthermore, through phase coexistences of laying transition and capillary condensation, the effects of HB interaction, pore width, fluid-pore interaction and the broken symmetry on the phase equilibrium properties are addressed. It is shown that these factors can give rise to apparent influences on the phase equilibria of confined HB fluid because of the competition between intermolecular interaction and fluid-pore interaction. Interestingly, a significant influence of broken symmetry of the slit pore is found, and thus the symmetry breaking can provide a new way to regulate the phase behavior of various confined fluids.展开更多
基金Supported by the National Natural Science Fsundation of China !(Grant No. 29574164)
文摘The adsorption isotherms of caffeine from aqueous solution onto three hydrogen donating adsorbents - hydroxypolystyrene. polystyrene-azo-pyrogallol, and D72 resin-were measured. The adsorption enthalpies calculated from the isotherms according to the Clausius-Clapeyron equation were-24~ -36kJ/mol, -32~ -37kJ/mol. and -19~ -24kJ/mol respectively These values implied that the absorption processes were based on hydrogen bonding. Furthermore, the mechanism of the adsorption of caffeine onto D72 resin was studied by IR spectra and the small molecular model experiments. and the results showed that the adsorption of caffeine onto hydrogen donating adsorbents was based on hydrogen bonding.
基金Supported by the National Natural Science Foundation of China! (Grant No. 29574164)
文摘A strongly hydrophilic hydrogen-bonding adsorbent-macroporous crosslinked poly(N- vinyl-acetamide). which contain both hydrogen bond acceptor and donator, was synthesized. Adsorption mechanism and dynamic adsorption of tannin from aqueous solution onto the adsorbent were investigated. Most of the differential adsorption heats for various adsorption capacities calculated from the adsorption isotherms according to Clapeyron-Clausius equation lay in the range of hydrogen bond energy (8-50kJ/mol). Adsorption properties of the adsorbent were studied in detail. These results revealed a hydrogen bonding mechanism of the adsorption of tannin from aqueous solution onto the adsorbent. The result of the dynamic adsorption of tanning with the initial concentration under 600 mg/L showed that the adsorption rate of tannin exceeded 90% when the flow rate was 3BV/h and the effluent volume reached 100 BV. Therefore, the developed hydrogen-bonding adsorbent--macroporous crosslinked poly(N-vinyl-acetamide)—is an excellent adsorbent to remove tannin from extract of natural products. and has great value in application.
文摘The interaction between a gas molecule and photocatalyst is vital to trigger photocatalytic reaction.The surface state of photocatalyst affects much in this interaction.Herein,adsorption of H2O molecules on s-triazine-based g-C3N4 was thoroughly studied by first-principle calculation.Although various initial adsorption models with multifarious locations of H2O molecules were built,the optimized models with strong adsorption energy pointed to the same adsorption configuration,in which the H2O molecule hold an upright orientation above the corrugated g-C3N4 monolayer.An intermolecular O-H…N hydrogen bond formed via the binding of a polar O-H bond in H2O molecule and a two-coordinated electron-rich nitrogen atom in g-C3N4.Under the bridging effect of this intermolecular hydrogen bond,electrons would transfer from g-C3N4 to the H2O molecule,thereby lowering the Fermi level and enlarging work function of g-C3N4.Interestingly,regardless of the substitute,i.e.g-C3N4 multilayer,large supercell and nanotube,this adsorption system was highly reproducible,as its geometry structure and electronic property remained unchanged.In addition,the effect of nonmetal element doping on adsorption energy was explored.This work not only disclosed a highly preferential H2O adsorbed g-C3N4 architecture established by intermolecular hydrogen bond,but also contributed to the deep understanding and optimized design in water-splitting process on g-C3N4-based photocatalysts.
基金Supported by the National Natural Science Foundation of China !(Grant No. 29574164 and 29974015)
文摘Two hydrogen-bonding adsorbents-macroporous crosslinked poly(p-nitrostyrene) and poly(p-vinylbenzyl amide)--were synthesized, and the absorption property of phenol from cyclohexane solution onto the adsorbents was studied. The differential adsorption heats for varied adsorption capacities calculated from the adsorption isotherms according to the Clapeyron-Clausius equation lay in the range of hydrogen bond energy (8-50kJ/mol). The adsorption capacity of o-nitrophenol in cyclohexane was much less than that of phenol under the same condition. The adsorption capacity of phenol from cyclohexane onto polyacrylonitile was much less than that onto poly(p-nitrostyrene) or poly(p-vinylbenzyl amide). All these results revealed that adsorption of phenol from cyclohexane by poly(p-nitrostyrene) or poly(p-vinylbenzyl amide) is based on hydrogen-bonding.
基金This work was supported by the National Natural Science Foundation of China （No.201374028 and No.21306034）, the Natural Science Foundation of Hebei Province （No.B2014201103）, and the Natural Science Foundation of Education Committee of Hebei Province （No.QN20131079）.
文摘Phase equilibria of hydrogen bonding （HB） fluid confined in a slit pore with broken symmetry were investigated by the density functional theory incorporated with modified fundamental measure theory, where the symmetry breaking originated from the distinct interactions between fluid molecules and two walls of the slit pore. In terms of adsorption-desorption isotherms and the corresponding grand potentials, phase diagrams of HB fluid under various conditions are presented. Furthermore, through phase coexistences of laying transition and capillary condensation, the effects of HB interaction, pore width, fluid-pore interaction and the broken symmetry on the phase equilibrium properties are addressed. It is shown that these factors can give rise to apparent influences on the phase equilibria of confined HB fluid because of the competition between intermolecular interaction and fluid-pore interaction. Interestingly, a significant influence of broken symmetry of the slit pore is found, and thus the symmetry breaking can provide a new way to regulate the phase behavior of various confined fluids.
