The salt effects on molecular orientation at air/liquid methanol interface were investigated by the polarization-dependent sum frequency generation vibrational spectroscopy（SFG-VS）. We clarified that the average til...The salt effects on molecular orientation at air/liquid methanol interface were investigated by the polarization-dependent sum frequency generation vibrational spectroscopy（SFG-VS）. We clarified that the average tilting angle of the methyl group to be u = 308 58 at the air/pure methanol surface assuming a d-function orientational distribution. Upon the addition of 3 mol/L Na I, the methyl group tilts further away from the surface normal with a new u = 418 38. This orientational change does not explain the enhancement of the SFG-VS intensities when adding Na I, implying the number density of the methanol molecules with a net polar ordering in the surface region also changed with the Na I concentrations. These spectroscopic findings shed new light on the salt effects on the surfaces structures of the polar organic solutions. It was also shown that the accurate determination of the bulk refractive indices and Raman depolarization ratios for different salt concentrations is crucial to quantitatively interpret the SFG-VS data.展开更多
Molecular dynamics（MD） simulation was performed to investigate the influence of external electric field on the vapottr-liquid interface of the bubble during the process of toluene separation by air flotation. The ph...Molecular dynamics（MD） simulation was performed to investigate the influence of external electric field on the vapottr-liquid interface of the bubble during the process of toluene separation by air flotation. The physico- chemical properties of vapour-liquid interface, surface tension, probability of a hydrogen bonding near the vapour- liquid interface and the viscosity of liquid phase caused by external electric field were analyzed. The results show that the angle between the water molecule dipole moment and the normal z axis in the vapour phase changes smaller when the external electric field is applied. The surface tension and the probability of hydrogen bonding near the vapour-liquid interface increase with the increase of electric field strength. And the viscosity also increases tinder an external electric field. The results confirm that the external electric field has a positive effect on the performance of bubbles in air flotation, which may provide useful guidance for the combination of electric field and air flotation technology.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 21227802, 21303216 and 21473217)
文摘The salt effects on molecular orientation at air/liquid methanol interface were investigated by the polarization-dependent sum frequency generation vibrational spectroscopy（SFG-VS）. We clarified that the average tilting angle of the methyl group to be u = 308 58 at the air/pure methanol surface assuming a d-function orientational distribution. Upon the addition of 3 mol/L Na I, the methyl group tilts further away from the surface normal with a new u = 418 38. This orientational change does not explain the enhancement of the SFG-VS intensities when adding Na I, implying the number density of the methanol molecules with a net polar ordering in the surface region also changed with the Na I concentrations. These spectroscopic findings shed new light on the salt effects on the surfaces structures of the polar organic solutions. It was also shown that the accurate determination of the bulk refractive indices and Raman depolarization ratios for different salt concentrations is crucial to quantitatively interpret the SFG-VS data.
基金Supported by the National Natural Science Foundation of China（No. 51408525）.
文摘Molecular dynamics（MD） simulation was performed to investigate the influence of external electric field on the vapottr-liquid interface of the bubble during the process of toluene separation by air flotation. The physico- chemical properties of vapour-liquid interface, surface tension, probability of a hydrogen bonding near the vapour- liquid interface and the viscosity of liquid phase caused by external electric field were analyzed. The results show that the angle between the water molecule dipole moment and the normal z axis in the vapour phase changes smaller when the external electric field is applied. The surface tension and the probability of hydrogen bonding near the vapour-liquid interface increase with the increase of electric field strength. And the viscosity also increases tinder an external electric field. The results confirm that the external electric field has a positive effect on the performance of bubbles in air flotation, which may provide useful guidance for the combination of electric field and air flotation technology.
基金supported by the National Natural Science Foundation of China(20903078)China Postdoctoral Science Foundation(2011M500540)+1 种基金Scientific Research Foundation for Returned Overseas Chinese Scholars of Hebei Province,China(2011052)Support Program for Hundred Excellent Innovation Talents from Universities and Colleges of Hebei Province,China(CPRC020)~~
