A new equation for predicting surface tension is proposed based on the thermodynamic definition of surface tension and the expression of the Gibbs free energy of the system. Using the NRTL equation to represent the ex...A new equation for predicting surface tension is proposed based on the thermodynamic definition of surface tension and the expression of the Gibbs free energy of the system. Using the NRTL equation to represent the excess Gibbs free energy, a two-parameter surface tension equation is derived. The feasibility of the new equation has been tested in terms of 124 binary and 16 multicomponent systems(13-ternary and 3-quaternary) with absolute relative deviations of 0.59% and 1.55% respectively. This model is also predictive for the temperature dependence of surface tension of liquid mixtures. It is shown that, with good accuracy, this equation is simple and reliable for practical use.展开更多
The streaming potential of poly（vinyl butyral） （PVB） hollow fiber membrane was studied in different electrolyte solutions （including NaCl, KCl, CaCl2 and MgCl2）, the effects of ionic strength, ion valence and pH...The streaming potential of poly（vinyl butyral） （PVB） hollow fiber membrane was studied in different electrolyte solutions （including NaCl, KCl, CaCl2 and MgCl2）, the effects of ionic strength, ion valence and pH value on the streaming potential （SP） of the membrane were investigated. The zeta potentials and surface charge densities of the membrane were estimated on the basis of Helmholtz-Smoluchowski equation and Gouy-Chapmann theory. The results show that the PVB membrane has a weak negative charge due to the specific adsorption of ions. Moreover, the streaming potential, the zeta potential and the surface charge density of the membrane depend strongly on the salt concentration and the type and valence of ions. The iso-electric point （IEP） of the PVB membrane is arotmd 3.0 in the monovalent media （NaC1 and KC1） and 3.5 in divalent electrolytes （CaCl2 and MgCl2）. A few retentions were obtained for PVB membrane in low concentration solutions. This result verifies that the negative charged membrane surface can reject inorganic solutes by means of electrostatic repulsion effect even though the size of membrane pores is much larger than the size of salts.展开更多
The flow of a freely falling liquid film of low Reynolds number down a vertical long periodic sine-shaped wavy plate of small corrugations is researched theoretically. A model based on perturbation method and power se...The flow of a freely falling liquid film of low Reynolds number down a vertical long periodic sine-shaped wavy plate of small corrugations is researched theoretically. A model based on perturbation method and power series is presented. A stream function is introduced into the governing equations and two sets of equations describing the film flow separately at zeroth and first order are developed. The zeroth order equation is solved directly. The first order equations is solved at the leading approximation. Effect of parameters Re, M, λ and ε on the free surface wave of film is discussed.展开更多
基金the Scientific Research Foundation of the State Education Ministry for Returned Overseas Chinese Scholar.
文摘A new equation for predicting surface tension is proposed based on the thermodynamic definition of surface tension and the expression of the Gibbs free energy of the system. Using the NRTL equation to represent the excess Gibbs free energy, a two-parameter surface tension equation is derived. The feasibility of the new equation has been tested in terms of 124 binary and 16 multicomponent systems(13-ternary and 3-quaternary) with absolute relative deviations of 0.59% and 1.55% respectively. This model is also predictive for the temperature dependence of surface tension of liquid mixtures. It is shown that, with good accuracy, this equation is simple and reliable for practical use.
基金Project(21176264)supported by the National Natural Science Foundation of ChinaProject(11JJ2010)supported by the Hunan Provincial Natural Science Foundation of China+1 种基金Project(CL11096)supported by the Undergraduate Innovation Training Foundation of Central South University,ChinaProject(BL12053)supported by the Undergraduate Innovation Training Foundation of Hunan Province,China
文摘The streaming potential of poly（vinyl butyral） （PVB） hollow fiber membrane was studied in different electrolyte solutions （including NaCl, KCl, CaCl2 and MgCl2）, the effects of ionic strength, ion valence and pH value on the streaming potential （SP） of the membrane were investigated. The zeta potentials and surface charge densities of the membrane were estimated on the basis of Helmholtz-Smoluchowski equation and Gouy-Chapmann theory. The results show that the PVB membrane has a weak negative charge due to the specific adsorption of ions. Moreover, the streaming potential, the zeta potential and the surface charge density of the membrane depend strongly on the salt concentration and the type and valence of ions. The iso-electric point （IEP） of the PVB membrane is arotmd 3.0 in the monovalent media （NaC1 and KC1） and 3.5 in divalent electrolytes （CaCl2 and MgCl2）. A few retentions were obtained for PVB membrane in low concentration solutions. This result verifies that the negative charged membrane surface can reject inorganic solutes by means of electrostatic repulsion effect even though the size of membrane pores is much larger than the size of salts.
基金Acknowledgement： This work is supported by Natural Science Foundation of Tianjin of China （No. 07JCYBJC01300）.
文摘The flow of a freely falling liquid film of low Reynolds number down a vertical long periodic sine-shaped wavy plate of small corrugations is researched theoretically. A model based on perturbation method and power series is presented. A stream function is introduced into the governing equations and two sets of equations describing the film flow separately at zeroth and first order are developed. The zeroth order equation is solved directly. The first order equations is solved at the leading approximation. Effect of parameters Re, M, λ and ε on the free surface wave of film is discussed.
