The overall membrane pair characteristics included in the overall mass transport equation are understandable using the\r\nphenomenological equations expressed in the irreversible thermodynamics. In this investigation, the overall membrane pair\r\ncharacteristics (overall transport number ?, overall solute permeability �µ, overall electro-osmotic permeability f and overall\r\nhydraulic permeability ?) were measured by seawater electrodialysis changing current density, temperature and salt concentration,\r\nand it was found that �µ occasionally takes minus value. For understanding the above phenomenon, new concept of the overall\r\nconcentration reflection coefficient s* is introduced from the phenomenological equation. This is the aim of this investigation.\r\ns* is defined for describing the permselectivity between solutes and water molecules in the electrodialysis system just after an\r\nelectric current interruption. s* is expressed by the function of �µ and ?. s* is generally larger than 1 and �µ is positive, but\r\noccasionally s* becomes less than 1 and �µ becomes negative. Negative �µ means that ions are transferred with water molecules\r\n(solvent) from desalting cells toward concentrating cells just after an electric current interruption, indicating up-hill transport or\r\ncoupled transport between water molecules and solutes.
Loading....