d
Damkohler number: Dimensionless number equal to the characteristic time l2/DAM) for diffusion of complexed component across a membrane of thickness, l, divided by the characteristic time (kd-1) for the decomplexation reaction between a carrier (M) and a complexed penetrant, A, viz., l2/(DAMkd) when DAM is the effective diffusion coefficient of the complexed carrier entity in the membrane.
Dead-end flow: Flow through a membrane module in which the only outlet for upstream fluid is through the membrane.
Decomplexation rate constant, kd, [s-1]: Ratio of the decomplexation rate to the product of the local concentration of the complexed carrier, viz., kd = (decomplexation rate) / (c)compiexed carrier {Note: typical units for decomplexation rate are [kmol m-3 s-1], and for complexed carrier are [kmol m-3]}.
Dense (non-porous) membrane: Membrane with no detectable pores.
Diafiltration: A variant of baromembrane process for separation of dissolved high-molecular-mass and low-molecular-mass compounds; in this process the concentrate is diluted with the solvent so better separation is achieved.
Dialysate: A mixture of compounds that penetrate through a membrane in the process of dialysis.
Dialysator: Membrane apparatus for performing dialysis.
Dialysis permeability coefficient: Permeability coefficient based on a transmembrane driving force expressed in terms of the concentration difference of a given component.
Dialysis: Membrane process in which transport is driven primarily by concentration differences, rather than by pressure or electrical-potential differences, across the thickness of a membrane
Donnan exclusion: Reduction in concentration of mobile ions within an ion exchange membrane due to the presence of fixed ions of the same sign as the mobile ions.
Downstream: Side of a membrane from which permeate emerges.
Drainage: A part of a membrane element located directly below the membrane; it provides a mechanical support for the membrane and allows an efficient removal of permeate.
Driving force: Gradient of chemical or electric potential across the membrane that induces mass transfer through the membrane.
Driving force: The gradient of chemical or electric potential across the membrane which is the reason for mass transfer through the membrane.
Dry-phase separation membrane formation: Process in which a dissolved polymer is precipitated by evaporation of a sufficient amount of solvent to form a membrane structure (Note: Appropriate mixtures of additives are present in solution with the polymer to alter its precipitation tendency during solvent evaporation).
Dry-wet phase separation membrane formation: Combination of the dry- and the wet-phase formation processes.
Dynamic membrane formation: Process in which an active layer is formed on the membrane surface by the deposition of substances contained in the fluid being treated.
Damkohler number: Dimensionless number equal to the characteristic time l2/DAM) for diffusion of complexed component across a membrane of thickness, l, divided by the characteristic time (kd-1) for the decomplexation reaction between a carrier (M) and a complexed penetrant, A, viz., l2/(DAMkd) when DAM is the effective diffusion coefficient of the complexed carrier entity in the membrane.
Dead-end flow: Flow through a membrane module in which the only outlet for upstream fluid is through the membrane.
Decomplexation rate constant, kd, [s-1]: Ratio of the decomplexation rate to the product of the local concentration of the complexed carrier, viz., kd = (decomplexation rate) / (c)compiexed carrier {Note: typical units for decomplexation rate are [kmol m-3 s-1], and for complexed carrier are [kmol m-3]}.
Dense (non-porous) membrane: Membrane with no detectable pores.
Diafiltration: A variant of baromembrane process for separation of dissolved high-molecular-mass and low-molecular-mass compounds; in this process the concentrate is diluted with the solvent so better separation is achieved.
Dialysate: A mixture of compounds that penetrate through a membrane in the process of dialysis.
Dialysator: Membrane apparatus for performing dialysis.
Dialysis permeability coefficient: Permeability coefficient based on a transmembrane driving force expressed in terms of the concentration difference of a given component.
Dialysis: Membrane process in which transport is driven primarily by concentration differences, rather than by pressure or electrical-potential differences, across the thickness of a membrane
Donnan exclusion: Reduction in concentration of mobile ions within an ion exchange membrane due to the presence of fixed ions of the same sign as the mobile ions.
Downstream: Side of a membrane from which permeate emerges.
Drainage: A part of a membrane element located directly below the membrane; it provides a mechanical support for the membrane and allows an efficient removal of permeate.
Driving force: Gradient of chemical or electric potential across the membrane that induces mass transfer through the membrane.
Driving force: The gradient of chemical or electric potential across the membrane which is the reason for mass transfer through the membrane.
Dry-phase separation membrane formation: Process in which a dissolved polymer is precipitated by evaporation of a sufficient amount of solvent to form a membrane structure (Note: Appropriate mixtures of additives are present in solution with the polymer to alter its precipitation tendency during solvent evaporation).
Dry-wet phase separation membrane formation: Combination of the dry- and the wet-phase formation processes.
Dynamic membrane formation: Process in which an active layer is formed on the membrane surface by the deposition of substances contained in the fluid being treated.
