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Cake layer: Layer comprised of rejected particulate materials residing on the upstream face of a membrane.
Capillary membrane: A version of hollow fiber membrane with outer diameter of 0,5 - 5 mm.
Carrier complexation coefficient, Kc, [kmol m-3]: Parameter defined as the ratio of the rate constants for the second order complexation and first order decomplexation reaction between a carrier and a penetrant: viz., A + M = AM [Note: Kc = kc/kd, where A & M, resp., are a penetrant and a carrier site within a membrane].
Carrier complexation: Phenomenon in which carrier molecules form a coordinated structure with penetrant molecules.
Carrier deactivation: Chemical transformations involving a carrier entity which render it less capable of undergoing the desired interaction with a penetrant
Carrier leaching: Loss of carrier due to its partitioning by mass transport into one or both external phases.
Carrier-mediated (facilitated) transport): Process in which chemically distinct carrier species form complexes with a specific component in the feedstream, thereby increasing the flux of this component relative to other components.
Catalytic membrane: Membrane with catalytic properties or a porous support with coated catalyst.
Cation-exchange membrane: Membrane containing fixed anionic charges and mobile cations which can be exchanged with other cations present in an external fluid in contact with the membrane.
Ceramic membrane: Membrane manufactured from ceramic materials.
Charge-mosaic membrane: Synthetic membrane composed of two-dimensional or three-dimensional alternating cation- and anion-exchange channels throughout the membrane.
Charged membrane: Membrane that contains functional groups capable to ionization.
Circulation regime: A variant of flow regime with full or partial return of the retentate or permeate streams into the inlet of membrane apparatus.
Co-current flow: Flow pattern through a membrane module in which the fluids on the upstream and the downstream sides of the membrane move parallel to the membrane surface and in the same directions.
Co-ions: The ions with the same charge as fixed ions formed via dissociation of functional groups in ion-exchange membranes.
Coefficient of volume reduction: The ratio of volume flux (or volume) of the feed to that of concentrate.
Completely-mixed (perfectly-mixed) flow: Flow through a membrane module in which fluids on both the upstream and downstream sides of the membrane are individually well-mixed.
Complexation rate constant, ka [kmol-1 m3 s-1]: Carrier complexation rate divided by the product of the local concentrations of the carrier and the complexable component, viz., kc = (complexation rate)/ [(c)carrier(c)complexable component] where concentrations are given in [kmol m-3] and complexation rate is given in [kmol m-3 s-1].
Composite membrane: Membrane having chemically or structurally distinct layers
Concentrate: A liquid stream or volume that has not passed through membrane in a baromembrane process.
Concentration chamber: Membrane channel of multi-chamber apparatus for electrodialysis; it is limited by two membranes (cation- and anion-exchanged membranes); into this chamber the ion from neighboring chambers are transferred.
Concentration coefficient: Ratio of the concentration of a compound in the concentrate to that in the separated mixture.
Concentration factor: Ratio of the concentration of a component i in the retentate to the concentration of the same component in the feed.
Concentration polarization: Concentration profile that has a higher level of solute nearest to the upstream membrane surface compared with the more-or-less well- mixed bulk fluid far from the membrane surface.
Continuous membrane column: Membrane module(s) arranged in a manner to allow operation analogous to that of a distillation column, with each module acting as a stage (see Membrane cascade).
Counter-current flow: Flow through a membrane module in which the fluids on the upstream and downstream sides of the membrane move parallel to the membrane surface but in opposite directions
Counterion: The dominating type of mobile ions in ion-exchange membrane that are formed by dissociation of its functional groups.
Coupled transport: Process in which the flux of one component between the upstream and downstream is linked to the flux of a second component.
Cross flow: Flow through a membrane module in which the fluid on the upstream side of the membrane moves parallel to the membrane surface and the fluid on the downstream side of the membrane moves away from the membrane in the direction normal to the membrane surface.
