a

Active layer: see Selective layer.

Anchored (bound) carrier: Distinct species bonded chemically to fixed sites_, within a membrane for the purpose of increasing the selective sorption and flux of a specific component in a feed stream relative to all other components.

Anion-exchange membrane: Membrane containing fixed cationic charges and mobile anions that can be exchanged with other anions present in an external fluid in contact with the membrane.

Anisotropic membrane: Membrane that has non-uniform structure or composition along the cross-section.

Anisotropy of membranes: Non-uniform cross-section character of membrane material. For example, for porous membranes anisotropy can be revealed in differences in pore size in the selective layer and support.

Asymmetric membrane: Membrane that includes two or more layers of non-identical morphologies (see also Anisotropic membrane).

Asymmetry of membranes: see Anisotropy of membranes