Table 1: Some characteristics of commercial MK-40, MA-40, and surface-modified MK-40/Nf and MA-40M membranes.

MembranesCation exchangeAnion exchange
MK-40MK-40/NfMA-40MA-40M

Ion exchange groups, bulk =NH, N=NH, N
Idem, surface =NH, N
Thickness, μm
Ion exchange capacity1, mM cm−3 wet
Surface fraction of ion exchange material2, % 100
Contact angle3, degrees
Specific electrical conductivity in 0.5 M NaCl solution4, mS cm−1
Diffusion permeability5, 10−8 cm2 s−1

1Ion exchange capacity was determined for wet membranes in the sodium form (cation exchange membranes) or in the chloride form (anion exchange membranes).
2Surface fraction of ion exchange material was determined for a wet membrane using SEM images by the method described in [21].
3Contact angle on the surface of wet membrane was found 20 s after placing a test drop, according to the method described in [18].
4Specific electrical conductivity of membrane in 0.5 M NaCl solution was determined by a difference method using a clip cell [28].
5Diffusion permeability of membranes was determined in H2O/IEM/0.5 M NaCl system using the cell described in [29]; the modified side of MK-40/Nf membrane was facing the NaCl solution; the left- and right-hand sides of MK-40, MA-40, and MA-40M membranes are symmetrical.