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Properties Governing the Transport of Trace Organic Contaminants through Ion-Exchange Membranes
journal contribution
posted on 2015-01-06, 00:00 authored by Marjolein Vanoppen, Annelise
F.A.M. Bakelants, Dorien Gaublomme, Klaas
V.K.M. Schoutteten, Julie Vanden Bussche, Lynn Vanhaecke, Arne R.D. VerliefdeIon exchange membranes could provide
a solution to the selective
separation of organic and inorganic components in industrial wastewater.
The phenomena governing the transport of organics through the IEM
however, are not yet fully understood. Therefore, the transport of
trace organic contaminants (TOrCs) as a model for a wide variety of
organic compounds was studied under different conditions. It was found
that in the absence of salt and external potential, the chemical equilibrium
is the main driver for TOrC-transport, resulting in the transport
of mainly charged TOrCs. When salt is present, the transport of TOrCs
is hampered in favor of the NaCl transport, which shows a preferential
interaction with the membranes due to its small size, high mobility
and concentration. It is hypothesized that electrostatic interactions
and electron donor/acceptor interactions are the main drivers for
TOrC transport and that transport is mainly diffusion driven. This
was confirmed in the experiments with different current densities,
where the external potential seemed to have only a minor influence
on the transport of TOrCs. It is only when the salt becomes nearly
completely depleted that the TOrCs are transported as charge carriers.
This shows that it is very difficult to get preferential transport
of organic compounds due to the diffusive nature of their transport.