posted on 2021-04-29, 08:46authored byDennis
Maik Reurink, Wiebe M. de Vos, Hendrik D. W. Roesink, Joris de Grooth
Polyelectrolyte multilayers
(PEMs) are highly promising materials
as selective separation layers on the inside of hollow fiber membranes.
We investigate the forward osmosis (FO) performance of poly(4-styrene
sulfonate) (PSS)/poly(allylamine) (PAH)- and PSS/poly(ethylene imine)-based
PEM membranes and apply different draw solutions. The PEM membranes
show different separation properties, demonstrated by their retention
behavior under nanofiltration conditions against five relevant draw
solutions (NaCl, MgCl2, MgSO4, Na2SO4, and trisodium citrate (TSC)). Subsequently, the relation
between PEM properties and FO performance was studied for various
draw solutions. PSS/PAH membranes showed the lowest reverse salt flux
for MgCl2 and MgSO4, while the PSS/PEI membranes
showed the lowest reverse salt flux for Na2SO4 and TSC. Combining the right PEM membrane with the right draw solution
is thus key to getting low reverse salt fluxes in FO. Cross-linking
of the PEMs resulted in an overall lower salt and water flux; however,
the reverse salt flux selectivity was not affected.