1 research outputs found
Short- and Long-Term Performance of the Thin-Film Composite Forward Osmosis (TFC-FO) Hollow Fiber Membranes for Oily Wastewater Purification
Fouling behavior of thin-film composite
(TFC) membranes synthesized
on sulfonated polyphenylenesulfone (sPPSU) hollow fiber substrates
was investigated for separating oil–water emulsions under forward
osmosis (FO). The water and salt reverse fluxes of the TFC-FO hollow
fiber membranes were found to be stable for a period of 28 days when
deionized (DI) water was used as feed. A series of fouling experiments
were carried out, and it was observed that water flux decreased faster
with increasing oil concentration of the feed solution. In addition,
the rate of flux decline was rapid in the initial few hours, because
of the cake-enhanced concentration polarization (CECP). Furthermore,
we observed that the ratio of salt reverse flux to water flux (<i>J</i><sub>s</sub>/<i>J</i><sub>w</sub>) was much lower,
compared to that of using DI water as feed. This may indicate that
the oil fouling plugs some defects in the selective layer and the
oil fouling layer hinders the salt transport, because of the CECP
mechanism. Further investigations revealed that the FO fouling could
be efficiently washed off using a solution containing 1 g/L NaOH and
0.3 g/L sodium dodecyl sulfate (SDS), and the water flux could be
effectively recovered, to a large extent, within 5 days when separating
a 500 ppm oil–water emulsion. Overall, the newly developed
FO membranes can recover ∼80% of the water at a high average
water flux of 10.4 LMH using 1 M NaCl as draw solution from a 500
ppm oil–water emulsion containing a low salt concentration
of 0.5 g/L. This, in turn, demonstrates the potential of the FO membranes
for oily wastewater reclamation