Pvdf-tio2 nanocomposite membrane with anti-fouling properties for oil emulsion removal
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Date
2016-09-01
Authors
Susan Ling Ying
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Abstract
Polyvinylidene fluoride (PVDF) membrane is prone to be fouled by oil
emulsions which could not be easily cleaned via surface washing. Besides, hydrophilic
nature of titanium dioxide (TiO2) changes the thermodynamic stability of the polymer
solution during phase inversion and caused membrane with altered morphology. In
this study, PVDF–TiO2 mixed-matrix membranes with UV-cleaning properties were
synthesized for crude oil emulsion removal at high salinity condition. The effect of
membrane synthesis parameter, namely polymer concentrations, type of
solvents, TiO2 type and concentrations, and polyethylene glycol (PEG)
concentrations were investigated. The physicochemical properties of the membrane
were characterized and related to its performance and antifouling
properties. Membrane pore size and porosity were the dominating effects of
membrane fouling by oil emulsions. In term of antifouling, the optimum membrane
synthesis parameter was obtained by 18 wt.% PVDF with N, Ndimethylacetamide
(DMAc) as solvent added with 3 wt.% of P25 TiO2. The
obtained pure water permeation flux was 160.19 ± 11.54 L/m2.hr, rejection of 96.27 ±
0.28 % with flux recovery ratio (FRR) of 23.40 ± 1.10 %. It was found that the critical
pressure to avoid irreversible fouling should be lower than 1.5 bar whereby cake layer
resistance is the main fouling mechanism. Upon 30 min of UV irradiation, the mixedmatrix
membrane exhibited drastic FRR improvement of 90.42 ± 4.90 %, which
confirms the photocatalytic property of TiO2 nanoparticles in degrading the adsorbed
oil emulsions on the membrane surface. Nonetheless, further increased of UV
irradiation duration and intensity could deteriorate the membrane performance due to
pore blockage caused by the oil fragmentation and pore enlargement.