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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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.
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