Polyvinylidene Fluoride Membrane Via Vapour Induced Phase Separation for Oil/Water Emulsion Filtration

Abstract

Membrane-based technology is an attractive option for the treatment of oily wastewater because of its high oil removal efficiency, small footprint and operational simplicity. However, filtration performance is highly restricted by membrane fouling, especially when treating oil/water emulsion as a result of strong interaction between oil droplets and the hydrophobic property of the membrane. This study explores the fabrication of polyvinylidene fluoride (PVDF)-based membrane via the vapour induced phase separation (VIPS) method while incorporating polyvinyl pyrrolidone (PVP) as a hydrophilic additive to encounter membrane fouling issues and improve membrane filterability. The resulting membranes were characterized and tested for oil/water emulsion filtration to evaluate their hydraulic, rejection and anti-fouling properties. Results show that the changes in membrane morphology and structure from typical macrovoids with finger-like substructure to cellular structure and larger membrane pore size were observed by the prolonged exposure time from 0 to 30 min through the VIPS method. The enhanced clean water permeability is attributed to the addition of PVP–LiCl in the dope solution that enlarges the mean flow pore size from 0.210 ± 0.1 to 7.709 ± 3.5 µm. The best performing membrane was the VIPS membrane with an exposure time of 5 min (M-5), showing oil/water emulsion permeability of 187 Lm−2 h−1 bar−1 and oil rejection of 91.3% as well as an elevation of 84% of clean water permeability compared to pristine PVDF developed using a typical non-solvent induced phase separation (NIPS) method. Despite the relatively high total fouling, M-5 was able to maintain its high permeability by water flushing as a simple operation for membrane fouling control. The performance was achieved thanks to combination of the large mean flow pore size and hydrophilic property from residual PVP in the membarne matrix. Overall, the results demonstrate the potential of the optimum VIPS method in the presence of PVP and LiCl additives for oil/water emulsion treatment.

Cigarette Butt Waste as Material for Phase Inverted Membrane Fabrication Used for Oil/Water Emulsion Separation

“…As expected, the total fouling for all three types of membranes showed an increasing trend with the increasing filtration cycles. The trend of multiple cycle performance is consistent with our earlier report treating the same feed following similar filtration cycles [10][11][12]47]. The three membranes pose quite distinct fouling reversibility.…”

“…Conventional methods (flotation and coagulation) for the treatment of stable oil/water emulsions are less effective in handling micron-sized emulsion droplets and finely dispersed oil particles [9]. The membrane-based process is seen as one of the emerging methods for treating oil/water emulsion wastewater that has been shown effective in handling low concentration of oil (<1000 ppm) in water [10][11][12]. It outstands the conventional separation techniques for simplicity, continuous, faster, and cost-effectiveness due to their low energy consumption.…”

Development of Polyvinylidene Fluoride Membrane via Assembly of Tannic Acid and Polyvinylpyrrolidone for Filtration of Oil/Water Emulsion

“…Oil droplets in oil/water emulsion easily foul plain PVDF membrane since oil droplets can strongly adhere to the membrane surface [10]. Fortunately, PVDF-based membrane can be made hydrophilic by incorporating additives during membrane fabrication to overcome its high membrane fouling propensity [11,12]. For instance, Cui et al [4] reported a biomimetic surface modification by virtue of the polydopamine anchored by silicone dioxide on the PVDF membrane by enzymatic oxidation.…”

Fabrication of Polyvinylidene Difluoride Membrane with Enhanced Pore and Filtration Properties by Using Tannic Acid as an Additive

“…Slight increments of the water fluxes were observed in all cases but were statistically insignificant. Judging from the high stability of PVDF, a small change in flux can be attributed to the degradation of residual TA that left the void and turned the membrane structure to be more porous and/or the membrane pore to be larger, as also occurred when employing a dragon blood in resin [ 6 ], PEG [ 38 ] or PVP as additive [ 39 ]. However, the water flux increment for the pristine PVDF membranes suggests that the treatment might also affect the PVDF polymer.…”