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.
Highlights
IntroductionImproper discharge of wastewater leads to environmental and ecological pollution
Improper discharge of wastewater leads to environmental and ecological pollution.It is promoted by massive industrial activities including oil and oleochemicals
The results demonstrate a clear relationship between the exposure time with the morphology of resulting polyvinylidene fluoride (PVDF)
Summary
Improper discharge of wastewater leads to environmental and ecological pollution. It is promoted by massive industrial activities including oil and oleochemicals. Rapid industrial development in the oil and gas, petrochemical, pharmaceutical and food industries have led to large production of oily wastewater [1]. Production of the palm oil mill effluent (POME) is one of main industrial causes of the production of oily wastewater in Southeast Asian countries such as Indonesia, Malaysia and Thailand, which produced approximately 36, 21 and 2 million × 103 kg of palm oil, respectively, in. It is crucial to properly treat the wastewater that contains oil/water emulsion to lower the oil content for either reuse or discharge purposes
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