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BACKGROUND In this work, a series of graphene oxide–polyethersulfone (GO–PES) composite flat sheet (FS) and hollow fiber (HF) membranes were fabricated by blending 0.5 and 1.0 wt% of GO into the PES matrix and utilized for oil–water separation. GO was first prepared and characterized by using Fourier‐transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X‐ray diffraction (XRD) and thermogravimetric analysis (TGA) before being used as membrane fillers. RESULTS Interestingly, although similar dope composition was used for the fabrication of HF and FS membranes, their morphology and pore size varied significantly owing to the way the membranes were fabricated. Significant enhancement of hydrophilicity was observed for both composite FS and HF membranes, where the water contact angle value decreased from 74.8° to 42.2° and 71.4° to 49.8°, respectively. The flux of the composite membranes increased up to 150% of the bare membranes especially when 1.0 wt% of GO was added. Although higher oil rejection (~99%) was observed for HF membranes that possess smaller pores, the permeation flux was maintained due to the improved flow dynamic. Lower oil rejection (up to 50%) was observed for FS membranes, which might be due to its big pore sizes particularly at the bottom surface. As more oil droplets formed on the membrane surface and prevented water molecules to pass through the membrane, fouling might occur rapidly. CONCLUSIONS The results obtained in this work suggest that surface hydrophilicity, pore size of membranes and oil–water separation performances was greatly affected by membrane shape. Owing to many advantages of HF membranes, this type of membrane has great potential for commercial applications. © 2020 Society of Chemical Industry

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Membrane based separation system is considered as a promising technology to purify water, owing to its simplicity and efficiency in operation. However, the application is limited by membrane fouling, which can lead to the declination of water flux and premature failure of membrane. The fouling can be controlled through membrane surface modification by blending hydrophilic materials during the casting solution preparation. Polyethersulfone (PES) membrane is naturally hydrophobic due to lack of oxygen functional group, which limits its application in the filtration of water. Therefore, modification of PES-based membranes is required. In this work, modification of the PES membrane was carried out by incorporating carbon-based nanomaterials (graphene oxide (GO)) and a well-known organic polymer (polyvinylpyrrolidone (PVP)). The effect of each additive toward the hydrophilicity of composite PES membrane was then investigated. GO was synthesized using modified Hummers method due to its simpler and shorter process. Each additive was added during the casting solution preparation and the amount added was varied from 0.5 to 1.0 wt%. The resultant composite PES membranes were characterized using XRD, FTIR and TGA prior to hydrophilicity and pure water flux (PWF) measurement. It was observed that the additives (PVP and GO) have significantly affected the membranes hydrophilicity, resulting in lower contact angle and higher pure water flux. The highest value of PWF (230 L/m2.h) with lowest contact angle (42 °) were observed for PES-1.0GOPVP membrane due to high amount of GO and PVP. Improved PWF performance of composite PES-1.0GOPVP membrane was attributed to the better dispersibility of the PVP and GO and increased surface hydrophilicity of the modified composite membranes. This study indicated that PVP and GO are effective modifiers to enhance the performance of PES membrane

Polyethersulfone/Titanium oxide (PES/TiO2) composite membranes at various compositions of TiO2 nanoparticle (0, 0.1 and 0.5 wt. %) were prepared via phase inversion method. The prepared composite membranes were then tested for degradation process and separation process for oily wastewater. It was found that the addition of TiO2 that possess visible-light response activity led to an improvement of the membrane performances especially in photocatalytic activities. The membrane performances were also investigated by using liquid separation system in order to obtain the flux/permeation rate and also the percentage of oil removal by the membranes. The results indicate that the increment the amount of TiO2 nanoparticle in the composite membrane reduced the permeation flux. Further study has been made by characterizing the membranes in terms of contact angle, Field Emission Scanning Electron Microscope (FESEM), Fourier Transform Infrared Spectrometer (FTIR) and X-Ray Diffraction (XRD) analysis. The characterization results indicate that the TiO2 nanoparticles were uniformly mixed in the membrane. The increased of membrane hydrophilicity was demonstrated by the contact angle measurement. By adding TiO2, the membrane hydrophilicity was observed to be better than the neat PES composite membrane. Cross sectional images from FESEM also indicate that the addition of TiO2 nanoparticles help in increasing the macro-void of the membranes. Finally, a comparison between neat PES membrane and PES/TiO2 nanoparticle membrane proved that addition of TiO2 nanoparticle can be one of the ways to maximize the removal of oil.