Fabrication and Evaluation of Polyethersulfone/Sulfonated-Polyethersulfone Blend Membranes for Treatment of Oil-Containing Wastewaters

Research subject: Oil-based wastewater treatment is essential to prevent environmental harm and comply with regulations. Membrane processes are ideal for this due to their efficiency, low energy use, and ability to handle complex emulsions effectively.
Research approach: The primary goal of this study is to employ ultrafiltration membrane separation process for treatment of wastewater containing oil compounds (e.g., diesel fuel). To achieve this, polyethersulfone/sulfonated polyethersulfone (PES/SPES) blend membranes were fabricated using nonsolvent-induced phase separation (NIPS) method. The effects of SPES loading on the membrane morphology, surface roughness, hydrophilicity, mechanical strength, porosity, and water and wastewater flux were investigated through scanning electron microscopy (SEM), atomic force microscopy (AFM), water contact angle measurement, mechanical strength testing, and filtration performance tests, respectively.
Main results: The results showed that adding SPES to PES led to the formation of macrovoids in the membrane cross-section, higher surface roughness, enhanced hydrophilicity, increased porosity, improved water and wastewater flux, and higher flux recovery. However, these benefits came with reduced mechanical strength and increased membrane compaction. Among the prepared membranes, the PES/SPES (40/60) blend membrane exhibited the best filtration performance, achieving a final wastewater flux of 34.78 L/m².h, compared to 11.35 L/m².h for the neat PES membrane. Meanwhile, the PES/SPES (60/40) composite demonstrated the highest surface roughness, hydrophilicity, and flux recovery ratio. Notably, all membranes synthesized in this study achieved over 99% rejection efficiency for the oil-water emulsions, which is significant for practical and industrial applications.