Expanded Polytetrafluoroethylene/Graphite Composites for Easy Water/Oil Separation

Abstract

Oil spills in the ocean greatly threaten local environments, marine creatures, and coastal econo¬mies. A automatic water/oil separation material system was proposed in this study and a tubular geometry was chosen to demonstrate the water/oil separation efficiency and effectiveness. The water/oil separation tubes were made of expanded polytetrafluoroethylene (ePTFE) and gra¬phite composites. The permeation pressures of water and oil through the tube walls were tuned by adjusting the ePTFE microstructure, which in turn, depended on the degree of expansion and the graphite content. Fourier-transform infrared spectroscopy was performed to confirm the com¬positions of the ePTFE/graphite com¬po¬sites and scanning electron microscope was used to examine the microstructure and morphology of the expanded PTFE/graphite composite tubes. When a proper pressure was applied, which was higher than the oil’s permeation pressure (3.0 kPa) but lower than the water’s permeation pressure (57 kPa), the oil leaked out of the tube walls while the water went through the ePTFE/graphite tubes. As such, the water/oil mixture could be separated and collected in different containers or an outer tube. Due to this automatic separation, the whole process could be done continuously and conveniently, thus exhibiting great potential in the practical application of oil spill and water separation/remediation.