CHAPTER 12: Oil–Water Separation with Selective Wettability Membranes

Every day millions of gallons of oil–water mixtures are produced in industries ranging from oil extraction, fracking and mining, to wastewater treatment. Separating these mixtures involves multiple unit operations, which can be expensive and sometimes insufficient, especially as environmental restrictions become increasingly strict on contaminants in discharged water. Other occurrences, such as large oil spills, also require new technologies that enable effective yet economic clean-up. Energy efficient, selective wettability-based membrane technology has the potential to meet these needs. In this chapter, we discuss the fundamentals of wettability and how they can be applied to systematically design membranes with selective wettability that can readily separate free oil and water, as well as emulsions. We also look at membrane surface morphology, surface energy, and the relationships that govern the selective breakthrough of an oil or water phase. Finally, we discuss the recent work in developing oil–water separation membranes based on the idea of selective wettability, the merits and shortcomings of each approach, and the potential areas of future interest in the field.