Durable Hydrophilic PVDF Hollow Fiber Membrane for Dissolved Organics Separation from High-Salinity Produced Water

Organic compounds are major constituents in produced water that have gained increasing attention due to their negative impacts on operations and the environment. In this study, a novel hydrophilic polyvinylidene fluoride (PVDF) hollow fiber (HF) membrane was formulated and fabricated for organics separation (OS) from oilfield-produced water. The PVDF dope solution was formulated with lithium chloride (LiCl) and polyvinylpyrrolidone (PVP) as synergistic pore agents, and the obtained PVDF HF membranes showed a defect-free asymmetric structure with a stable hydrophilicity. The OS performance was studied in terms of permeate water flux, OS efficiency, and long-term membrane stability using both decanoic acid and real produced water as feed solutions. Specifically, the effects of operating parameters, such as pressure, total organic carbon (TOC), pH, and salinity, on the OS performance were examined in decanoic acid solution. The long-term membrane stability was evaluated through a 60 h continuous OS experiment using real produced water as the feed solution. The used membrane was thoroughly characterized to understand both scaling and fouling phenomena during the OS operation. The results indicated that the membranes showed promising permeate water flux (>500 kg/m2/h at 350 kPa) and OS efficiency (>92%). It also exhibited a near-100% recovery of organics separation efficiency during six cyclic OS experiments due to consistent membrane hydrophilicity.