Polyethersulfone/Cellulose Acetate Butyrate Hybrid Hollow-Fiber Membranes for Organic-Matter Removal From Produced Water

Abstract

Summary In the US, for every barrel of oil, approximately 7 bbl of water is produced. Produced water consists of various amounts of organic and inorganic constituents from the source geologic formation and associated hydrocarbons. Produced-water handling has become a major effort for all waterflood operations. Membrane technology has been widely used for produced-water purification because of its economic and portable properties. However, the presence of organic matter in produced water causes serious membrane fouling, which shortens membrane life and increases operation costs. In this study, to reduce organic components in produced water, we fabricated a series of polyethersulfone (PES)/cellulose acetate butyrate (CAB) hybrid hollow-fiber membranes (HFMs) with different polymer-mass ratio for the removal of organic matter (benzene, toluene, octanoic acid, and hexanoic acid) from produced water. The morphology of the hybrid PES/CAB HFMs was characterized by scanning electron microscope (SEM) and atomic force microscope (AFM). The performance of the hybrid PES/CAB HFMs was evaluated in terms of permeate-water flux (PWF), organic-matter-removal efficiency, flux-decline ratio (FDR), and flux-recovery ratio (FRR). The results revealed that the PES/CAB hybrid HFMs comprised open-ended selective layers with homogeneous CAB distribution. Compared with neat PES HFM, the PES/CAB hybrid membranes exhibited 20.3% improvement of PWF. The organics-removal efficiency was higher than 99.8% for all the membranes. With 1.74 wt% of CAB in PES dope solution, the hybrid membranes possessed the lowest FDR and highest FRR, indicating the excellent antifouling ability of the PES/CAB HFMs. Because of these results, a two-stage antifouling HFM nanofiltration process was proposed as a follow-up work. The PES/CAB hybrid HFMs could serve as an attractive alternative for removing organic matter from produced water.