Thin Film Nanofibrous Composite Ultrafiltration Membrane for Oil Removal from Oilfield Wastewater

Nanofibrous substrate composite ultrafiltration membrane consisted of polyacrylonitrile (PAN) electrospun scaffold which was used as the substrate, and a thin crosslinked poly(vinyl alcohol) (PVA) barrier layer which was prepared by electrospinning technique combined with mixed solvent treatment. The thickness of PVA nanofibrous top layer was controlled by changing the electrospun depositing time. Through immersing PVA/PAN double-layer mats into water/acetone mixed solvent system, the PVA nanofibrous top layer was swollen to merge imperceptibly into an integrated barrier film on the surface of PAN substrate, and then chemically crosslinked by glutaraldehyde. The resultant PVA/PAN thin film nanofibrous composite (TFNC) membrane has high rejection rate (99.6%), high flux (410.5l/m2h) and good anti-fouling characteristic at very low operation pressure (0.2MPa) for separating oil from the oilfield wastewater. Additionally, the removal of TDS, suspended matter, total iron and sulfate reducing bacteria (SRB) showed high rejection rate with relatively stable PH.