Superhydrophilic In-Situ-Cross-Linked Zwitterionic Polyelectrolyte/PVDF-Blend Membrane for Highly Efficient Oil/Water Emulsion Separation

Abstract

Because of weak hydrophilicity, membranes always experience fouling problems during separations. This phenomenon seriously impedes the development of membrane technologies for practical industrial-oil wastewater treatment. In this work, we successfully fabricated a superhydrophilic zwitterionic poly(vinylidene fluoride) (PVDF) membrane using a two-part process with an in situ cross-linking reaction during nonsolvent-induced phase separation and a subsequent sulfonation reaction. To prepare this zwitterionic PVDF membrane, a copolymer poly(dimethylaminoethyl methacrylate-co-2-hydroxyethyl methacrylate) (PDH) was synthesized as a zwitterionic polymer precursor and used as an additive in membrane preparation. This zwitterionic additive is well-immobilized in the membrane using in situ cross-linking to ensure the long-term stability of the membrane, and subsequent sulfonation transforms the precursor to a zwitterionic polymer to produce a superhydrophilic membrane. This superhydrophilic zwitterionic PVDF membrane exhibits high water permeation flux and good antifouling properties for separating oil-in-water emulsions with high separation efficiency.

Preparation of Fouling-Resistant Nanofibrous Composite Membranes for Separation of Oily Wastewater

“…Membranes are the most important part of the microfiltration process [8]. For instance, it was found that superhydrophilic in situ-crosslinked zwitterionic polyelectrolyte/polyvinylidene fluoride-blend membranes exhibit high water permeation flux and good antifouling properties for separating oil-in-water emulsions with high separation efficiency [9]. Cao et al prepared hyperbranched polyethyleneimine (HPEI) glass fiber membranes for oil-water separation.…”

Polypropylene Nonwoven Fabric@Poly(ionic liquid)s for Switchable Oil/Water Separation, Dye Absorption, and Antibacterial Applications

“…When aw ater droplet is in contact with the PP@PIL-Br fabric, it immediatelys preadso ut and infiltrates into the fabric, showingaCA of 08 ( Figure 2b). [22] Roughness is ak ey factor for superhydrophobic properties. The changed chemical composition greatly enhanced the hydrophilicity of the corona chargedP Pf abric.…”

“…These trapped water molecules greatly reduced the contact areas between the oil and the PP@PIL-Br fabric surface, resulting in ah igh oil CA in water. [22] Roughness is ak ey factor for superhydrophobic properties. The surfacer oughness is characterized by atomic force microscopy (AFM).…”

“…[1,2] However the constituents of wastewater,i ncluding oils, [3][4][5] dyes, [6][7][8] and bacteria, [9,10] are usually complex, making wastewater cleanup difficult. [21][22][23] Therefore, preparing smart oil/water separation materials with switchable wetting behaviorh as received attentionb ecause it involves a simple low-energy process with high separation efficiency.F or example, Xue and co-workers fabricated superamphiphilic PVDF membrane with switchable transport performance. Oil/water separation techniques have attracted attention to address environmental concerns caused by the leakage of industrial organic pollutants and oils into the aquatic environment.…”

“…However,s uperhydrophobic oleophilic materials usually suffer from deactivationb yh igh-viscosity oil and coagulation of fat after long-term application. [21][22][23] Therefore, preparing smart oil/water separation materials with switchable wetting behaviorh as received attentionb ecause it involves a simple low-energy process with high separation efficiency.F or example, Xue and co-workers fabricated superamphiphilic PVDF membrane with switchable transport performance. [12] The membrane is applicable to the separationo fo il-in-water and water-in-oil.…”