Jiaojiao Zhao

Antifouling, High-Flux Nanofiltration Membranes Enabled by Dual Functional Polydopamine

A facile method for fabricating antifouling and high-flux nanofiltration (NF) membranes was developed based on bioinspired polydopamine (PDA). Polyethersulfone (PES) ultrafiltration membrane as the support was first deposited a thin PDA layer and then chemically modified by a new kind of fluorinated polyamine via Michael addition reaction between fluorinated polyamine and quinone groups of PDA. PDA coating significantly reduced the pore sizes of the PES support membrane and endowed the NF membrane with high separation performance (flux about 46.1 L/(m(2) h) under 0.1 MPa, molecular weight cutoff of about 780 Da). The grafted fluorinated polyamine on the PDA layer could form low free energy microdomains to impede the accumulation/coalescence of foulants and lower the adhesion force between foulants and the membrane, rendering the membrane surface with prominent fouling-release property. When foulant solutions (including bovine serum albumin, oil and humic acid) were filtered, the resultant NF membrane exhibited excellent antifouling properties (the minimal value of total flux decline ratio was ∼8.9%, and the flux recovery ratio reached 98.6%). It is also found that the structural stability of the NF membrane could be significantly enhanced due to the covalent bond and other intermolecular interactions between the PDA layer and the PES support.

Improved oil/water emulsion separation performance of PVC/CPVC blend ultrafiltration membranes by fluorination treatment

AbstractThe introduction of perfluoroalkyl groups played an important role in enhanced antifouling ability in oil/water emulsion membrane separation. Polyvinyl chloride (PVC) and chlorinated polyvinyl chloride (CPVC) blend membranes were used to prepare the novel fluorinated membranes. Amination treatment of PVC/CPVC blend membranes was first carried out through chemical grafting with ethylenediamine (EDA). Fluorination treatment was then achieved through chemical reaction between the redundant amino group of EDA and the carboxyl group of pentadecafluorooctanoica acid. The component of the fluorinated membrane surfaces was measured by X-ray photoelectron spectroscopy. The structure change was observed by scanning electron microscope. The fluorinated membranes were fully wetted by water in short time according to water contact angle measurement. The fluorinated membranes had higher permeate fluxes and higher flux recovery than PVC/CPVC blend membranes in oil/water emulsion membrane separation.