Recent Advances in the Fabrication of Membranes Containing “Ion Pairs” for Nanofiltration Processes

Abstract

Abstract:In the face of serious environmental pollution and water scarcity problems, the membrane separation technique, especially high efficiency, low energy consumption, and environmental friendly nanofiltration, has been quickly developed. Separation membranes with high permeability, good selectivity, and strong antifouling properties are critical for water treatment and green chemical processing. In recent years, researchers have paid more and more attention to the development of high performance nanofiltration membranes containing "ion pairs". In this review, the effects of "ion pairs" characteristics, such as the super-hydrophilicity, controllable charge character, and antifouling property, on nanofiltration performances are discussed. A systematic survey was carried out on the various approaches and multiple regulation factors in the fabrication of polyelectrolyte complex membranes, zwitterionic membranes, and charged mosaic membranes, respectively. The mass transport behavior and antifouling mechanism of the membranes with "ion pairs" are also discussed. Finally, we present a brief perspective on the future development of advanced nanofiltration membranes with "ion pairs".

Development of ZSM-22/Polyethersulfone Membrane for Effective Salt Rejection

“…This assessment led to cheaper water softening applications using lower applied pressure (<1 bar) in the NF or RO membrane systems. The interaction of these solutes with the composite membrane matrix containing negatively charge nanoadditives, as opposed to size exclusion, was also a possible mode for membrane rejection [84,85]. The relatively high charge on divalent Mg ion means it is strongly attracted to the negatively charged membrane surface than the monovalent Na ion, resulting in the different observed rejection profiles.…”

Separation of Volatile Fatty Acids from Model Anaerobic Effluents Using Various Membrane Technologies

“…The Layer-by-Layer (LbL) method represents a unique NF membrane fabrication technique where polycations and polyanions are alternatingly layered on a charged substrate, typically an ultrafiltration membrane (UF) to build a dense amorphous polyelectrolyte multilayer (PEM), which acts as the active separation layer. The high charge density of the PEM leads to a high monovalent salt passage, a relatively greater rejection of organics and, if the membrane has a high surface charge, a high mono/divalent salt selectivity [ 19 , 20 , 21 , 22 ]. PEM membranes have further advantages compared to polyamide membranes, which originate from the different chemistry: a much higher resistance to oxidants, such as chlorine, a higher pH tolerance [ 23 ], high self-healing ability [ 24 , 25 , 26 ] and, if the substrate allows, solvent resistance [ 27 , 28 ].…”

In Situ Raman Spectroscopy as a Tool for Structural Insight into Cation Non-Ionomeric Polymer Interactions during Ion Transport

“…The key elements in such systems are ion exchange membranes (IEMs) which play a vital role as a cation or anion conductor, an electrical insulator between anode and cathode, and a separator between the fuel (methanol) and oxidant (oxygen or air). IEMs can be made either from pure polymer membranes or from composite membranes, where other materials are embedded in a polymer matrix [ 8 , 9 , 10 , 11 , 12 ].…”