The Polymer Nanofiltration Membrane Group of the Institute of Membrane Science and Technology of Nanjing Tech University has recently developed a new solvent-resistant nanofiber composite membrane. The support layer prepared by the technician using the high-pressure solution electrospinning method has low resistance and high flux, and forms a stable three-dimensional crosslinked structure between the polymer chains by chemical crosslinking method, which greatly improves the mechanical properties of the membrane and the polar solvent. Chemical stability and solvent flux. This new membrane path is expected to break through the bottleneck in the application of solvent-resistant membranes.
Professor Sun Shipeng, who in charge of the project, said: “The solvent-resistant nanofiltration membrane is the only way to efficiently separate and recover organic solvents and high value-added products by membrane method. After mass production, the operating cost will be greatly reduced. We are confident to industrialize it. Finally brought to market.”
According to reports, the research group used a high-pressure solution electrospinning method to deposit loose polyacrylonitrile (PAN) felt on tin foil, and obtained a smooth and flat membrane surface by hot pressing method, and chemically cross-linked in hydrazine hydrate solution. The modified PAN base film with good solvent resistance is prepared by interfacial polymerization to obtain a polyamide selective layer. Under the action of special membrane structure, the mechanical strength of cross-linked PAN nanofiber base film is 20 times stronger than that of traditional phase-converted PAN film. Under the premise of the same interception rate, the pure water flux of nano-fiber composite film reaches self-made asymmetric composite. 9 times the film shows the low film resistance of the nanofiber film.
“The nanofiber composite membrane also has good performance in the solvent system. Under the premise of not implying the rejection, the membrane can still reach the flux of 10LMH/BAR in methanol, and the performance is better than most literature values under similar conditions.” the research team said. The membrane was able to maintain good stability after running for 48 hours in dimethyl sulfoxide (DMSO), indicating that the nanofiber membrane has a good application prospect in organic solvent systems.
It is understood that organic solvents such as methanol and dimethyl sulfoxide are widely used in many processes such as chemical separation, organic synthesis of fine chemical products, extraction of active pharmaceutical ingredients, and separation and purification of high value-added products. Distillation, extraction and other methods traditionally used for separation and recovery of these organic solvents have disadvantages such as high energy consumption and large solvent loss. The polymer solvent-resistant nanofiltration membrane has become a research hotspot because of its high separation precision and strong operability. However, although there are many application advantages of polymer nanofiltration, there are still some bottlenecks that limit its application. For example, polymer materials have poor solvent resistance, easy to swell or dissolve in solvents, and due to the dense structure of traditional phase inversion membranes, The higher membrane resistance leads to a generally lower solvent flux for conventional solvent-resistant composite membranes.
