Design of a novel poly(aryl ether nitrile)-based composite ultrafiltration membrane with improved permeability and antifouling performance using zwitterionic modified nano-silica

Zwitterionic nano-silica (SiO₂ NPs) obtained by lysine surface modification was used as a hydrophilic inorganic filler for preparing a poly(aryl ether nitrile) (PEN) nanocomposite membrane via an immersion precipitation phase inversion method. The effects of zwitterionic SiO₂ NPs addition on the morphology, separation and antifouling performance of the synthesized membranes were investigated. Zwitterionic surface modification effectively avoided the agglomeration of SiO₂ NPs. The PEN/zwitterionic SiO₂ NPs composite membranes exhibited improved porosity, equilibrium water content, hydrophilicity and permeability due to the introduction of hydrophilic SiO₂ NPs in the casting solution, and the optimal pure water flux was up to 507.2 L m⁻² h⁻¹, while the BSA rejection ratio was maintained at 97.4%. A static adsorption capacity of 72.9 μg cm⁻² and the FRR up to 85.3% in the dynamic antifouling experiment proved that the introduction of zwitterionic SiO₂ NPs inhibited irreversible fouling and enhanced the antifouling ability of the PEN membrane.

Zwitterionic nano-silica (SiO₂ NPs) obtained by lysine surface modification was used as a hydrophilic inorganic filler for preparing a poly(aryl ether nitrile) (PEN) nanocomposite membrane via an immersion precipitation phase inversion method.

Fabrication of ultrafiltration membranes by poly (aryl ether nitrile) with poly (ethylene glycol) as additives

A new kind of flat sheet ultrafiltration membrane was prepared by a promising membrane material, poly (aryl ether nitrile) (PEN), via non-solvent induced phase separation. The effect of solvents, N-methyl-2-pyrrolidone (NMP) and dimethyl acetamide (DMAc), as well as additive of poly (ethylene glycol) (PEG) with different molecular weights on the structure and permeation performance of synthesized membranes were investigated. Comparing with NMP, DMAc is more suitable for the casting solution preparation due to better solubility. A gradually changing pore from sponge-like to finger-like can be observed when PEG was added with DMAc as solvent, while a finger-like pore structure always appears in the NMP system with or without PEG. In both systems, the formation of macrovoids is effectively promoted by the addition of PEG, and higher porosity membranes can be obtained by PEG with higher molecular weight. With the increase of PEG molecular weight from 400 to 10,000 Da, the permeate flux increases from 74.5 to 114.3 L·m^-2·h^-1 and from 102.0 to 130.8 L·m^-2·h^-1 under a 100 kPa pressure-driven when NMP and DMAc were used as solvents, respectively. The membranes prepared by DMAc exhibit outstanding rejection of BSA with rejections all above 96.5%.