Fabrication of a Novel Nanofiltration Membrane with Enhanced Performance via Interfacial Polymerization through the Incorporation of a New Zwitterionic Diamine Monomer

Abstract

It is known that the polyamide (PA) barrier layer’s inherent microstructure and surface physicochemical properties of thin film composite nanofiltration membrane are crucial for its separation performance. Herein, we designed and synthesized a new zwitterionic aromatic diamine monomer 3-(4-(2-((4-aminophenyl)­amino)­ethyl)­morpholino-4-ium)­propane-1-sulfonate (PPD-MEPS) through a three steps reaction, and this hydrophilic molecule was incorporated into the active layer to tailor the poly­(piperazine-amide)-based nanofiltration membranes with significantly improved water permeability and antifouling properties. As a p-phenylenediamine (PPD) derivative, PPD-MEPS possesses two active amine units, which can react with trimesoyl chloride in the organic phase during the interfacial polymerization reaction process. Thus, the super-hydrophilic zwitterions were not only on the membrane surface but also across the whole PA layer to facilitate water molecule transportation. The successful augmentation of zwitterions into the PA layer was well illustrated by attenuated total reflectance–Fourier transform infrared spectroscopy (ATR–FTIR) results and X-ray photoelectron spectroscopy analysis. With increasing loading content of PPD-MEPS in PIP aqueous solution, the as-fabricated nanofiltration membranes (NFMs) exhibited higher hydrophilicity, increased active layer thickness, and molecular weight cut off. When the zwitterionic monomer reached 60% to PIP for NFM-4, the water permeability went up to 9.82 L m–2 h–1 bar–1, increasing by 45%; meanwhile, the Na2SO4/NaCl selectivity increased from 2.54 to 4.03. In addition, the fouling experiments illustrated that the fouling resistance of the zwitterion-modified NFMs to bovine serum albumin was significantly improved.

Nanofiltration Membranes with Octopus Arm-Sucker Surface Morphology: Filtration Performance and Mechanism Investigation

“…(e) Trade-off relationship between water/salt selectivity (A/B) and water permeance (A). (f) Summary of water permeance and Na 2 SO 4 rejection of TFC NF membranes reported in previous literature. ,,,− Error bars indicate the standard deviation ( n = 6).…”

Inner Surface Hydrophilic Modification of PVDF Membrane with Tea Polyphenols/Silica Composite Coating

“…Therefore, hydrophilic modification of the hydrophobic membrane is of vital importance. Many efforts such as blending [ 15 , 16 , 17 , 18 ], grafting [ 19 , 20 ], co-polymerization [ 21 , 22 , 23 , 24 ] and layer-by-layer assembly [ 25 , 26 , 27 ] methods have been devoted to improving the hydrophilicity of the membrane. However, these methods may require special equipment or complicated conditions, and have certain limitations in practical applications.…”

Preparation and modification of thin film composite membrane using a bulky dianhydride monomer

“…19 As an example, introducing bulky monomers in interfacial polymerization (IP) procedure during TFC membrane preparation is an effective way to tune pore dimension and size and charge the membrane surface at the same time. 20 Recently, various diamine containing hydrophilic groups (e.g., sulfonic acid, 21 zwitterion, 22 and carboxylic acid 18 ) have been employed as co-reactants of customary diamine of TFC membrane meta phenylene diamine and piperazine (PIP) to react by organic phase (trimesoyl chloride [TMC]), intended to fabricate a better TFC membrane. These hydrophilic groups are valuable for improving membrane permeability and hydrophilicity.…”