Enhancement of lignin-modified nanofiltration membranes performance via acyl chloride crosslinking post-treatment

Nowadays, the discharge of pharmaceutical wastewater and the overuse of antibiotics have resulted in the accumulation of antibiotic residues in water body, posing a severe threat to environment and human health. Nanofiltration (NF) membranes, due to their selective permeability, have been widely applied in the removal of antibiotics. However, it is significant to replace the monomers produced by fossil resources in interfacial polymerization with renewable monomers. To address this challenge, lignin was incorporated as a biomass-source modifier into the interfacial polymerization process. Lignin-based NF membranes were crosslinked with diacyl chlorides to enhance their rejection performance. To enhance membrane performance, the acyl chloride selection was optimized, and the influence of molecular chain length variation in linear diacyl chlorides on membrane crosslinking characteristics was investigated. Membrane properties were thoroughly evaluated through permeability tests, along with characterizations including infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. These analyses shed light on the impact of reaction conditions on membrane performance and the underlying reaction mechanisms. The results demonstrated that the membrane crosslinked with glutaroyl chloride achieved a significant increase in Na₂SO₄ rejection, from 90.2 % to 96.7 %, and exhibited excellent rejection (>95 %) for various antibiotics. This study not only expands the use of biomass materials in the fabrication of NF membranes but also provides a new strategy for the development of high-performance membranes.