Nanodiamond mediated interfacial polymerization for high performance nanofiltration membrane

Introducing nanomaterial in interfacial polymerization (IP) system for nanofiltration (NF) membrane synthesis has witnessed a remarkable performance enhancement thus drawing intensive attention. However, the underlying mechanism for nanomaterial induced performance enhancement is still unclear due to the lack of study on nanoparticle dispersity and architecture at polymerization interface. Using nanodiamond (ND) as the example, this study demonstrates nanoparticle undergoes aggregation preferably at the reaction interface and the architecture of ND particles has a direct impact on membrane structure and performance. Through proactively controlling the aggregation extent while employing these ND clusters as the nano-template, the feature morphology of NF membrane is transformed from nodules to ridges at the nanoscale. Such transformation generates a significant augmentation of effective membrane area, leading to the increase of water permeance by 70%. With a low amount of nanodiamond addition (<0.1 wt%), the NF membrane can achieve a high water permeance of 150 L m⁻² h⁻¹ MPa⁻¹ with ~98% rejection of Na₂SO₄. Moreover, the introduction of nanodiamond makes the nanofiltration membrane more hydrophilic, with water contact angle decreased from 50° to 35°. The comparison with contemporary nanofiller studies indicates our nanodiamond strategy yields some of the best performance enhancement.