Incorporation of layered double hydroxide nanofillers in polyamide nanofiltration membrane for high performance of salts rejections

Abstract

In this work, thin film composite (TFC) membrane embedded with self-synthesized layered double hydroxide (LDH) nanofillers was prepared via interfacial polymerization technique for nanofiltration (NF) process. Prior to filtration experiments, the morphologies and physicochemical properties of the prepared LDH nanofillers and TFC membranes were characterized using TEM, XRD, FESEM, FTIR, AFM, zeta potential analyzer and contact angle goniometer. The results revealed that the self-synthesized LDH nanofillers possessed layered structured materials with typical hexagonal plate-like shape. Meanwhile, it was found that the membrane contact angle decreased remarkably from 53° to 33.96° upon addition of 0.1 wt% LDH nanofillers in the active polyamide layer. TFN membrane of 0.1 wt% LDH loading possessed the highest water flux of 54.62 Lm −2 h −1 at 7 bar. The highest rejections of Na 2 SO 4 (97.3%), MgSO 4 (95.5%), MgCl 2 (95.2%) and NaCl (63.7%) were also achieved by the TFN embedded with 0.1 wt% LDH in polyamide layer. In addition to the excellent water flux and rejection, incorporation of LDH also enhanced the fouling resistance, proven by the improvement of pure water flux recovery by 52% after BSA filtration. The findings indicated the potential of the newly developed TFN membrane incorporated with LDH nanofillers for efficient NF membrane in water softening and pre-desalination process.