p-Phenylenediamine-grafted multi-walled carbon nanotubes as a hydrophilic modifier in thin-film nanocomposite membrane

In this paper, an efficient thin-film nanocomposite (TFN) membrane was synthesized by interfacial polymerization and used for water desalination. Piperazine (PIP) and trimesoyl chloride were used as monomers, and p-phenylenediamine-grafted multi-walled carbon nanotube (p-PDA-MWCNT) was used as a hydrophilic modifier to enhance the performance of the polysulfone nanofiltration membrane. In order to characterize the synthesized p-PDA-MWCNTs, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis and electron-dispersive spectroscopy were used. In order to enhance the performance of the membrane, different concentrations of p-PDA-MWCNTs (0.01, 0.02, 0.04, 0.05 and 0.075 wt%) were added to the PIP solution to prepare p-PDA-MWCNTs-embedded membranes. To check the performance of the modified membrane, solutions of 1000 mg L⁻¹ Na₂SO₄, MgSO₄, NaCl and CaCl₂ were tested. The results show that TFN-modified membrane provides excellent water permeability and also salt rejection in the presence of 0.02 wt% p-PDA-MWCNTs which shows superior improvement in TFN membrane.