Fabrication of thin-film nanocomposite nanofiltration membranes incorporated with aromatic amine-functionalized multiwalled carbon nanotubes. Rejection performance of inorganic pollutants from groundwater with improved acid and chlorine resistance

A thin-film nanocomposite nanofiltration (TFN-NF) membrane was fabricated through blending a novel aromatic amine-functionalized multiwalled carbon nanotubes (AAF-MWCNTs) and an aliphatic amine-functionalized multiwalled carbon nanotubes (AF-MWCNTs). The polyamide layer was synthesised by interfacial polymerisation (IP) between piperazine and trimesoyl chloride monomers. The improved resistance of NF membranes to chlorine and acid were characterised by X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy, atomic force microscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, contact angle, and zeta potential measurements. XPS analysis confirmed chlorine and acid resistance properties, as well as an improvement in the polyamide network cross-linking degree of the new nanofiltration membranes incorporated with AAF-MWCNTs (AAF–NF). The membrane transport properties and the performance on the rejection of HAsO₄ ⁻², NO₃ ⁻, and NH₄ ⁺ from solutions mimicking polluted groundwater were evaluated. Membrane performance to the target pollutants were determined by the solution-electro-diffusion (SED) model coupled with reactive transport. The results showed that AAF–NF membranes, with long-lifetimes, could be applied for the removal of As(V) from polluted groundwater. Water permeate flux and the arsenic rejection of the AAF–NF membrane increased by 15% when it is compared with a typical commercial semi-aromatic polyamide nanofiltration membranes (Desal DL).