Improving permeability and anti-fouling performance in reverse osmosis application of polyamide thin film nanocomposite membrane modified with functionalized carbon nanospheres

In this study, carboxyl group-functionalized carbon nanospheres (CNs-COOH) and silver-coated products (CNs-COOH/Ag) were successfully realized and used as nanofillers to fabricate thin-film nanocomposite (TFN) membranes via the interfacial polymerization of m-phenylenediamine (MPD) and trimesoyl chloride (TMC) solutions. The structure of the functionalized CNs modified TFN membranes (TFN-Cs-COOH, TFN-Cs-COOH/ Ag) was significantly different from that of the CNs modified TFN (TFN-Cs) and TFC membranes, as the carboxyl groups in the nanofillers strongly influence the process of interfacial polymerization. The permeability and antifouling performances of the TFN membranes were significantly enhanced owing to the changes in the membrane structure. The water fluxes of the TFN-Cs-COOH and TFN-Cs-COOH/Ag membranes were respectively 91.9% and 73.2% higher than that of the TFC membrane, with the NaCl rejection exceeding 96%. The nanofillers of CNs-COOH/Ag with monodispersed silver nanoparticles (NPs) resulted in outstanding anti-bacterial performance in the TFN-Cs-COOH/Ag membrane. Overall, this work demonstrates that, when functionalized carbon NPs are used as nanofillers, the practical performance of TFN membranes can be improved for reverse osmosis.