Functionalized graphene-based polyamide thin film nanocomposite membranes for organic solvent nanofiltration

This work deals with the use of octadecylamine (ODA)-functionalized reduced graphene oxide (rGO) for thin film nanocomposite (TFN) membranes. The functionalization of rGO with ODA leads to graphene-based nanofillers, more hydrophobic than GO, and thus to the easier dispersion in the organic phase of the interfacial polymerization (IP) reaction carried out to produce polyamide (PA) TFN membranes. The performance of the new TFN membranes is evaluated by organic solvent nanofiltration (OSN) of alcoholic solutions containing dyes Acridine Orange (AO, MW 265 g·mol−1), Sunset Yellow (SY, MW 452 g·mol−1) and Rose Bengal (RB, MW 974 g·mol−1). The functionalized nature of the nanoparticles introduced into the hydrophilic PA layer allows an increase of the ethanol permeance from 2.8, 3.4 and 3.7 L·m−2·h−1·bar−1 for AO, SY and RB, respectively, corresponding to the bare thin film composite membrane (without rGO-ODA particles), to 4.3, 4.6 and 6.0 L·m−2·h−1·bar−1 for AO, SY and RB, respectively, for the rGO-ODA based TFN membrane. In fact, we hypothesize that the increase of the ethanol flux achieved with the use of rGO-ODA as a filler in TFN membranes is owing to a combination of the simultaneous presence of polar and non-polar groups from rGO-ODA nanosheets and the creation of still selective narrow gaps between these particles and the polyamide (PA).