Removing the trace organic compounds using graphene oxide nanocomposite membrane cross-linked by melamine

Abstract

In this study graphene oxide (GO) based active layer was formed on microfiltration substrate to prepared thin file composite forward osmosis (TFC-FO) membrane with high rejection to pesticides. The ideal GO-based membrane should have high stability, durability, and selectivity. To improve the stability of GO based TFC membrane in aqueous solution the GO nanosheets were cross-linked with melamine monomer. An anchoring carbon-nitrogen covalent bond between the GO nanosheets and melamine molecules is thought to supplement to form the nanocomposite structure. As a result of the configuration of melamine molecules within the channel region, a nanocomposite structure has been formed which provides an optimal condition for resisting the flow of hydrated salt ions but creating a pathway for water molecules to flow. According to the FO tests with different draw solutions against DI water feed, the prepared GOM membranes (GO based active layer crosslinked with melamine) showed best performance with trisodium citrate (TSC) draw solution. In the FO model, a water flux of 18.1 LMH was obtained using TSC, which was 970% higher than the NaCl, while the reverse solute diffusion was reduced by 1100%. The effect of GO thickness on FO performance was also studied, by changing GO solution volume during active layer coating (10, 15 and 20 mL GO solution with concentration of 0.1 mg/mL). Result showed that by increasing the GO thickness the water flux increased from 13.7 LMH in GOM.10 to 18.1 in GOM.15. In addition, the nanocomposite membrane shows high rejection against of both diazinon (99.4%) and atrazine (97.3%). In relation to these results, it can be concluded that GO-based membranes can provide clean water in the FO process as an alternative to polymer-based TFC membranes.