Robust polyamide-based composite membrane with controllable graphene oxide post-modification via rod-coating for enhanced pervaporation desalination

Pervaporation (PV) desalination has received great attention as an emerging and efficient technology for treating high-salinity wastewater. The development of high-performance and robust PV membranes is the key issue. Herein, the classical interfacial polymerization (IP) process was applied to prepare dense fully-aromatic polyamide separation layers, and then graphene oxide (GO) with polyvinyl alcohol (PVA)-glutaraldehyde crosslinking was used to modify the prepared thin-film composite (TFC) membranes by rod-coating process. The characterization results for the surface composition and properties of the membranes indicate the successful introduction of GO coatings. Moreover, the micro-morphology of the membranes after GO post-modification shows a smooth surface, suggesting that the GO nanosheets cover the leaf-like structures of the PA layers. Due to the improved hydrophilicity of the GO-modified membrane and the fast mass transfer channels within the ultrathin GO layer (∼50 nm), the optimized membrane exhibits 22.6 L m−2 h−1 of water flux and 99.99 % of rejection under 70℃ and 3.5 % NaCl feed solution. The nonlinear fitting results based on the modified Arrhenius equation show that the apparent activation energy for water transmission of the optimal membrane decreases by 13.6 % compared with the control one. In addition, the robustness of the composite membrane based on IP and rod-coating process was evaluated and elucidated in detail. The mass transfer process in PV desalination was also discussed by comparing polyamide-based and PVA-based membranes, which will encourage researchers to further explore TFC membranes based on IP process suitable for PV desalination.