Eco-friendly lamellar structured graphene oxide-Lysine nanocomposite membranes with varying d-spacing for enhanced pervaporation desalination

Millions face water scarcity, making affordable desalination essential. Membranes, in particular pervaporation desalination membranes, especially GO-based membranes, are promising owing to their high salt rejection. However, issues like high tendency to swelling and selectivity-permeability trade-offs limited their commercial use. To address this challenge, lysine-intercalated GO nanocomposite membranes were developed for improving pervaporation desalination performance and stability of the GO membrane. These nanocomposite membranes were coated onto a nylon 66 substrate (pore size = 0.22 mu m). Key nanocomposite membrane physicochemical characteristics such as interlayer spacing (d-spacing), thickness of the membranes, hydrophilicity, and stability were found to significantly impact pervaporation desalination performance. Experimental findings indicate that lysine intercalation into GO increases both the interlayer spacing and the stability of the nanocomposite membrane. Moreover, lysine enhances the hydrophilicity of the nanocomposite membranes. Optimal performance for pervaporation desalination using GO-Lysine nanocomposite membranes was achieved at 30 degrees C and 60 min. The optimum GO-L0.1 nanocomposite membrane demonstrated superior performance with a NaCl rejection rate of over 99.99 % and a water flux of 66.27 +/- 0.86 kg m-2h-1 when tested using a 3.5 % NaCl solution at 70 degrees C. Additionally, the optimum GO-L0.1 nanocomposite membrane maintained consistent NaCl rejection and water flux over extended use. Consequently, GO-Lysine nanocomposite membranes show great potential compared to reported GO-Based membranes for pervaporation desalination applications.