Functionalized Graphene Oxide Modified Polyethersulfone Membranes for Low-Pressure Anionic Dye/Salt Fractionation

Area of Science:

• Materials Science
• Membrane Technology
• Environmental Engineering

Background:

• Graphene oxide (GO) membranes are promising for separation processes.
• Functionalization is key to enhancing membrane performance and selectivity.
• Developing efficient methods for dye and salt separation remains a challenge.

Purpose of the Study:

• To fabricate polyelectrolyte assembled functionalized graphene oxide (PE-GO) membranes.
• To investigate the impact of polydopamine (PDA) and ionic liquid (IL) functionalization on membrane properties.
• To evaluate the performance of these membranes in dye/salt separation and cleaning.

Main Methods:

• One-step charge-facilitated deposition for PE-GO membrane fabrication.
• Intercalation of PDA and IL functional moieties into GO membranes.
• Characterization of pore size, water flux, and separation performance.
• Assessment of membrane cleaning efficiency at different pH conditions.

Main Results:

• PE-GO membranes functionalized with PDA (PE-pGO) and IL (PE-iGO) showed increased pore sizes (4.13 nm and 6.54 nm, respectively) compared to pristine PE-GO (2.69 nm).
• Water flux increased significantly with functionalization, reaching 52.1 L m⁻¹ h⁻¹ bar⁻¹ for PE-iGO.
• PE-iGO membranes exhibited high water permeability (28.3–38.3 L m⁻¹ h⁻¹ bar⁻¹) at low operating pressures (0.5–2 bar).
• IL functionalization enhanced alkaline washing efficiency due to pH-dependent dye elution, while PDA functionalization hindered it.

Conclusions:

• Polyelectrolyte assembly with PDA and IL functionalization effectively enhances GO membrane performance for dye/salt separation.
• IL-functionalized membranes offer superior water permeability and improved cleanability.
• The choice of functional moiety significantly impacts membrane adsorption properties and cleaning efficiency.