(367f) Influence of Graphene Quantum Dot Surface and Pore Modification on Membrane Fouling

Membranes have been widely utilized for many applications including water softening, pharmaceutical purification, and dairy processing. In systems with organic foulants or sparingly soluble salts present, fouling of the membrane surface leads to reduced performance and shortened membrane lifespans. Graphene oxide has been of great interest as an antifouling material for membrane modification due itâ??s inherit hydrophilicity and the presence of negatively charged carboxyl groups. Graphene oxide quantum dots are highly hydrophilic particles that maximize functionality in a size (1-3 nm) that makes them a particularly interesting candidate for membrane functionalization.

In this work, the benefits of GQD modification toward surface fouling behavior and pore blockage by organic foulants will be studied. Through EDC/NHS coupling, GQDs were covalently bonded to the surface of nanofiltration membranes. Zeta potential analysis shows higher negative surface charge properties after GQD coupling and increased rejection of Na₂SO₄ (97% compared to 76% for the standard membrane). The GQD coupled membrane exhibits double the normalized flux after 2 ½ hours of recovery of solution containing 400 ppm BSA when compared to the standard membrane.

GQDâ??s were integrated throughout the pore structure of cellulose ultrafiltration membranes by means of phase inversion. A common ionic liquid solvent between GQDs and cellulose membranes was used to deter aggregation and promote the selective entrapment of GQD in the membrane pore network. The effect of water flux, selectivity and antifouling behavior for BSA will be studied.

Acknowledgements

The author acknowledges the support of the Southern Company in funding and collaboration, and additional funding from the National Science Foundation EPSCoR for funding. Nanostone Membrane of Oceanside, CA has provided support and collaboration in the development of membranes and spiral wound membrane modules.