(398aw) Nano-Cellulose Based Thin Film Nanocomposite RO Membranes with Tunable Flux Via Control of Interfacial Transport

Improvement of current
reverse osmosis membranes poses an intricate challenge that, if solved, could
affect global access to clean water. Thin film composite (TFC) membranes are
used commonly in industrial desalination processes, relying on a polyamide layer
for selectivity. It is desired to improve the energy efficiency of these
membranes in order to lower the production cost of clean water. Recent studies
in our research group involving the addition of functionalized carbon nanotubes
to the selective polymer layer of existing TFC membranes have shown promising
results, yielding higher water permeance (flux), improved chemical resistance,
anti-biofouling properties, and mechanical property enhancement. These thin
film nanocomposite (TFN) membranes are often cost-ineffective, prompting the
search for an economically viable alternative. TEMPO-oxidized cellulose
nanocrystals (TOCNs) have been investigated as a possible TFC additive due to
their hydrophilicity, availability, and low cost. In the current work, TOCNs are
deposited within the selective aromatic polyamide layer of an established TFC
membrane design and subjected to reverse osmosis conditions to determine the water
flux and salt rejection, and to observe the properties of the surface. Significant
increases in water permeance have been observed while maintaining high salt
rejection when compared to a control polyamide (PA) TFC membrane. The improved
flux confirms that high aspect ratio nanoparticles can be used to improve
transport in membranes via the creation of pathways for rapid transport at the
interface between the particles and polymer matrix. This suggests that membrane
properties can be controlled and optimized via careful control of the
nanoparticle/polymer interface (i.e. through control of nanoparticle surface
functionality and polymer matrix properties.

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