(752a) Interfacial Transport in Nanocellulose-Based Nanocomposite Membranes for Improved Reverse Osmosis Performance

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 thin polyamide skin layer for selectivity.
Recent studies in our research group involving the addition of nanoparticles 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[1].
It is desired to understand how the addition of nanoparticles to the polyamide
skin layer influences polymer formation, thereby altering the transport
properties of the overall membrane. In addition, these thin film nanocomposite
(TFN) membranes are often cost-ineffective, prompting the search for an
economically viable alternative. Nanocellulose has become a popular field of
study given that it is produced on large scales globally in many different
varieties. In this study, cellulose nanocrystals (CNCs) of varying lengths are
explored as additives to TFN membranes. The high aspect ratios of the CNCs may
assist the formation of transport pathways for water molecules, as well as
improve the mechanical properties of the membranes. CNCs were deposited in situ
during polyamide skin layer formation in various amounts and the resulting
transport properties of the membranes were observed. Inclusion of CNCs has been
shown to increase flux by 20% while maintaining acceptable levels of salt
rejection, however, developing a consistent deposition method remains a
challenge.

Figure 1. Comparison of TFN
membrane performance between control (PA TFC) and various loading amounts of
TEMPO-oxidized CNCs (TOCNs) and CNCs as obtained. The best performance was
observed at a loading of 0.5 mg TOCNs.

[1] W. Chan, E.
Marand, S.M. Martin, Novel zwitterion functionalized carbon nanotube
nanocomposite membranes for improved RO performance and surface anti-biofouling
resistance, J. Memb. Sci. 509 (2016) 125–137. doi:10.1016/j.memsci.2016.02.014.