Towards recyclable 2D material-based nanofiltration membranes for water purification Áine Coogan 1 , Natalia Garcia Doménech 1,2 , Donagh Mc Ginley 1 , Finn Purcell-Milton 1,2,3 , Yurii K. Gun'ko 1,2,4 1 School of Chemistry, Trinity College Dublin, Ireland, 2 BiOrbic Bioeconomy Research Centre, University College Dublin, Ireland, 3 School of Chemical and BioPharmaceutical Sciences, Technological University Dublin, Ireland, 4 AMBER Research Centre, Trinity College Dublin, Ireland One third of the world's population does not have access to clean water (WHO - 2019). This is due to various factors including increasing population density, urbanisation, climate change, and inequality, among others. 1 The development of new, inexpensive and reliable methods of the removal of various toxins and pollutants from water is therefore of the utmost urgency. In recent years, the emergence of new 2D nanomaterial based nanofiltration (NF) membranes has become an exciting prospect for water purification. In particular, boron nitride (BN) and oxidised BN (BNOx) have been previously shown to exhibit excellent performance for the removal of water-soluble organic dyes, that can often be leached into wastewater by the textile industry. 23, However, the widespread application of these membranes is currently limited, as they often suffer from membrane fouling and clogging, and are often single-use. Methods to improve the recyclability of these membranes are urgently needed. One such approach which has not been explored to date in the literature is the integration of photocatalytically active 2D materials, such as layered double hydroxides (LDH), into existing high-performance NF membranes. In this work, we present new high-performance hybrid copper-aluminium (CuAl) LDH/BNOx hybrid membranes. CuAl LDH nanosheets are synthesised by simple, water-based room temperature co-precipitation, and membranes are produced by ultrasonication with BNOx, followed by vacuum filtration-based deposition. 4 These membranes show excellent retention (96-100%) for several organic dyes. Kinetic studies under visible light conditions reveal that these membranes exhibit rapid photodegradation of the dyes due to the presence of photocatalytically active LDH. This approach addresses the problem of membrane fouling, allowing for full recovery of the original constituent nanomaterials. We believe that this work represents a significant step towards the goal of achieving high-performance, reusable, cost-effective nanofiltration membranes. References 1. Li, J., Zhang, S., Chen, Y., Liu, T., Liu, C., Zhang, X., Yi, M., Chu, Z., & Han, X. (2017). A novel three-dimensional hierarchical CuAl layered double hydroxide with excellent catalytic activity for degradation of methyl orange. RSC Advances , 7(46), 29051–29057. 2. Doménech, N. G., Purcell-Milton, F., Arjona, A. S., García, M.-L. C., Ward, M., Cabré, M. B., Rafferty, A., McKelvey, K., Dunne, P., & Gun’ko, Y. K. (2022). High-Performance Boron Nitride-Based Membranes for Water Purification. Nanomaterials 2022, Vol. 12, Page 473, 12(3), 473. 3. García Doménech, N., Coogan, Á., Purcell-Milton, F., Casasín García, M. L., Sanz Arjona, A., Brunet Cabré, M., Rafferty, A., Mckelvey, K., Dunne, P. W., & Gun’ko, Y. K. (2022). Partially oxidised boron nitride as a 2D nanomaterial for nanofiltration applications. Nanoscale Advances , 4(22), 4895–4904. 4. Coogan, Á., Hughes, L., Purcell-Milton, F., Cardiff, S., Nicolosi, V., & Gun’ko, Y. K. (2022). Two-Dimensional Chiroptically Active Copper Oxide Nanostructures. The Journal of Physical Chemistry C , 126(44), 18980–18987.
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