Nanostructured materials for water desalination

Abstract

Desalination of seawater and brackish water is becoming an increasingly important means to address the scarcity of fresh water resources in the world. Decreasing the energy requirements and infrastructure costs of existing desalination technologies remains a challenge. By enabling the manipulation of matter and control of transport at nanometer length scales, the emergence of nanotechnology offers new opportunities to advance water desalination technologies. This review focuses on nanostructured materials that are directly involved in the separation of water from salt as opposed to mitigating issues such as fouling. We discuss separation mechanisms and novel transport phenomena in materials including zeolites, carbon nanotubes, and graphene with potential applications to reverse osmosis, capacitive deionization, and multi-stage flash, among others. Such nanostructured materials can potentially enable the development of next-generation desalination systems with increased efficiency and capacity.

Desalination of seawater ion complexes by MFI-type zeolite membranes: Temperature and long term stability

“…4), the effect of osmotic pressure reduced the effective pressure by 32% correlating well with the observed flux reduction. Figure 2 shows the specific flux which was estimated according to the following equations: [33]. While the flux achieved in this study is practically too low for industrial applications, we acknowledge that zeolite membranes synthesised by the in-situ method (thickness ~3 µm) [6,7] are much thicker than commercial RO membranes (0.2 µm) [34,35].…”

Time-dependent ion selectivity in capacitive charging of porous electrodes

“…In commercial desalination technologies, such as reverse osmosis and multistage flash distillation, freshwater is produced at relatively high energy cost and often requires re-mineralization for human consumption. For brackish water or wastewater it can be advantageous to use a different type of technology, namely techniques where ions are removed from the feed water under the influence of electrical field effects, such as in electrodialysis [8,9], capacitive deionization [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28], membrane capacitive deionization [29][30][31][32][33][34], desalination using microchannels [35], batteries [36], microbial desalination cells [37] and wires [38]. Such techniques have the potential to be energy-efficient as they focus on the removal of the (often relatively few) ions in the water to obtain freshwater in this way.…”

Spray Layer-by-Layer Assembled Clay Composite Thin Films as Selective Layers in Reverse Osmosis Membranes

“…To address this trade-off, researchers have investigated the use of nanostructured materials that enable less-hindered water transport while still providing mechanisms for salt rejection in the membrane 22 . The literature on nanostructured materials for RO membranes contains experimental and theoretical work on selective layers using carbon nanotubes 23 , graphene 24 , metal oxide nanoparticles [25][26] , and zeolites 27 with varying degrees of success.…”