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M. H. Köhler et al.
origin. While fast flow in nanotubes is due to friction regardless of tube length,
in the case of 2D systems fast liquids transport is associated with their extremely
low thickness, and this phenomenon disappears as the layer grows beyond a certain
limit. Within single-layer surfaces, graphene is the material which not only has more
studies but is also more advanced in production. Nevertheless, TMDs exhibit water
permeability two to five orders of magnitude greater than the current technology
and 70% better than similar-sized graphene nanopores. These results demonstrate
how material chemistry (especially in nanopores) leads to exotic relationships with
water, which is attracted to the inner pore enhancing both water permeation and the
rejection of unwanted substances.
The actual nature of the TMD membranes’ higher permeability and ion rejection
is not clearly understood. In principle, the mix of hydrophobic and hydrophilic edges
are important ingredients, yet they do not explain why WS 2 shows water flux two
times greater than MoS 2 laminar membranes when both have a very similar charge
distribution.
TMD membranes can be constructed either by making pores in the perfect material
or by building up lamellar structures to employ filtration and adsorption qualities. In
both cases impact of defect, pore distribution, and thickness of the stacking layers
have to be explored together with the stability and toxicity of the material.
So far, what we have are prominent but diffuse experimental results. With the
help of theoretical and computational simulations—in addition to some creativity—
it is possible that in the near future both MoS 2 and WS 2 membranes can be used in
desalination plants, significantly improving their performance.
References and Future Reading
1. Majumder M, Chopra N, Andrews R, Hinds BJ (2005) Enhanced flow in carbon nanotubes.
Nature 438:44
2. Novoselov KS, Geim AK, Morozov S, Jiang D, Zhang Y, Dubonos SA, Grigorieva I, Firsov
A (2004) Electric field effect in atomically thin carbon films. Science 306:666–669
3. Novoselov KS, Geim AK, Morozov S, Jiang D, Katsnelson M, Grigorieva I, Dubonos S, Firsov
A (2005) Two-dimensional gas of massless dirac fermions in graphene. Nature 438:197–200
4. Ortiz-Medina J, Inukai S, Araki T, Morelos-Gomez A, Cruz-Silva R, Takeuchi K, Noguchi
T, Kawaguchi T, Terrones M, Endo M (2018) Robust water desalination membranes against
degradation using high loads of carbon nanotubes. Sci. Rep 8:2748
5. Jamali SH, Vlugt TJH, Lin L-C (2017) Atomistic understanding of zeolite nanosheets for
water desalination. J Phys Chem C 121:11273–11280
6. Dulebohn J, Ahmadiannamini P, Wang T, Kim S-S, Pinnavaia TJ, Tarabara VV (2014) Polymer
mesocomposites: ultrafiltration membrane materials with enhanced permeability, selectivity
and fouling resistance. J Membr Sci 453:478–488
7. Dong H, Zhao L, Zhang L, Chen H, Gao C, Ho WSW (2015) High-flux reverse osmosis
membranes incorporated with NaY zeolite nanoparticles for brackish water desalination. J
Membr Sci 476:373–383
8. Mouterde T, Keerthi A, Poggioli AR, Dar SA, Siria A, Geim AK, Bocquet L, Radha B (2019)
Molecular streaming and its voltage control in angstrom-scale channels. Nature 567:87–90
9. Bertolazzi S, Brivio J, Kis A (2011) Stretching and breaking of ultrathin MoS 2 . ACS Nano
5:9703–9709
M. H. Köhler et al.
origin. While fast flow in nanotubes is due to friction regardless of tube length,
in the case of 2D systems fast liquids transport is associated with their extremely
low thickness, and this phenomenon disappears as the layer grows beyond a certain
limit. Within single-layer surfaces, graphene is the material which not only has more
studies but is also more advanced in production. Nevertheless, TMDs exhibit water
permeability two to five orders of magnitude greater than the current technology
and 70% better than similar-sized graphene nanopores. These results demonstrate
how material chemistry (especially in nanopores) leads to exotic relationships with
water, which is attracted to the inner pore enhancing both water permeation and the
rejection of unwanted substances.
The actual nature of the TMD membranes’ higher permeability and ion rejection
is not clearly understood. In principle, the mix of hydrophobic and hydrophilic edges
are important ingredients, yet they do not explain why WS 2 shows water flux two
times greater than MoS 2 laminar membranes when both have a very similar charge
distribution.
TMD membranes can be constructed either by making pores in the perfect material
or by building up lamellar structures to employ filtration and adsorption qualities. In
both cases impact of defect, pore distribution, and thickness of the stacking layers
have to be explored together with the stability and toxicity of the material.
So far, what we have are prominent but diffuse experimental results. With the
help of theoretical and computational simulations—in addition to some creativity—
it is possible that in the near future both MoS 2 and WS 2 membranes can be used in
desalination plants, significantly improving their performance.
References and Future Reading
1. Majumder M, Chopra N, Andrews R, Hinds BJ (2005) Enhanced flow in carbon nanotubes.
Nature 438:44
2. Novoselov KS, Geim AK, Morozov S, Jiang D, Zhang Y, Dubonos SA, Grigorieva I, Firsov
A (2004) Electric field effect in atomically thin carbon films. Science 306:666–669
3. Novoselov KS, Geim AK, Morozov S, Jiang D, Katsnelson M, Grigorieva I, Dubonos S, Firsov
A (2005) Two-dimensional gas of massless dirac fermions in graphene. Nature 438:197–200
4. Ortiz-Medina J, Inukai S, Araki T, Morelos-Gomez A, Cruz-Silva R, Takeuchi K, Noguchi
T, Kawaguchi T, Terrones M, Endo M (2018) Robust water desalination membranes against
degradation using high loads of carbon nanotubes. Sci. Rep 8:2748
5. Jamali SH, Vlugt TJH, Lin L-C (2017) Atomistic understanding of zeolite nanosheets for
water desalination. J Phys Chem C 121:11273–11280
6. Dulebohn J, Ahmadiannamini P, Wang T, Kim S-S, Pinnavaia TJ, Tarabara VV (2014) Polymer
mesocomposites: ultrafiltration membrane materials with enhanced permeability, selectivity
and fouling resistance. J Membr Sci 453:478–488
7. Dong H, Zhao L, Zhang L, Chen H, Gao C, Ho WSW (2015) High-flux reverse osmosis
membranes incorporated with NaY zeolite nanoparticles for brackish water desalination. J
Membr Sci 476:373–383
8. Mouterde T, Keerthi A, Poggioli AR, Dar SA, Siria A, Geim AK, Bocquet L, Radha B (2019)
Molecular streaming and its voltage control in angstrom-scale channels. Nature 567:87–90
9. Bertolazzi S, Brivio J, Kis A (2011) Stretching and breaking of ultrathin MoS 2 . ACS Nano
5:9703–9709