technologies that have been developed over the years for this purpose under the
common phenomenon named “desalination”. In terms of materials used, metal
oxides have found some potential use in more than one desalination technologies.
This last aspect will be the subject matter of this section.
Membrane filtration is one of the highly used technologies involved in desalination. Lin et al. (2012) had fabricated cobalt oxide silica filtration membranes for
removal of salt from aqueous solution. The authors used three initial concentration of
salt solutions, representing three different contaminated sources – brine solution,
seawater and brackish water. It was observed that with increasing salt concentration,
the water flux decreased. Most importantly, higher than 99% salt rejection was
realized by using these membranes. In a similar approach, Elma et al. (2015) showed
that mesoporous membranes formed from cobalt oxide silica can reach even more
than 99.7% of salt rejection with significant water flux. This efficient result was
attributed to the combination of mesopores and structural integrity of the membranes
(Fig. 1.7).
Another popular technology of desalination that makes use of metal oxides is
capacitive desalination. In a typical work, Myint et al. (2014) utilized a number of
micro and nanostructured materials of ZnO, like microspheres, microsheets,
nanorods and nanoparticles, as grafts on activated carbon cloth to form electrodes
for capacitive desalination of brackish water. The use of microsheets of ZnO
produced a desalination efficiency of 22%, a desalination capacity of 8.5 mgg
À1
and a regeneration/salt removal efficiency of 19%. On the other hand, use of
nanorods of Zno demonstrated respective values of 22%, 8.5 mgg
À1 and 21%. In
another similar study, a composite electrode made of Zno and activated carbon
produced a charge efficiency of 80.5% and a desalination capacity of 9.4 mgg
À1
(Liu et al. 2015). It was further shown that TiO 2 supported on graphene aerogel,
with a loading TiO 2 of 60.4 wt%, can also be used as a highly efficient threedimensional electrode material for capacitive desalination of aqueous saline solution
Fig. 1.7 Silica network microstructure and porous texture of (a) pure silica, and cobalt oxide silica
of the (b) microporous and (c) mesoporous samples. (Reprinted from Elma et al. (2015), with
permission from Elsevier)
12
K. Dutta
common phenomenon named “desalination”. In terms of materials used, metal
oxides have found some potential use in more than one desalination technologies.
This last aspect will be the subject matter of this section.
Membrane filtration is one of the highly used technologies involved in desalination. Lin et al. (2012) had fabricated cobalt oxide silica filtration membranes for
removal of salt from aqueous solution. The authors used three initial concentration of
salt solutions, representing three different contaminated sources – brine solution,
seawater and brackish water. It was observed that with increasing salt concentration,
the water flux decreased. Most importantly, higher than 99% salt rejection was
realized by using these membranes. In a similar approach, Elma et al. (2015) showed
that mesoporous membranes formed from cobalt oxide silica can reach even more
than 99.7% of salt rejection with significant water flux. This efficient result was
attributed to the combination of mesopores and structural integrity of the membranes
(Fig. 1.7).
Another popular technology of desalination that makes use of metal oxides is
capacitive desalination. In a typical work, Myint et al. (2014) utilized a number of
micro and nanostructured materials of ZnO, like microspheres, microsheets,
nanorods and nanoparticles, as grafts on activated carbon cloth to form electrodes
for capacitive desalination of brackish water. The use of microsheets of ZnO
produced a desalination efficiency of 22%, a desalination capacity of 8.5 mgg
À1
and a regeneration/salt removal efficiency of 19%. On the other hand, use of
nanorods of Zno demonstrated respective values of 22%, 8.5 mgg
À1 and 21%. In
another similar study, a composite electrode made of Zno and activated carbon
produced a charge efficiency of 80.5% and a desalination capacity of 9.4 mgg
À1
(Liu et al. 2015). It was further shown that TiO 2 supported on graphene aerogel,
with a loading TiO 2 of 60.4 wt%, can also be used as a highly efficient threedimensional electrode material for capacitive desalination of aqueous saline solution
Fig. 1.7 Silica network microstructure and porous texture of (a) pure silica, and cobalt oxide silica
of the (b) microporous and (c) mesoporous samples. (Reprinted from Elma et al. (2015), with
permission from Elsevier)
12
K. Dutta