of modern technologies along with increase in their efficiency. The science and
technology involved in desalination process is undergoing revolution involving the
use of nanotechnology with the development of novel nanoporous membranes. The
nanoporous membranes hold the key to solve the drawbacks of the conventional
techniques. In contrast with classical RO membranes, where water gets transported
slowly through a solution–diffusion process, nanoporous membranes can allow fast
convective water flow across well-defined channels. Due to its small dimensions,
nanoporous membranes are used as filters working on the basis of molecular size
separation; small molecules can pass through them, while larger ones cannot. These
pores can also make use of other physical principles, such as charge, hydrophobicity
to reject ions, or other molecular solutes. This method is characterized as one of the
membrane separation techniques that uses an effective separation membrane crafted
by creating nanoscale pores in different materials like zeolites, carbon, and silica
(Sint et al. 2008; Surwade et al. 2015). The materials used as nanoporous membranes
must be chemically and mechanically stable and flexible with thickness ranging in
atomic scale (Cohen-Tanugi et al. 2014; Mishra and Ramaprabhu 2011; Sint et al.
2008; Surwade et al. 2015) Theoretical studies show that the performance of such
membranes would be superior to state-of-the-art polymer-based filtration membranes, and experimental studies have recently been conducted to explore their
potential (Surwade et al. 2015). This review aims to bring out the potential of
nanoporous membrane as efficient separation membranes in desalination.
4.2 Evolution of Desalinating Techniques
Several desalinating methods have been designed and experimented for treating
seawater to overcome the water shortage. Most widely, commercially proven desalination technologies fall into two categories, thermal- (evaporative) and membranebased methods. Membrane methods are less energy intensive than thermal methods,
and since energy consumption directly affects the cost-effectiveness, the feasibility
of using membrane-based methods for desalination technologies has attracted great
attention (Fig. 4.1).
4.2.1 Multi-effect Distillation
The multi-effect distillation (MED) process is the oldest technique for seawater
desalination that involves consecutive evaporation and condensation (Ophir and
Lokiec 2005). The first report on MED dates back to the middle of the nineteenth
century (Van der Bruggen and Vandecasteele 2002). The process is carried out
through a series of evaporators called effects that works on the principle of
4 Functional Properties of Nanoporous Membranes for the Desalination of Water
133
technology involved in desalination process is undergoing revolution involving the
use of nanotechnology with the development of novel nanoporous membranes. The
nanoporous membranes hold the key to solve the drawbacks of the conventional
techniques. In contrast with classical RO membranes, where water gets transported
slowly through a solution–diffusion process, nanoporous membranes can allow fast
convective water flow across well-defined channels. Due to its small dimensions,
nanoporous membranes are used as filters working on the basis of molecular size
separation; small molecules can pass through them, while larger ones cannot. These
pores can also make use of other physical principles, such as charge, hydrophobicity
to reject ions, or other molecular solutes. This method is characterized as one of the
membrane separation techniques that uses an effective separation membrane crafted
by creating nanoscale pores in different materials like zeolites, carbon, and silica
(Sint et al. 2008; Surwade et al. 2015). The materials used as nanoporous membranes
must be chemically and mechanically stable and flexible with thickness ranging in
atomic scale (Cohen-Tanugi et al. 2014; Mishra and Ramaprabhu 2011; Sint et al.
2008; Surwade et al. 2015) Theoretical studies show that the performance of such
membranes would be superior to state-of-the-art polymer-based filtration membranes, and experimental studies have recently been conducted to explore their
potential (Surwade et al. 2015). This review aims to bring out the potential of
nanoporous membrane as efficient separation membranes in desalination.
4.2 Evolution of Desalinating Techniques
Several desalinating methods have been designed and experimented for treating
seawater to overcome the water shortage. Most widely, commercially proven desalination technologies fall into two categories, thermal- (evaporative) and membranebased methods. Membrane methods are less energy intensive than thermal methods,
and since energy consumption directly affects the cost-effectiveness, the feasibility
of using membrane-based methods for desalination technologies has attracted great
attention (Fig. 4.1).
4.2.1 Multi-effect Distillation
The multi-effect distillation (MED) process is the oldest technique for seawater
desalination that involves consecutive evaporation and condensation (Ophir and
Lokiec 2005). The first report on MED dates back to the middle of the nineteenth
century (Van der Bruggen and Vandecasteele 2002). The process is carried out
through a series of evaporators called effects that works on the principle of
4 Functional Properties of Nanoporous Membranes for the Desalination of Water
133