water flux. However, employing this technique limited the range of functional
groups that could be attached to the pores. Muller et al. reported that amino
functionalization of PVDF microfiltration membranes by direct plasma treatment
and plasma pulse technique resulted in modified membranes with improved properties (Müller and Oehr 1999).
4.6.3 Graft Polymerization
Functional groups present on the pore surface are excited upon irradiation of light
resulting in the generation of reactive radicals that initiate the grafting process. On
using photosensitizer in photochemical grafting, free radicals that generated abstract
hydrogen atoms from the base polymer (membrane) form a functionalized pore.
Research works state that amino functionalization of PVDF microfiltration membranes by grafting technique was more efficient than plasma modification (Müller
and Oehr 1999). Currently grafting technique is being extensively employed in
copolymer templating as a functionalization step.
4.6.4 Copolymer Templating
Copolymer templating is one of the most advanced techniques for the synthesis of
porous membranes. This technique aids in producing a membrane with uniformly
distributed pores of required pore diameter. In addition, this technique also aids in
functionalizing the pores. Polymer blocks with patterns containing provision to
functionalize the pore region as a result of their ability to self-assemble into microdomains are developed. Further manipulation of these patterns with chemical or
physical treatment aids in effective functionalization. Research works have shown
that polyethylene oxide (PEO)-functionalized CdSe nanorods were successfully
used to functionalize the membrane by assembling the nanorods into the channels
and pores of diblock copolymer templates (Zhang et al. 2006). Ryan et al. reported
the synthesis of functionalized membrane of PDMA triblock polymer by RAFT
(reversible addition–fragmentation chain transfer) polymerization. This membrane
was functionalized by converting the PDMA molecules lining the pore into PAA by
hydrolysis which enhanced the solute rejection ratio (Mulvenna et al. 2014).
4.7 Process Parameters in Desalination System
Desalination of water through nanopores depends on the physical properties of
nanoporous membrane, type of ions in contact with the water molecules, and other
process parameters such as pressure, temperature, and water flux. The selective
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J. Ganesan et al.
groups that could be attached to the pores. Muller et al. reported that amino
functionalization of PVDF microfiltration membranes by direct plasma treatment
and plasma pulse technique resulted in modified membranes with improved properties (Müller and Oehr 1999).
4.6.3 Graft Polymerization
Functional groups present on the pore surface are excited upon irradiation of light
resulting in the generation of reactive radicals that initiate the grafting process. On
using photosensitizer in photochemical grafting, free radicals that generated abstract
hydrogen atoms from the base polymer (membrane) form a functionalized pore.
Research works state that amino functionalization of PVDF microfiltration membranes by grafting technique was more efficient than plasma modification (Müller
and Oehr 1999). Currently grafting technique is being extensively employed in
copolymer templating as a functionalization step.
4.6.4 Copolymer Templating
Copolymer templating is one of the most advanced techniques for the synthesis of
porous membranes. This technique aids in producing a membrane with uniformly
distributed pores of required pore diameter. In addition, this technique also aids in
functionalizing the pores. Polymer blocks with patterns containing provision to
functionalize the pore region as a result of their ability to self-assemble into microdomains are developed. Further manipulation of these patterns with chemical or
physical treatment aids in effective functionalization. Research works have shown
that polyethylene oxide (PEO)-functionalized CdSe nanorods were successfully
used to functionalize the membrane by assembling the nanorods into the channels
and pores of diblock copolymer templates (Zhang et al. 2006). Ryan et al. reported
the synthesis of functionalized membrane of PDMA triblock polymer by RAFT
(reversible addition–fragmentation chain transfer) polymerization. This membrane
was functionalized by converting the PDMA molecules lining the pore into PAA by
hydrolysis which enhanced the solute rejection ratio (Mulvenna et al. 2014).
4.7 Process Parameters in Desalination System
Desalination of water through nanopores depends on the physical properties of
nanoporous membrane, type of ions in contact with the water molecules, and other
process parameters such as pressure, temperature, and water flux. The selective
146
J. Ganesan et al.