Microfibrous palygorskite clay was mixed to a precursor nanocrystalline TiO 2 sol
containing Triton X-100 nonionic surfactant, and the resulting mixture was spread
on a glass slides by dip-coating (Stathatos et al. 2012). A subsequent thermal
treatment at 500
C was applied to remove organic component. Highly nanostructured porous palygorskite/TiO 2 composite films with variable quantities of
palygorskite were produced and tested as catalysts for the photodecomposition of
basic blue azo dye in water under UV light irradiation. The film with an optimal
palygorskite/TiO 2 weight ratio of 3/2 was found the most effective photocatalyst. It
was observed that palygorskite has a low photocatalytic activity under UV illumination probably due to the presence of light-activated oxides such as Fe 2 O 3 and TiO 2
present in the clay, and it is assumed that the coexistence of MgO and CaO helps to a
better hydroxylation of the surface or to slower charge recombination. The
photocatalytic activities of the composites are due to a synergetic effect of the
palygorskite clay and anatase nanoparticles. The reusability of the palygorskite/
TiO 2 composite films have been evidenced for four cycles. An interesting approach
is the immobilization of TiO 2 nanoparticles on macroporous alumina (or clay) disk
(or tubular) membranes for filtration. Titania and titania-silica sols were deposited on
macroporous alumina disk membranes (Tajer-Kajinebaf et al. 2014). To get anatase
with the most favorable crystallite size of 10 nm, a thermal treatment at 400
C was
optimal for both TiO 2 -alumina and TiO 2 /SiO 2 -alumina membranes. The membrane
composites have been successfully used for removing methyl orange from aqueous
solution by coupling membrane separation process with photocatalytic technique.
Since the presence of silica delays the phase transformation of anatase to rutile and
inhibits grain growth of anatase, the TiO 2 /SiO 2 -alumina membranes were assumed
to have great potential for efficient water treatment. TiO 2 nanoparticles have been
also incorporated polysulfone (PSf) ultrafiltration membrane for a selective degradation of methylene blue (Melvin Ng et al. 2017). First, commercial P25 TiO 2
nanoparticles were modified and molecularly imprinting with methylene blue as
template in a polymer matrix. The imprinted TiO 2 was then introduced in the
precursor mixture of the PSf membrane. The photocatalytic and selective properties
of TiO 2 entrapped in PSf membrane were successfully evidenced in an integrated
photodegradation-ultrafiltration system. The incorporation of photoactive TiO 2
nanoparticles onto textile fibers has been studied for self-cleaning (Wang et al.
2015a, b). It is an interesting approach for water treatment since TiO 2 -supported
onto textile can facilitate the photocatalyst recovery from reaction medium. The use
of textile such as sackcloth for TiO 2 photocatalyst support offers the opportunity to
produce a composite highly active to photodegrade acid black 26, a dye used in the
textile, and stable for applications in water treatment (Vaez et al. 2012). Embedding
of titania nanoparticles into porous cellulose aerogel is also attractive for water
treatment since the composite is like a textile felt that can be easily handled and
used for filtration (Jiao et al. 2015). The obtained anatase TiO 2 /cellulose aerogel
showed a high photocatalytic activity for indigo carmine dye degradation in aqueous
solution under UV light and maintained the well-define shape throughout the
radiation process. Another interesting shaping is the production of TiO 2 nanofibers
by electrospinning that can be used as reactive filtration materials for water treatment
applications (Nalbandian et al. 2015).
64
B. Lebeau et al.
containing Triton X-100 nonionic surfactant, and the resulting mixture was spread
on a glass slides by dip-coating (Stathatos et al. 2012). A subsequent thermal
treatment at 500
C was applied to remove organic component. Highly nanostructured porous palygorskite/TiO 2 composite films with variable quantities of
palygorskite were produced and tested as catalysts for the photodecomposition of
basic blue azo dye in water under UV light irradiation. The film with an optimal
palygorskite/TiO 2 weight ratio of 3/2 was found the most effective photocatalyst. It
was observed that palygorskite has a low photocatalytic activity under UV illumination probably due to the presence of light-activated oxides such as Fe 2 O 3 and TiO 2
present in the clay, and it is assumed that the coexistence of MgO and CaO helps to a
better hydroxylation of the surface or to slower charge recombination. The
photocatalytic activities of the composites are due to a synergetic effect of the
palygorskite clay and anatase nanoparticles. The reusability of the palygorskite/
TiO 2 composite films have been evidenced for four cycles. An interesting approach
is the immobilization of TiO 2 nanoparticles on macroporous alumina (or clay) disk
(or tubular) membranes for filtration. Titania and titania-silica sols were deposited on
macroporous alumina disk membranes (Tajer-Kajinebaf et al. 2014). To get anatase
with the most favorable crystallite size of 10 nm, a thermal treatment at 400
C was
optimal for both TiO 2 -alumina and TiO 2 /SiO 2 -alumina membranes. The membrane
composites have been successfully used for removing methyl orange from aqueous
solution by coupling membrane separation process with photocatalytic technique.
Since the presence of silica delays the phase transformation of anatase to rutile and
inhibits grain growth of anatase, the TiO 2 /SiO 2 -alumina membranes were assumed
to have great potential for efficient water treatment. TiO 2 nanoparticles have been
also incorporated polysulfone (PSf) ultrafiltration membrane for a selective degradation of methylene blue (Melvin Ng et al. 2017). First, commercial P25 TiO 2
nanoparticles were modified and molecularly imprinting with methylene blue as
template in a polymer matrix. The imprinted TiO 2 was then introduced in the
precursor mixture of the PSf membrane. The photocatalytic and selective properties
of TiO 2 entrapped in PSf membrane were successfully evidenced in an integrated
photodegradation-ultrafiltration system. The incorporation of photoactive TiO 2
nanoparticles onto textile fibers has been studied for self-cleaning (Wang et al.
2015a, b). It is an interesting approach for water treatment since TiO 2 -supported
onto textile can facilitate the photocatalyst recovery from reaction medium. The use
of textile such as sackcloth for TiO 2 photocatalyst support offers the opportunity to
produce a composite highly active to photodegrade acid black 26, a dye used in the
textile, and stable for applications in water treatment (Vaez et al. 2012). Embedding
of titania nanoparticles into porous cellulose aerogel is also attractive for water
treatment since the composite is like a textile felt that can be easily handled and
used for filtration (Jiao et al. 2015). The obtained anatase TiO 2 /cellulose aerogel
showed a high photocatalytic activity for indigo carmine dye degradation in aqueous
solution under UV light and maintained the well-define shape throughout the
radiation process. Another interesting shaping is the production of TiO 2 nanofibers
by electrospinning that can be used as reactive filtration materials for water treatment
applications (Nalbandian et al. 2015).
64
B. Lebeau et al.