radiation. A combination of carbon-based nanomaterials with TiO 2 nanoparticles is
promising heterogeneous photocatalyst, used for the degradation of many pollutant
in air and water. Rasheed et al. (2019) reviewed on the potential applications of TiO 2
and SiO 2 functionalized CNTs as catalyst to remove or degrade various type of
pollutants, including synthetic dyes or dye-based hazardous waste effluents, as
polycyclic aromatic hydrocarbons (PAHs), pharmaceutically active compounds,
pesticides, toxic heavy elements, remediation of metal-contaminated soil, and miscellaneous organic contaminants. The functionalization of TiO 2 /SiO 2 on carbon
nanotubes is the best example of heterogeneous photocatalysis in the oxidation
process.
Xu et al. (2010) reported wet impregnation method for the preparation of
photoreactive TiO 2 /MWCNT nanocomposite materials. The as-prepared TiO 2 /
MWCNT nanocomposite, for the first time, is used for gas-phase degradation of
benzene. It is found that the TiO 2 / MWCNT nanocomposite shows an enhanced
photocatalytic activity toward benzene degradation, as compared to commercial
TiO 2 (P25, Degussa). In the concern of use of CNT-TiO 2 composite, Wongaree
et al. (2016) prepared CNT/TiO 2 nanofibers by electrospinning CNT/poly(vinyl
pyrrolidone) (PVP) solution followed by the removal of PVP by calcination at
450
C. CNT/TiO 2 nanofibers were studied for degradation of gaseous benzene
under visible light irradiation. The photodegradation of gaseous benzene by
50wtCNT/TiO 2 nanofibers with 14 filters in a simulated air purifier system under
visible light irradiation was 52% within 90 min. CNT exhibited a synergistic effect
on the enhancement of photocatalytic activity for CNT/TiO 2 nanofibers by increasing specific surface area, reducing band gap energy, and reducing electron
recombination.
Bai et al. (2017) synthesized a series of TiO 2 -graphene composites (P25-GR)
with different GR weight ratios by hydrothermal reaction between graphene oxide
(GO) and P25. P25-GR composites as a photocatalyst used for removal of phenanthrene (PHE), fluoranthene (FLAN), and benzo[a]pyrene (BaP). The results showed
that P25–2.5%GR exhibited enhancement in both adsorption and photodegradation,
and almost 80% of PAHs were removed after 2 h photocatalysis.
Fu et al. prepared a novel GOTiO 2 -Sr(OH) 2 /SrCO 3 nanocomposite and evaluated
its solar-light photocatalytic activity for degradation of PAH (phenanthrene) in
aqueous solution. Results showed that the presence of 50 mg/L of the photocatalyst
enhanced the pseudo-first-order photodegradation rate constant of phenanthrene by
11.6 times from 0.0005 Æ 0.0000 min
À1 (control) to 0.0058 Æ 0.0004 min
À1 . This
photodegradation was attributed to the hybridization between the coupling of TiO 2
with Sr(OH) 2 /SrCO 3 and the electron transport in graphene oxide sheets. In the
presence of GOTiO 2 -Sr(OH) 2 /SrCO 3 , the degradation rate constant was 12.8 times
than without GO-TiO 2 Sr(OH) 2 /SrCO 3 . The results of the study suggest that
GO-TiO 2 -Sr(OH) 2 /SrCO 3 can be considered as a highly effective and robust
photocatalyst for energy-effective photodegradation of PAHs in complex water
matrices.
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A. Singh et al.
promising heterogeneous photocatalyst, used for the degradation of many pollutant
in air and water. Rasheed et al. (2019) reviewed on the potential applications of TiO 2
and SiO 2 functionalized CNTs as catalyst to remove or degrade various type of
pollutants, including synthetic dyes or dye-based hazardous waste effluents, as
polycyclic aromatic hydrocarbons (PAHs), pharmaceutically active compounds,
pesticides, toxic heavy elements, remediation of metal-contaminated soil, and miscellaneous organic contaminants. The functionalization of TiO 2 /SiO 2 on carbon
nanotubes is the best example of heterogeneous photocatalysis in the oxidation
process.
Xu et al. (2010) reported wet impregnation method for the preparation of
photoreactive TiO 2 /MWCNT nanocomposite materials. The as-prepared TiO 2 /
MWCNT nanocomposite, for the first time, is used for gas-phase degradation of
benzene. It is found that the TiO 2 / MWCNT nanocomposite shows an enhanced
photocatalytic activity toward benzene degradation, as compared to commercial
TiO 2 (P25, Degussa). In the concern of use of CNT-TiO 2 composite, Wongaree
et al. (2016) prepared CNT/TiO 2 nanofibers by electrospinning CNT/poly(vinyl
pyrrolidone) (PVP) solution followed by the removal of PVP by calcination at
450
C. CNT/TiO 2 nanofibers were studied for degradation of gaseous benzene
under visible light irradiation. The photodegradation of gaseous benzene by
50wtCNT/TiO 2 nanofibers with 14 filters in a simulated air purifier system under
visible light irradiation was 52% within 90 min. CNT exhibited a synergistic effect
on the enhancement of photocatalytic activity for CNT/TiO 2 nanofibers by increasing specific surface area, reducing band gap energy, and reducing electron
recombination.
Bai et al. (2017) synthesized a series of TiO 2 -graphene composites (P25-GR)
with different GR weight ratios by hydrothermal reaction between graphene oxide
(GO) and P25. P25-GR composites as a photocatalyst used for removal of phenanthrene (PHE), fluoranthene (FLAN), and benzo[a]pyrene (BaP). The results showed
that P25–2.5%GR exhibited enhancement in both adsorption and photodegradation,
and almost 80% of PAHs were removed after 2 h photocatalysis.
Fu et al. prepared a novel GOTiO 2 -Sr(OH) 2 /SrCO 3 nanocomposite and evaluated
its solar-light photocatalytic activity for degradation of PAH (phenanthrene) in
aqueous solution. Results showed that the presence of 50 mg/L of the photocatalyst
enhanced the pseudo-first-order photodegradation rate constant of phenanthrene by
11.6 times from 0.0005 Æ 0.0000 min
À1 (control) to 0.0058 Æ 0.0004 min
À1 . This
photodegradation was attributed to the hybridization between the coupling of TiO 2
with Sr(OH) 2 /SrCO 3 and the electron transport in graphene oxide sheets. In the
presence of GOTiO 2 -Sr(OH) 2 /SrCO 3 , the degradation rate constant was 12.8 times
than without GO-TiO 2 Sr(OH) 2 /SrCO 3 . The results of the study suggest that
GO-TiO 2 -Sr(OH) 2 /SrCO 3 can be considered as a highly effective and robust
photocatalyst for energy-effective photodegradation of PAHs in complex water
matrices.
222
A. Singh et al.