ions on synthesized mesoporous silica from sodium silicate. The prepared catalysts
were characterized for their textural and surface morphology. High concentration of
soluble metal precursor with 8.0 wt% Fe
3+ can be easily deposited on silica. The
results showed that the Fe–SiO 2 catalyst demonstrated good performance in the
degradation of 50 ppm Acid Blue 29 (AB29) which was nearly completed in
100 min under visible light irradiation with optimum operating conditions at 0.4 g
Fe–SiO 2 /L, pH 3.0, and 10 mM H 2 O 2 . The catalyst is reusable over four consecutive
cycles and minimal leaching of iron ions (<0.5 ppm) was observed.
A sewage sludge-derived porous carbon (SC), which was prepared by physicochemical activation and carbonization (600
C), was applied for the adsorption and
degradation of 1-diazo-2-naphthol-4-sulfonic acid (1, 2, 4-acid) in the presence of
H 2 O 2 and the performance was compared to that of pure Fe 3 O 4 magnetic
nanoparticles (MNPs). The prepared SC showed mesoporous structure with magnetic property, which made it favorable for solid–liquid separation application.
Further experiments revealed that SC had a higher adsorption capacity and degradation efficiency of 1, 2, 4-acid than bare Fe 3 O 4 . The Langmuir and Freundlich
model fitted the isotherm data and illustrated that the equilibrium adsorption amount
of 1, 2, 4-acid onto SC (95.1 mg g
À1 ) was quadruple as large as that on Fe 3 O 4
(26.4 mg g
À1 ). The subsequent degradation experiments were conducted at pH ¼ 5.0
in the presence of 15 mM H 2 O 2 with regard to 1, 2, 4-acid degradation efficiency and
metal ions leach. The 120 min treatment in SC/H 2 O 2 system achieved 94% of 1, 2,
4-acid (from 150 mg L
À1 after adsorption equilibrium to 9 mg L
À1 ) and 48.1% TOC
reduction, far higher than the efficiency of 46% and 24.3% by using Fe 3 O 4 MNPs.
Further analysis evidenced the cocatalytic effect of iron, carbon, silicon, and aluminum, which existed in large quantities in sludge-derived SC. The carbonaceous
phase along with silica contributes to an increase in the dispersion of catalytic
centers and an adsorbent to concentrate organic pollutant, whereas the iron oxide
as well as alumina provides the catalytic centers for a Haber–Weiss initiated
reactions [20].
11.2.5 Graphene
A facile Stöber-like method was used to prepare the ultra-dispersed Fe 3 O 4
nanoparticles (3–8 nm) on the reduced graphene oxide (RGO) sheet by using (Fe
(acac) 3 ) as the iron precursor. This strategy provides a facile and environmentally
friendly method for the large-scale synthesis of Fe 3 O 4 /RGO without any additional
reductants and organic surfactants. The prepared hybrid materials were used as the
photo-Fenton catalyst, which displayed a high and stable performance for the
recyclable degradation of methyl orange pollutant, owing to the high conversion
efficiency of Fe
3+ /Fe
2+ and the magnetic property of Fe 3 O 4 [21]. Three-dimensional
(3D) graphene aerogel (3D-GA)-supported Fe 2 O 3 nanocrystals were prepared
through a Stöber-like method [22]. Fe 2 O 3 /GAs have a 3D network structure with a
high surface area of 316 m
2 g
À1 and physicochemical stability. 3D-GAs can inhibit
11.2 Heterogeneous Photo-Fenton Reaction
265
were characterized for their textural and surface morphology. High concentration of
soluble metal precursor with 8.0 wt% Fe
3+ can be easily deposited on silica. The
results showed that the Fe–SiO 2 catalyst demonstrated good performance in the
degradation of 50 ppm Acid Blue 29 (AB29) which was nearly completed in
100 min under visible light irradiation with optimum operating conditions at 0.4 g
Fe–SiO 2 /L, pH 3.0, and 10 mM H 2 O 2 . The catalyst is reusable over four consecutive
cycles and minimal leaching of iron ions (<0.5 ppm) was observed.
A sewage sludge-derived porous carbon (SC), which was prepared by physicochemical activation and carbonization (600
C), was applied for the adsorption and
degradation of 1-diazo-2-naphthol-4-sulfonic acid (1, 2, 4-acid) in the presence of
H 2 O 2 and the performance was compared to that of pure Fe 3 O 4 magnetic
nanoparticles (MNPs). The prepared SC showed mesoporous structure with magnetic property, which made it favorable for solid–liquid separation application.
Further experiments revealed that SC had a higher adsorption capacity and degradation efficiency of 1, 2, 4-acid than bare Fe 3 O 4 . The Langmuir and Freundlich
model fitted the isotherm data and illustrated that the equilibrium adsorption amount
of 1, 2, 4-acid onto SC (95.1 mg g
À1 ) was quadruple as large as that on Fe 3 O 4
(26.4 mg g
À1 ). The subsequent degradation experiments were conducted at pH ¼ 5.0
in the presence of 15 mM H 2 O 2 with regard to 1, 2, 4-acid degradation efficiency and
metal ions leach. The 120 min treatment in SC/H 2 O 2 system achieved 94% of 1, 2,
4-acid (from 150 mg L
À1 after adsorption equilibrium to 9 mg L
À1 ) and 48.1% TOC
reduction, far higher than the efficiency of 46% and 24.3% by using Fe 3 O 4 MNPs.
Further analysis evidenced the cocatalytic effect of iron, carbon, silicon, and aluminum, which existed in large quantities in sludge-derived SC. The carbonaceous
phase along with silica contributes to an increase in the dispersion of catalytic
centers and an adsorbent to concentrate organic pollutant, whereas the iron oxide
as well as alumina provides the catalytic centers for a Haber–Weiss initiated
reactions [20].
11.2.5 Graphene
A facile Stöber-like method was used to prepare the ultra-dispersed Fe 3 O 4
nanoparticles (3–8 nm) on the reduced graphene oxide (RGO) sheet by using (Fe
(acac) 3 ) as the iron precursor. This strategy provides a facile and environmentally
friendly method for the large-scale synthesis of Fe 3 O 4 /RGO without any additional
reductants and organic surfactants. The prepared hybrid materials were used as the
photo-Fenton catalyst, which displayed a high and stable performance for the
recyclable degradation of methyl orange pollutant, owing to the high conversion
efficiency of Fe
3+ /Fe
2+ and the magnetic property of Fe 3 O 4 [21]. Three-dimensional
(3D) graphene aerogel (3D-GA)-supported Fe 2 O 3 nanocrystals were prepared
through a Stöber-like method [22]. Fe 2 O 3 /GAs have a 3D network structure with a
high surface area of 316 m
2 g
À1 and physicochemical stability. 3D-GAs can inhibit
11.2 Heterogeneous Photo-Fenton Reaction
265