montmorillonite heterogeneous ion catalyst synthesized by precipitation method was
also used for the removal of rhodamine B and methylene blue.
Vermiculite is an economical and commonly available clay mineral which consists of a sandwich arrangement of octahedral alumina or magnesia in the middle of
two tetrahedral silicate sheets (Chen et al. 2010). Due to its layered structure and iron
species being covalently bound to these clay layers, the leaching of iron species will
be minimum (Barabaszová and Valášková 2013; Purceno et al. 2012). Iron-pillared
vermiculite prepared by replacing the interlayer cations of the clay with iron ions in
the interlayer spaces and free iron ions on its surface effectively decolorized azo dye
reactive brilliant orange X-GN (Chen et al. 2010). The heterogeneous photo-Fenton
catalyst enhanced the color removal by producing more hydroxyl radicals to attack
the chromophoric group of pollutant and have shown longer stability resulting in
more than 90% decolorization for three successive reuses studies. In another study, a
heterogeneous Fenton catalyst montmorillonite K10 containing ferric oxide was
used by Daud et al. (2010) for the discolorization of acid red 1, and the effects of
different parameters affecting was studied. They have observed that the decolorization of dye occurs due to the catalytic reaction between the ferric ions and hydrogen
peroxide and observed a maximum removal of 99% at 0.14 wt.% ironmontmorillonite K10, 5.0 g L
À1 catalyst dosage, and 16 mM of H 2 O 2 at
50 mg L
À1 initial acid red dye concentration.
Kaolinite is a layered clay mineral consisting of one tetrahedral sheet connected
through an oxygen atom with a central alumina octahedral sheet. They are rich in
oxides of aluminium and silica created from the chemical weathering of rocks in the
hot and wet atmosphere (Ayodele 2013). Ayodele (2013) observed that phosphoric
acid treatment on kaolinite clay gave a satisfactory and suitable anchoring of iron
metals because of the introduction of a monolayer of phosphate functional groups on
the surface of the catalyst. In another study, Ayodele and Hameed (2013) reported
that incorporating iron ions on phosphoric acid-treated kaolinite clay resulted in a
larger surface area to produce sufficient hydroxyl radicals during the photo-Fenton
degradation of nitrophenol. The formation of monolayer phosphate functional
groups increased the negatively charged active sites on the catalysts and resulted
in degradation of nitrophenol without pH adjustments. Apart from this, Guo et al.
(2014) synthesized a Fe 2 O 3 –kaolin heterogeneous catalyst for the degradation of
rhodamine B through photo-Fenton under visible light irradiation. The possible
degradation mechanism occurred by the cyclic formation of ferric/ferrous ions in
the system where the ferric ions get photoreduced to ferrous on the catalyst surface
and to generate hydroxyl radicals while reacting with hydrogen peroxide and get
oxidized into ferric ion .
Sepiolite is a microfibrous clay mineral with its basic structural units consisting of
silicon–oxygen tetrahedra and magnesium–oxygen octahedra bonds (Gao et al.
2013). These clay minerals possess a high adsorbing capacity and larger surface
area, due to the block and tunnel structure of the mineral, which could reduce the
leaching of iron ions during the degradation reaction (Su et al. 2016). A heterogeneous catalyst poly-hydroxyl-iron/sepiolite fabricated through an impregnation
method was used for the visible light irradiated photo-Fenton-like removal of
528
A. V. Karim et al.
also used for the removal of rhodamine B and methylene blue.
Vermiculite is an economical and commonly available clay mineral which consists of a sandwich arrangement of octahedral alumina or magnesia in the middle of
two tetrahedral silicate sheets (Chen et al. 2010). Due to its layered structure and iron
species being covalently bound to these clay layers, the leaching of iron species will
be minimum (Barabaszová and Valášková 2013; Purceno et al. 2012). Iron-pillared
vermiculite prepared by replacing the interlayer cations of the clay with iron ions in
the interlayer spaces and free iron ions on its surface effectively decolorized azo dye
reactive brilliant orange X-GN (Chen et al. 2010). The heterogeneous photo-Fenton
catalyst enhanced the color removal by producing more hydroxyl radicals to attack
the chromophoric group of pollutant and have shown longer stability resulting in
more than 90% decolorization for three successive reuses studies. In another study, a
heterogeneous Fenton catalyst montmorillonite K10 containing ferric oxide was
used by Daud et al. (2010) for the discolorization of acid red 1, and the effects of
different parameters affecting was studied. They have observed that the decolorization of dye occurs due to the catalytic reaction between the ferric ions and hydrogen
peroxide and observed a maximum removal of 99% at 0.14 wt.% ironmontmorillonite K10, 5.0 g L
À1 catalyst dosage, and 16 mM of H 2 O 2 at
50 mg L
À1 initial acid red dye concentration.
Kaolinite is a layered clay mineral consisting of one tetrahedral sheet connected
through an oxygen atom with a central alumina octahedral sheet. They are rich in
oxides of aluminium and silica created from the chemical weathering of rocks in the
hot and wet atmosphere (Ayodele 2013). Ayodele (2013) observed that phosphoric
acid treatment on kaolinite clay gave a satisfactory and suitable anchoring of iron
metals because of the introduction of a monolayer of phosphate functional groups on
the surface of the catalyst. In another study, Ayodele and Hameed (2013) reported
that incorporating iron ions on phosphoric acid-treated kaolinite clay resulted in a
larger surface area to produce sufficient hydroxyl radicals during the photo-Fenton
degradation of nitrophenol. The formation of monolayer phosphate functional
groups increased the negatively charged active sites on the catalysts and resulted
in degradation of nitrophenol without pH adjustments. Apart from this, Guo et al.
(2014) synthesized a Fe 2 O 3 –kaolin heterogeneous catalyst for the degradation of
rhodamine B through photo-Fenton under visible light irradiation. The possible
degradation mechanism occurred by the cyclic formation of ferric/ferrous ions in
the system where the ferric ions get photoreduced to ferrous on the catalyst surface
and to generate hydroxyl radicals while reacting with hydrogen peroxide and get
oxidized into ferric ion .
Sepiolite is a microfibrous clay mineral with its basic structural units consisting of
silicon–oxygen tetrahedra and magnesium–oxygen octahedra bonds (Gao et al.
2013). These clay minerals possess a high adsorbing capacity and larger surface
area, due to the block and tunnel structure of the mineral, which could reduce the
leaching of iron ions during the degradation reaction (Su et al. 2016). A heterogeneous catalyst poly-hydroxyl-iron/sepiolite fabricated through an impregnation
method was used for the visible light irradiated photo-Fenton-like removal of
528
A. V. Karim et al.