317
solution above pH 9.24. Electrostatic attractions were the key factor for the adsorption of boron on Na-montmorillonite surface (Keren et al. 1981). Boron adsorption
on montmorillonite, illite, and kaolinite clays was investigated by Keren et al.
(1981). Calcium (Ca) forms of the clays were used for the adsorption of boron.
Maximum boron adsorption was achieved in alkaline conditions since the affinity of
the clays for B(OH) 4
−
was much higher than B(OH) 3 . Adsorption capacities were
achieved as 2.94, 11.8, and 15.1 μmole g
−1
for Ca-kaolinite, Ca-montmorillonite,
and Ca-illite, respectively (Keren and Mezuman 1981).
Organic components were also used for the modification of the clay surface.
Nonylammonium chloride was used to modify bentonite, sepiolite, and illite clays
for boron adsorption. Hydrophilic surface was changed to hydrophobic form with
the modification nonylammonium chloride. Freundlich and Dubinin-Radushkevich
isotherm models were fitted the experimental data for boron adsorption. Modification
of bentonite and illite with nonylammonium chloride increased the boron adsorption. It was concluded that the low-cost bentonite, which showed the highest adsorption capacity, could be used for industrial applications (Karahan et al. 2006).
Reinert et al. (2011) studied the boron removal using allophone, which is a natural mineral. Initial boron concentrations were between 1 and 100 mg L
−1
. Natural
clay mineral with aluminosilicate content was modified with N-methyl-D-glucamine
structure, which is a boron-specific complex. As a result, 80% boron removal was
obtained using modified allophone (Reinert et al. 2011).
12.5.2 Industrial Waste
Öztürk and Kavak (2005) used fly ash as adsorbent for removal of boron. There are
metal oxides in fly ash structure. In the acidic medium, metal oxides are positively
charged as they form complexes, and as a result, negatively charged borate ions
were adsorbed to the fly ash surface by electrostatic interaction. Boron solution with
initial concentration of 600 mg L
−1
and fly ash as combustion process waste were
used as adsorbent, and boron removal reached up to 90% from the solution (Öztürk
and Kavak 2005).
Boron removal by using aluminum production process waste neutralized red
sludge was studied by Çengeloğlu et al. (2007). Initial boron concentration was
used between 2 and 1200 mg L
−1
, and as a result of batch system studies, up to 90%
boron removal was achieved. Since the neutral surface charge of neutralized red
sludge is around pH 8 and is negatively charged at this pH value, the maximum
adsorption was below pH 8 (Çengeloğlu et al. 2007).
Aluminum-based water treatment residuals include Al 2 O 3 , Fe 2 O 3 , and SiO 2 in its
structure. It was used for removal of boron. van der Waals forces and electrostatic
interactions were the major forces at different pH levels for boron removal. The
maximum boron adsorption capacity was found as 0.98 mg g
−1
at pH 8.3 (Irawan
et al. 2011).
12 Application of Adsorption Methods for Boron Uptake
solution above pH 9.24. Electrostatic attractions were the key factor for the adsorption of boron on Na-montmorillonite surface (Keren et al. 1981). Boron adsorption
on montmorillonite, illite, and kaolinite clays was investigated by Keren et al.
(1981). Calcium (Ca) forms of the clays were used for the adsorption of boron.
Maximum boron adsorption was achieved in alkaline conditions since the affinity of
the clays for B(OH) 4
−
was much higher than B(OH) 3 . Adsorption capacities were
achieved as 2.94, 11.8, and 15.1 μmole g
−1
for Ca-kaolinite, Ca-montmorillonite,
and Ca-illite, respectively (Keren and Mezuman 1981).
Organic components were also used for the modification of the clay surface.
Nonylammonium chloride was used to modify bentonite, sepiolite, and illite clays
for boron adsorption. Hydrophilic surface was changed to hydrophobic form with
the modification nonylammonium chloride. Freundlich and Dubinin-Radushkevich
isotherm models were fitted the experimental data for boron adsorption. Modification
of bentonite and illite with nonylammonium chloride increased the boron adsorption. It was concluded that the low-cost bentonite, which showed the highest adsorption capacity, could be used for industrial applications (Karahan et al. 2006).
Reinert et al. (2011) studied the boron removal using allophone, which is a natural mineral. Initial boron concentrations were between 1 and 100 mg L
−1
. Natural
clay mineral with aluminosilicate content was modified with N-methyl-D-glucamine
structure, which is a boron-specific complex. As a result, 80% boron removal was
obtained using modified allophone (Reinert et al. 2011).
12.5.2 Industrial Waste
Öztürk and Kavak (2005) used fly ash as adsorbent for removal of boron. There are
metal oxides in fly ash structure. In the acidic medium, metal oxides are positively
charged as they form complexes, and as a result, negatively charged borate ions
were adsorbed to the fly ash surface by electrostatic interaction. Boron solution with
initial concentration of 600 mg L
−1
and fly ash as combustion process waste were
used as adsorbent, and boron removal reached up to 90% from the solution (Öztürk
and Kavak 2005).
Boron removal by using aluminum production process waste neutralized red
sludge was studied by Çengeloğlu et al. (2007). Initial boron concentration was
used between 2 and 1200 mg L
−1
, and as a result of batch system studies, up to 90%
boron removal was achieved. Since the neutral surface charge of neutralized red
sludge is around pH 8 and is negatively charged at this pH value, the maximum
adsorption was below pH 8 (Çengeloğlu et al. 2007).
Aluminum-based water treatment residuals include Al 2 O 3 , Fe 2 O 3 , and SiO 2 in its
structure. It was used for removal of boron. van der Waals forces and electrostatic
interactions were the major forces at different pH levels for boron removal. The
maximum boron adsorption capacity was found as 0.98 mg g
−1
at pH 8.3 (Irawan
et al. 2011).
12 Application of Adsorption Methods for Boron Uptake