116
E. Emekdar and U. K. ¸
Sahin
of the silicate. Molecules can penetrate inner layers due to breaking the water in the
inner layer by cations, and it is called hydrophobic adsorption [36]. Van der Waals
or hydrophobic interaction can be seen with ammonium cation alkali chains and
adsorbed nonpolar molecules at gaps of the inner layer. When organic cations are
placed at inner layers, they enlarge layer gaps [37].
Secondary adsorption occurs with Van der Waals forces which are between
adsorbed organic molecules and aliphatic chains of changeable cations. That is why
the secondary adsorption between molecules that have a low polarity or nonpolar
molecules and the long-chained ammonium montmorillonite complexes increases
with the increment of the basal gaps and primary adsorbed organic ions amount [38].
At the experiments that are done with alkali ammonium ions that have different
alkali chain lengths which are used as a surface-active agent, it is seen that the longer
chained alkali ammonium ions (C18-C20) increase the distance between the silicate
layers more than the shorter chained alkali ammonium ions (C9-C10). Also, between
unary, binary, trilogy, and quart onium ions, quart alkali ammonium ions are the most
effective ions that increase one layer distance to another one best [39]. The reason
for this is quart ammonium ions make a strong bond with MMT. This force increases
with the increment of the displaced components of the ammonium cations [40].
The sum of equivalent mass number of changeable cations (meg) at 100 g of the
mineral is called the cation exchange capacity (CEC), and it is a significant parameter
to nominate the most suitable clay type for defined end-use [41].
Bentonite which has a general formula of Al 4 Si 8 O 20 (OH) 4 .nH 2 O is clay that
shows the strong colloidal property, has high plasticity, has a soft handle, and can be
easily shaped. Also, it is an important ion exchanger that swells when it gets into the
water, can be activated by acid, darkens the drilling muds, and has wide surface area
[42, 43]. Inside the bentonite, there are natural clay minerals such as kaolin and illite
and non-clay minerals such as gypsum, quartz, rutile, calcite, dolomite, and volcanic
ash. They are found in nature in many colors such as white, gray, green, yellow, and
pink [42].
The most distinguishing property of bentonites is holding water inside their structure as presented in Fig. 5. Taking water in its structure and widening its crystalline
structure is called swelling. Swelling is directly proportional to the type and amount
of cations between the 2:1 segments. At these segments, generally, there are Na
+ and
Ca
+2 cations, and while the Na
+ /Ca
+2 equimolar ratio increases, the swelling also
increases [44].
The bentonite which can swell five times when in contact with water is accepted
as good in trade, but better bentonites can swell 10–20 times. The swelling property
of bentonite is lost after a particular temperature. The bentonite which has high
ionization density has a dry density of 2.7–2.8 g/cm
3 , and the dust form has a density
of 1.6–1.7 g/cm
3 [42].
Intercalation of dye molecules (especially organic dyes) in between layers of
inorganic clays are done with different purposes and applications. Bergman et al.
reported the metachromatic behavior of methylene blue that is cationic dye stuff on
clay which is Wyoming montmorillonite as first [38]. After that study, interaction
between organic molecules and clay particles is researched with many studies.
E. Emekdar and U. K. ¸
Sahin
of the silicate. Molecules can penetrate inner layers due to breaking the water in the
inner layer by cations, and it is called hydrophobic adsorption [36]. Van der Waals
or hydrophobic interaction can be seen with ammonium cation alkali chains and
adsorbed nonpolar molecules at gaps of the inner layer. When organic cations are
placed at inner layers, they enlarge layer gaps [37].
Secondary adsorption occurs with Van der Waals forces which are between
adsorbed organic molecules and aliphatic chains of changeable cations. That is why
the secondary adsorption between molecules that have a low polarity or nonpolar
molecules and the long-chained ammonium montmorillonite complexes increases
with the increment of the basal gaps and primary adsorbed organic ions amount [38].
At the experiments that are done with alkali ammonium ions that have different
alkali chain lengths which are used as a surface-active agent, it is seen that the longer
chained alkali ammonium ions (C18-C20) increase the distance between the silicate
layers more than the shorter chained alkali ammonium ions (C9-C10). Also, between
unary, binary, trilogy, and quart onium ions, quart alkali ammonium ions are the most
effective ions that increase one layer distance to another one best [39]. The reason
for this is quart ammonium ions make a strong bond with MMT. This force increases
with the increment of the displaced components of the ammonium cations [40].
The sum of equivalent mass number of changeable cations (meg) at 100 g of the
mineral is called the cation exchange capacity (CEC), and it is a significant parameter
to nominate the most suitable clay type for defined end-use [41].
Bentonite which has a general formula of Al 4 Si 8 O 20 (OH) 4 .nH 2 O is clay that
shows the strong colloidal property, has high plasticity, has a soft handle, and can be
easily shaped. Also, it is an important ion exchanger that swells when it gets into the
water, can be activated by acid, darkens the drilling muds, and has wide surface area
[42, 43]. Inside the bentonite, there are natural clay minerals such as kaolin and illite
and non-clay minerals such as gypsum, quartz, rutile, calcite, dolomite, and volcanic
ash. They are found in nature in many colors such as white, gray, green, yellow, and
pink [42].
The most distinguishing property of bentonites is holding water inside their structure as presented in Fig. 5. Taking water in its structure and widening its crystalline
structure is called swelling. Swelling is directly proportional to the type and amount
of cations between the 2:1 segments. At these segments, generally, there are Na
+ and
Ca
+2 cations, and while the Na
+ /Ca
+2 equimolar ratio increases, the swelling also
increases [44].
The bentonite which can swell five times when in contact with water is accepted
as good in trade, but better bentonites can swell 10–20 times. The swelling property
of bentonite is lost after a particular temperature. The bentonite which has high
ionization density has a dry density of 2.7–2.8 g/cm
3 , and the dust form has a density
of 1.6–1.7 g/cm
3 [42].
Intercalation of dye molecules (especially organic dyes) in between layers of
inorganic clays are done with different purposes and applications. Bergman et al.
reported the metachromatic behavior of methylene blue that is cationic dye stuff on
clay which is Wyoming montmorillonite as first [38]. After that study, interaction
between organic molecules and clay particles is researched with many studies.