101
decrease in Cd(II) adsorption was attributed to “blocking effect” between humic
acid and bacterial cells (Du et al. 2016b).
In another study, Cu(II) adsorption on montmorillonite–alginate microcapsules
at pH 5 and at different montmorillonite–alginate ratios was performed by Ely et al.
and showed that the increase in montmorillonite–alginate ratio caused decrease in
heavy metal adsorption. When montmorillonite amount is higher, the intercalation
of alginate into clay layers disables the interaction of functional groups of alginate
with heavy metal ion. The kinetics of the metal adsorption was explained by pseudosecond- order model (Ely et al. 2009).
Alginate–montmorillonite–polyaniline nanocomposite was fabricated by Olad
and Azhar by performing chemical oxidative polymerization of aniline in alginate–
montmorillonite nanocomposite dispersion. This nanocomposite was used to Cr(VI)
uptake from aqueous solution. Cr(VI) adsorption was described by pseudo-secondorder model, while adsorption isotherm fitted Freundlich model. It was implied that
the Cr(VI) sorption was endothermic reaction. Additionally, it was observed that
adsorbed amount of Cr(VI) on alginate–montmorillonite–polyaniline nanocomposite was higher than that on alginate–montmorillonite. On the other hand, the adsorption on alginate–montmorillonite composite was lower than the adsorption on
alginate–polyaniline. This situation was explained by the intercalation of alginate
into silicate layers of montmorillonite preventing Cr(VI) to penetrate into montmorillonite layers (Olad and Azhar 2014).
Ni(II) and Mn(II) adsorption onto montmorillonite–rice husk composite, fabricated by furnace at 300
°
C, was done by comparing the result with obtained results
for heavy metal adsorption on unmodified montmorillonite. It was expressed that
the surface area and total pore volume of the composite were dramatically higher
than those of unmodified montmorillonite, while the mean pore diameter was
smaller. The improved microstructural properties resulted in the enhancement of
cation exchange and adsorption properties. Mn(II) and Ni(II) adsorptions were
expressed by the Freundlich isotherm model, but the maximum adsorption capacities were calculated using the linearized Langmuir model because the determination
coefficient was high enough. The addition of rice husk to montmorillonite enabled
to have more efficient and cheaper novel adsorbent for environmental remediation
(Akpomie and Dawodu 2015).
Charcoal and active carbon are also considered as biosorbents (Wang and Chen
2009; Reddy and Reddy 2014; Kırbıyık et al. 2016). In a study, activated carbon–
montmorillonite–thiolated graphene oxide composite was used to removal of Pb(II).
The fast sorption occurred in 20 min with the pseudo-second-order kinetic. The
maximum Pb(II) adsorption capacity of fabricated composite was approximately
1 mmol/g. The high adsorption of Pb(II) was explained by chemical and electrostatic interaction between Pb(П) and composite surface having many donor groups
such as carboxyl and hydroxyl groups. The authors suggested the activated carbon–
montmorillonite–thiolated graphene oxide composite as a high-performance adsorbent for Pb(П) removal from polluted water (Mojoudi et al. 2019).
4 Montmorillonite Clay Composite for Heavy Metal Removal from Water
decrease in Cd(II) adsorption was attributed to “blocking effect” between humic
acid and bacterial cells (Du et al. 2016b).
In another study, Cu(II) adsorption on montmorillonite–alginate microcapsules
at pH 5 and at different montmorillonite–alginate ratios was performed by Ely et al.
and showed that the increase in montmorillonite–alginate ratio caused decrease in
heavy metal adsorption. When montmorillonite amount is higher, the intercalation
of alginate into clay layers disables the interaction of functional groups of alginate
with heavy metal ion. The kinetics of the metal adsorption was explained by pseudosecond- order model (Ely et al. 2009).
Alginate–montmorillonite–polyaniline nanocomposite was fabricated by Olad
and Azhar by performing chemical oxidative polymerization of aniline in alginate–
montmorillonite nanocomposite dispersion. This nanocomposite was used to Cr(VI)
uptake from aqueous solution. Cr(VI) adsorption was described by pseudo-secondorder model, while adsorption isotherm fitted Freundlich model. It was implied that
the Cr(VI) sorption was endothermic reaction. Additionally, it was observed that
adsorbed amount of Cr(VI) on alginate–montmorillonite–polyaniline nanocomposite was higher than that on alginate–montmorillonite. On the other hand, the adsorption on alginate–montmorillonite composite was lower than the adsorption on
alginate–polyaniline. This situation was explained by the intercalation of alginate
into silicate layers of montmorillonite preventing Cr(VI) to penetrate into montmorillonite layers (Olad and Azhar 2014).
Ni(II) and Mn(II) adsorption onto montmorillonite–rice husk composite, fabricated by furnace at 300
°
C, was done by comparing the result with obtained results
for heavy metal adsorption on unmodified montmorillonite. It was expressed that
the surface area and total pore volume of the composite were dramatically higher
than those of unmodified montmorillonite, while the mean pore diameter was
smaller. The improved microstructural properties resulted in the enhancement of
cation exchange and adsorption properties. Mn(II) and Ni(II) adsorptions were
expressed by the Freundlich isotherm model, but the maximum adsorption capacities were calculated using the linearized Langmuir model because the determination
coefficient was high enough. The addition of rice husk to montmorillonite enabled
to have more efficient and cheaper novel adsorbent for environmental remediation
(Akpomie and Dawodu 2015).
Charcoal and active carbon are also considered as biosorbents (Wang and Chen
2009; Reddy and Reddy 2014; Kırbıyık et al. 2016). In a study, activated carbon–
montmorillonite–thiolated graphene oxide composite was used to removal of Pb(II).
The fast sorption occurred in 20 min with the pseudo-second-order kinetic. The
maximum Pb(II) adsorption capacity of fabricated composite was approximately
1 mmol/g. The high adsorption of Pb(II) was explained by chemical and electrostatic interaction between Pb(П) and composite surface having many donor groups
such as carboxyl and hydroxyl groups. The authors suggested the activated carbon–
montmorillonite–thiolated graphene oxide composite as a high-performance adsorbent for Pb(П) removal from polluted water (Mojoudi et al. 2019).
4 Montmorillonite Clay Composite for Heavy Metal Removal from Water