128
adsorption, respectively (O’Connell et al. 2006). Some others (Wu et al. 2012) modified the adsorbent cotton, sawdust, and wheat hull with thioglycolic acid, acetic
anhydride, acetic acid, and concentrated sulfuric acid to form thiol-functionalized
adsorbents and tried these modified stuffs for trimming down Pb(II) from glucose
solution. The thiol-modified adsorbents had nearly two to three times better performance compared to the unmodified one. Another cellulose-based adsorbent was
synthesized and used (Zhou et al. 2014) for eradication of Pb(II), and excellent
adsorption capacity (584.80 mg g
−1
) was recorded. The sorption obeyed Langmuir
model and second-order rate equation. They also found that the adsorbent was ecofriendly, had good regeneration ability, and can be reused for at least six times.
Others (He et al. 2014) synthesized polyethyleneimine-modified porous cellulosic
material and got excellent result for Cr(III) and Fe(III) removal. The new adsorbent
had six times reusability. Table 5.8 depicts the performances of the different modified adsorbents.
Cellulose Beads
Environment-friendly beads were prepared by many researchers and were applied
successfully for heavy metal eradication. A new adsorbent in the form of spherical
cellulose beads was prepared after chemical modification of cotton and named as
spherical cellulose adsorbent for metal ions, and both adsorption and desorption
studies were conducted for Cu(II). The bead had enhanced area of 189.12 m
2
g
−1
and Langmuir uptake of 83.56 mg g
−1
at 40 °C. They had good regeneration capacity, and only 7.2% of its initial adsorption power was lost after three cycles (Liu
et al. 2002). A biodegradable chitin/cellulose bead was prepared by others (Zhou
et al. 2004) and that could effectively treat lead, cadmium, and copper. 98% performance was regained using 1 M HCl solution. Chitosan–cellulose hydrogel beads
were synthesized (Li and Bai 2005) by blending chitosan with cellulose and crosslinking with ethylene glycol diglycidyl ether. Both the beads were applied for copper remediation, and high adsorption capacity was achieved by both the chitosan
cellulose and cross-linked chitosan-cellulose hydrogel beads. However, cross-linked
chitosan beads had little less adsorption capacity. Scientists (Luo et al. 2016) fabricated magnetic cellulose beads by using nitric acid-modified activated carbon from
cotton linter pulp and surrounded with carboxyl-decorated magnetic nanoparticles.
They tried this chemically modified beads for Cu(II), Pb(II), and Zn(II) eradication.
The micro- and nano-porous structure of the beads contributed in high metal ion
adsorption. The process was spontaneous and endothermic in nature. Almond shell
was bleached with 1-butyl-3-methylimidazolium chloride and coagulated and
freeze-dried to synthesize a novel adsorbent, named as cellulose bead-based biosorbents. The surface was modified to 3D macroporous structure with interconnected
pores and the beads efficiently removed Cu(II) (Maaloul et al. 2019).
S. Nag and S. Biswas
adsorption, respectively (O’Connell et al. 2006). Some others (Wu et al. 2012) modified the adsorbent cotton, sawdust, and wheat hull with thioglycolic acid, acetic
anhydride, acetic acid, and concentrated sulfuric acid to form thiol-functionalized
adsorbents and tried these modified stuffs for trimming down Pb(II) from glucose
solution. The thiol-modified adsorbents had nearly two to three times better performance compared to the unmodified one. Another cellulose-based adsorbent was
synthesized and used (Zhou et al. 2014) for eradication of Pb(II), and excellent
adsorption capacity (584.80 mg g
−1
) was recorded. The sorption obeyed Langmuir
model and second-order rate equation. They also found that the adsorbent was ecofriendly, had good regeneration ability, and can be reused for at least six times.
Others (He et al. 2014) synthesized polyethyleneimine-modified porous cellulosic
material and got excellent result for Cr(III) and Fe(III) removal. The new adsorbent
had six times reusability. Table 5.8 depicts the performances of the different modified adsorbents.
Cellulose Beads
Environment-friendly beads were prepared by many researchers and were applied
successfully for heavy metal eradication. A new adsorbent in the form of spherical
cellulose beads was prepared after chemical modification of cotton and named as
spherical cellulose adsorbent for metal ions, and both adsorption and desorption
studies were conducted for Cu(II). The bead had enhanced area of 189.12 m
2
g
−1
and Langmuir uptake of 83.56 mg g
−1
at 40 °C. They had good regeneration capacity, and only 7.2% of its initial adsorption power was lost after three cycles (Liu
et al. 2002). A biodegradable chitin/cellulose bead was prepared by others (Zhou
et al. 2004) and that could effectively treat lead, cadmium, and copper. 98% performance was regained using 1 M HCl solution. Chitosan–cellulose hydrogel beads
were synthesized (Li and Bai 2005) by blending chitosan with cellulose and crosslinking with ethylene glycol diglycidyl ether. Both the beads were applied for copper remediation, and high adsorption capacity was achieved by both the chitosan
cellulose and cross-linked chitosan-cellulose hydrogel beads. However, cross-linked
chitosan beads had little less adsorption capacity. Scientists (Luo et al. 2016) fabricated magnetic cellulose beads by using nitric acid-modified activated carbon from
cotton linter pulp and surrounded with carboxyl-decorated magnetic nanoparticles.
They tried this chemically modified beads for Cu(II), Pb(II), and Zn(II) eradication.
The micro- and nano-porous structure of the beads contributed in high metal ion
adsorption. The process was spontaneous and endothermic in nature. Almond shell
was bleached with 1-butyl-3-methylimidazolium chloride and coagulated and
freeze-dried to synthesize a novel adsorbent, named as cellulose bead-based biosorbents. The surface was modified to 3D macroporous structure with interconnected
pores and the beads efficiently removed Cu(II) (Maaloul et al. 2019).
S. Nag and S. Biswas