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5.5 Uses of Cellulose-Based Materials for Heavy
Metal Removal
Agricultural materials and their wastes normally have high cellulose content, and
these materials have been used by many scientists as adsorbents without any modifications. But some of them have considerable amounts of hemicelluloses, lignin,
pectin, etc. along with cellulose; they are physically or chemically modified for use
as adsorbents (Jamshaid et al. 2017). Pretreatment using various kinds of acid or
base solutions or salts increases the metal ion adsorption efficiency. Dilute sulfuric
acid improves hydrolysis of cellulose and achieves high reaction rates; however,
concentrated acid was not recommended due to its toxicity (Esteghlalian et al. 1997).
5.5.1 Sugarcane Bagasse
Bagasse is a cellulose-rich material (50%) and contains hydroxyl and phenolic
groups. It is used in both treated and untreated forms. Khan et al. worked on sugarcane bagasse for Cr
+6
removal and obtained promising results (Khan et al. 2001).
Rao et al. treated the waste bagasse from sugar industry with NaOH and is used for
Cr(VI) and Ni(II) removal. They compared the results with commercial powdered
activated carbon and observed that bagasse was effective and cost comparative over
the activated carbon for both the metal ions. They suggested its use in wastewater
treatment (Rao et al. 2002). Some other researchers treated Cd
+2
and Zn
+2
laden
solution by using activated carbon made from sugarcane bagasse heated at
800–850 °C. The reaction was endothermic, and the adsorption capacity increased
with temperature for both metal ions (Mohan and Singh 2002). Bagasse fly ash was
treated with hydrogen peroxide and attempted (Gupta and Ali 2004) for exclusion
of Pb(II) and Cr(VI). 96–98% elimination of metal ions was observed at low flow
rates in column. The chemically modified sugarcane bagasse was attempted (Karnitz
Jr. et al. 2007) for remotion of copper, cadmium, and lead ions. The treatment was
done initially with succinic anhydride to synthesize the modified sugarcane bagasse
containing carboxylate functions and further to introduce chelating functions of
amide groups. The modified sugarcane showed better performance for all metal
ions, and the removal efficiency was related directly to the amide functions introduced from outside. Another group of scientists used native sugarcane bagasse and
modified it after anaerobic degradation and used it for adsorption of both Cd(II) and
Zn(II). The improved sugarcane bagasse (after anaerobic degradation) had 2 times
more adsorption capacity for Zn(II) and 2.3 times for Cd(II) compared to the native
one; moreover, the anaerobic degradation process yielded biogas (Joseph et al.
2009). Cellulose and sugarcane bagasse were mercerized with NaOH and then
treated with EDTA (Junior et al. 2009) and tried for copper, cadmium, and lead
management. They observed that the mercerized form displayed better results compared to non-mercerized form for both the cellulose and sugarcane bagasse.
5 Cellulose-Based Adsorbents for Heavy Metal Removal
5.5 Uses of Cellulose-Based Materials for Heavy
Metal Removal
Agricultural materials and their wastes normally have high cellulose content, and
these materials have been used by many scientists as adsorbents without any modifications. But some of them have considerable amounts of hemicelluloses, lignin,
pectin, etc. along with cellulose; they are physically or chemically modified for use
as adsorbents (Jamshaid et al. 2017). Pretreatment using various kinds of acid or
base solutions or salts increases the metal ion adsorption efficiency. Dilute sulfuric
acid improves hydrolysis of cellulose and achieves high reaction rates; however,
concentrated acid was not recommended due to its toxicity (Esteghlalian et al. 1997).
5.5.1 Sugarcane Bagasse
Bagasse is a cellulose-rich material (50%) and contains hydroxyl and phenolic
groups. It is used in both treated and untreated forms. Khan et al. worked on sugarcane bagasse for Cr
+6
removal and obtained promising results (Khan et al. 2001).
Rao et al. treated the waste bagasse from sugar industry with NaOH and is used for
Cr(VI) and Ni(II) removal. They compared the results with commercial powdered
activated carbon and observed that bagasse was effective and cost comparative over
the activated carbon for both the metal ions. They suggested its use in wastewater
treatment (Rao et al. 2002). Some other researchers treated Cd
+2
and Zn
+2
laden
solution by using activated carbon made from sugarcane bagasse heated at
800–850 °C. The reaction was endothermic, and the adsorption capacity increased
with temperature for both metal ions (Mohan and Singh 2002). Bagasse fly ash was
treated with hydrogen peroxide and attempted (Gupta and Ali 2004) for exclusion
of Pb(II) and Cr(VI). 96–98% elimination of metal ions was observed at low flow
rates in column. The chemically modified sugarcane bagasse was attempted (Karnitz
Jr. et al. 2007) for remotion of copper, cadmium, and lead ions. The treatment was
done initially with succinic anhydride to synthesize the modified sugarcane bagasse
containing carboxylate functions and further to introduce chelating functions of
amide groups. The modified sugarcane showed better performance for all metal
ions, and the removal efficiency was related directly to the amide functions introduced from outside. Another group of scientists used native sugarcane bagasse and
modified it after anaerobic degradation and used it for adsorption of both Cd(II) and
Zn(II). The improved sugarcane bagasse (after anaerobic degradation) had 2 times
more adsorption capacity for Zn(II) and 2.3 times for Cd(II) compared to the native
one; moreover, the anaerobic degradation process yielded biogas (Joseph et al.
2009). Cellulose and sugarcane bagasse were mercerized with NaOH and then
treated with EDTA (Junior et al. 2009) and tried for copper, cadmium, and lead
management. They observed that the mercerized form displayed better results compared to non-mercerized form for both the cellulose and sugarcane bagasse.
5 Cellulose-Based Adsorbents for Heavy Metal Removal