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Cellulose Hydrogels
Hydrogels may be prepared from the natural cellulose in many ways, such as
directly from native celluloses or from cellulose derivatives. Chitosan was blended
with concentrated carboxymethylated cellulose to synthesize carboxymethylated
cellulose/chitosan hydrogels which was then cross-linked by irradiation. This newly
prepared hydrogel was employed for adsorption of Cu(II) in batch technique. Cu(II)
formed complex ions with the amino and carboxyl groups present on the gel, and
the metal uptake was as high as 169.49 mg g
−1
(Zhao and Mitomo 2008). When
compared the performance with the results obtained by previous researchers (Ngah
et al. 2002), they observed that the unsubstituted chitosan and chemically crosslinked chitosan had much less q max values. Zhao and Mitomo suggested adsorption
capacity, and the degree of cross-linking was enhanced by the addition of chitosan.
Cellulose-polymer composite, cellulose-inorganic hybrid hydrogels, etc. are considered as super adsorbents with variety of other applications. The hydrogels are
transparent, non-toxic, and biodegradable. Being a low-cost, environmental-friendly
material, it has the potential to replace the petroleum-based materials in the near
future as a substitute (Chang and Zhang 2011). Liu et al. (2013) worked on magnetic hydrogels. These materials are biocompatible and renewable, indicating good
scope for adsorption applications (Liu et al. 2013).
Nano-cellulose
Succinylated cellulose was synthesized by a series of modifications of microfibrillated cellulose (Hokkanen et al. 2013). Initially, commercially purchased microfibrillated cellulose was mercerized by NaOH solution and then treated with succinic
anhydride and thereafter centrifuged and washed with a number of chemicals to
yield the desired product. These steps helped to convert carboxylic groups to carboxylate which promoted chelating functions. The new material displayed high
adsorption potential for a number of heavy metals, such as zinc, copper, cadmium,
nickel, and cobalt in batch mode with 96 to 100% regeneration efficiency.
5.6 Conclusions
Heavy metal remediation from water and wastewater in a user-friendly way is a
challenging job. The high cost of removal and the operational difficulties often
prompt the small and medium sector industries to bypass the effluent treatment, thus
leading toward a serious environmental degradation. The above study reveals the
potential of cellulosic materials for elimination of toxic heavy metals form wastewater. Cellulose is rich in carbon, economical, and abundantly available from multiple natural sources. They have a natural binding capacity toward heavy metals and
show good adsorption capacity even in untreated condition. Physical and chemical
5 Cellulose-Based Adsorbents for Heavy Metal Removal
Cellulose Hydrogels
Hydrogels may be prepared from the natural cellulose in many ways, such as
directly from native celluloses or from cellulose derivatives. Chitosan was blended
with concentrated carboxymethylated cellulose to synthesize carboxymethylated
cellulose/chitosan hydrogels which was then cross-linked by irradiation. This newly
prepared hydrogel was employed for adsorption of Cu(II) in batch technique. Cu(II)
formed complex ions with the amino and carboxyl groups present on the gel, and
the metal uptake was as high as 169.49 mg g
−1
(Zhao and Mitomo 2008). When
compared the performance with the results obtained by previous researchers (Ngah
et al. 2002), they observed that the unsubstituted chitosan and chemically crosslinked chitosan had much less q max values. Zhao and Mitomo suggested adsorption
capacity, and the degree of cross-linking was enhanced by the addition of chitosan.
Cellulose-polymer composite, cellulose-inorganic hybrid hydrogels, etc. are considered as super adsorbents with variety of other applications. The hydrogels are
transparent, non-toxic, and biodegradable. Being a low-cost, environmental-friendly
material, it has the potential to replace the petroleum-based materials in the near
future as a substitute (Chang and Zhang 2011). Liu et al. (2013) worked on magnetic hydrogels. These materials are biocompatible and renewable, indicating good
scope for adsorption applications (Liu et al. 2013).
Nano-cellulose
Succinylated cellulose was synthesized by a series of modifications of microfibrillated cellulose (Hokkanen et al. 2013). Initially, commercially purchased microfibrillated cellulose was mercerized by NaOH solution and then treated with succinic
anhydride and thereafter centrifuged and washed with a number of chemicals to
yield the desired product. These steps helped to convert carboxylic groups to carboxylate which promoted chelating functions. The new material displayed high
adsorption potential for a number of heavy metals, such as zinc, copper, cadmium,
nickel, and cobalt in batch mode with 96 to 100% regeneration efficiency.
5.6 Conclusions
Heavy metal remediation from water and wastewater in a user-friendly way is a
challenging job. The high cost of removal and the operational difficulties often
prompt the small and medium sector industries to bypass the effluent treatment, thus
leading toward a serious environmental degradation. The above study reveals the
potential of cellulosic materials for elimination of toxic heavy metals form wastewater. Cellulose is rich in carbon, economical, and abundantly available from multiple natural sources. They have a natural binding capacity toward heavy metals and
show good adsorption capacity even in untreated condition. Physical and chemical
5 Cellulose-Based Adsorbents for Heavy Metal Removal