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or by grafting enhances their performance, strength, and reusability. The char and
activated carbon prepared from cheap cellulosic sources may even replace the costly
commercial activated carbon. The performances of modified cellulose, cellulose
beads, grafted cellulose, cellulosic composites, nano-cellulose, and hydrogels on
heavy metal eradication have been elaborated. A broad list of different cellulosebased adsorbents and their adsorption capacities has been compiled, which indicates their significant comparable metal removal capacities with the commercial
adsorbents. Moreover, most of the modified adsorbents have strong regeneration
ability and are reusable in many cycles efficiently with a feasibility of metal
recovery.
Keywords Cellulose · Heavy metal ions · Adsorption · Isotherm · Langmuir ·
Freundlich · Microcrystalline cellulose · Nano-cellulose · Grafted cellulose
composites · Hydrogel · Cellulose beads
5.1 Introduction
Water contamination is a severe problem to the mankind (Darabos et al. 2015; Li
et al. 2013). Though human body needs some of the heavy metals in small concentrations, lead, arsenic, mercury, cadmium, chromium, copper, iron, zinc, and nickel
are very toxic in nature. They affect the enzyme systems and the metabolism of our
body at even small doses (Li et al. 2013; Paulino et al. 2006). Exposure to these elements may cause immediate as well delayed adverse health effects like skin disease,
digestion and respiratory problems, cancer, etc. People follow various wellestablished techniques since long to eradicate these pollutants from the wastewater
or to minimize their level. Research and development has revealed various new
directions for exclusion of toxic pollutants, especially heavy metals from water and
wastewater, and adsorption is considered as one of the most sustainable, clean,
cheap, and eco-friendly processes for solving these problem. Compared to other
methods, adsorption process produces minimum biological or chemical sludge and
has the potential of metal recovery, and the spent adsorbent may be burnt as fuel
(Volesky 1990). Activated carbon is a very effective adsorbent and widely used, but
its high cost is compelling people to find out other suitable materials (Khan et al.
2004). Large amounts of wastes are available from forest, as agricultural residues.
Agricultural and biowaste materials contain lignin, cellulose, and hemicellulose and
have a wide variety of hydroxyl, alcoholic, phenolic, and other functional groups
which make them suitable for metal binding (Demirbas 2008). Cellulose is one of
the main constituents of the natural wastes, by-products, and residues from a number of food processing industries. Photosynthesis process generates nearly 1 lakh
crore tons of cellulose yearly throughout the world (O’Connell et al. 2008). Due to
the abundant availability without much cost, these materials can be applied for elimination of heavy metals with or without modifications. Cellulose is often extracted
S. Nag and S. Biswas
or by grafting enhances their performance, strength, and reusability. The char and
activated carbon prepared from cheap cellulosic sources may even replace the costly
commercial activated carbon. The performances of modified cellulose, cellulose
beads, grafted cellulose, cellulosic composites, nano-cellulose, and hydrogels on
heavy metal eradication have been elaborated. A broad list of different cellulosebased adsorbents and their adsorption capacities has been compiled, which indicates their significant comparable metal removal capacities with the commercial
adsorbents. Moreover, most of the modified adsorbents have strong regeneration
ability and are reusable in many cycles efficiently with a feasibility of metal
recovery.
Keywords Cellulose · Heavy metal ions · Adsorption · Isotherm · Langmuir ·
Freundlich · Microcrystalline cellulose · Nano-cellulose · Grafted cellulose
composites · Hydrogel · Cellulose beads
5.1 Introduction
Water contamination is a severe problem to the mankind (Darabos et al. 2015; Li
et al. 2013). Though human body needs some of the heavy metals in small concentrations, lead, arsenic, mercury, cadmium, chromium, copper, iron, zinc, and nickel
are very toxic in nature. They affect the enzyme systems and the metabolism of our
body at even small doses (Li et al. 2013; Paulino et al. 2006). Exposure to these elements may cause immediate as well delayed adverse health effects like skin disease,
digestion and respiratory problems, cancer, etc. People follow various wellestablished techniques since long to eradicate these pollutants from the wastewater
or to minimize their level. Research and development has revealed various new
directions for exclusion of toxic pollutants, especially heavy metals from water and
wastewater, and adsorption is considered as one of the most sustainable, clean,
cheap, and eco-friendly processes for solving these problem. Compared to other
methods, adsorption process produces minimum biological or chemical sludge and
has the potential of metal recovery, and the spent adsorbent may be burnt as fuel
(Volesky 1990). Activated carbon is a very effective adsorbent and widely used, but
its high cost is compelling people to find out other suitable materials (Khan et al.
2004). Large amounts of wastes are available from forest, as agricultural residues.
Agricultural and biowaste materials contain lignin, cellulose, and hemicellulose and
have a wide variety of hydroxyl, alcoholic, phenolic, and other functional groups
which make them suitable for metal binding (Demirbas 2008). Cellulose is one of
the main constituents of the natural wastes, by-products, and residues from a number of food processing industries. Photosynthesis process generates nearly 1 lakh
crore tons of cellulose yearly throughout the world (O’Connell et al. 2008). Due to
the abundant availability without much cost, these materials can be applied for elimination of heavy metals with or without modifications. Cellulose is often extracted
S. Nag and S. Biswas