Introduction Opm.docx

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Introduction Today’s world is faced with serious dangers of air, land and water

pollutions. Water pollution in particular, has raised serious concerns. In addition to the shortage of resources of water, production of large volumes of wastewater has put a lot of pressure on the humankind. The conventional technologies like coagulation flocculation, oxidation, membrane separation, ion exchange, electro precipitation, evaporation and floatation are inadequate to deal with the wastewater treatment problem. Adsorption is known to be one of the best of the technologies for the decontamination of water. Even though activated carbon based technology is still used for treating wastewater, it is not cost and energy efficient. Hence adsorption using low cost adsorbents has become an attractive choice. Biopolymers such as chitosan and cellulose present an interesting option (Kalia & Avérous, 2011). A number of studies have been made for the adsorptive removal of heavy metals and dyes utilizing cellulose and chitosan based materials (Ahmad, Ahmed, Swami & Ikram, 2015; Güçlü, Gürdağ & Özgümüş, 2003; No & Meyers, 2000; O’Connell, Birkinshaw & O’Dwyer, 2008; Zhou, Zhang, Zhou & Guo, 2004). Cellulose and chitosan constitute the first and second most abundant biopolymers on earth. They are natural, renewable, environmentally benign, cost efficient, non toxic, biodegradable and biocompatible (Crini & Badot, 2008). Cellulose is majorly derived from plant sources such as grasses, reeds, stalks and woody parts of the vegetation. Animals, algae, fungi, amoebae, cellular slime molds, green algae and bacteria also contribute in the production of celluloses (Azizi Samir, Alloin & Dufresne, 2005). Cellulose consists of over ten thousand repeating units of β (l→4)–D–glucose linkages and has the formula (C 6H10O5)n while chitosan which is normally derived from de–acetylation of chitin is made up of β–(l→4) linkages of N–acetyl–D glucosamine and D–glucosamine. Chitosan is found mainly in crustacean shells such as shrimp, crab, lobster, crawfish, and cell walls of fungi as well as cuticles of insects (Jayakumar, Tamura, Prabaharan, Kumar, Nair & Furuike, 2011).

With the advancement in nanosciences, development of cellulose and chitosan based materials having nano sizes has become possible. Cellulose and chitosan nanoparticles/nanocomposites become materials of choice because of attractive surface area, chemical accessibility, ease of functionalization and absence of internal diffusion (Chang, Chang & Chen, 2006; Hokkanen, Repo, Suopajärvi, Liimatainen, Niinimaa & Sillanpää, 2014; Suman, Kardam, Gera & Jain, 2015). A fairly good amount of literature is available for the adsorption of heavy metals and dyes by employing these potential adsorbents. REFERENCES Ahmad, M., Ahmed, S., Swami, B. L., & Ikram, S. (2015). Adsorption of heavy metal ions: role of chitosan and cellulose for water treatment. Langmuir, 79, 109-155. Azizi Samir, M. A. S., Alloin, F., & Dufresne, A. (2005). Review of recent research into cellulosic whiskers, their properties and their application in nanocomposite field. Biomacromolecules, 6(2), 612-626. Chang, Y.-C., Chang, S.-W., & Chen, D.-H. (2006). Magnetic chitosan nanoparticles: Studies on chitosan binding and adsorption of Co (II) ions. Reactive and functional polymers, 66(3), 335- 341. Crini, G., & Badot, P.-M. (2008). Application of chitosan, a natural aminopolysaccharide, for dye removal from aqueous solutions by adsorption processes using batch studies: A review of recent literature. Progress in polymer science, 33(4), 399-447. Güçlü, G., Gürdağ, G., & Özgümüş, S. (2003). Competitive removal of heavy metal ions by cellulose graft copolymers. Journal of Applied Polymer Science, 90(8), 2034-2039. Hokkanen, S., Repo, E., Suopajärvi, T., Liimatainen, H., Niinimaa, J., & Sillanpää, M. (2014). Adsorption of Ni (II), Cu (II) and Cd (II) from aqueous solutions by amino modified nanostructured microfibrillated cellulose. Cellulose, 21(3), 1471-1487.

Jayakumar, R., Tamura, H., Prabaharan, M., Kumar, P. S., Nair, S., & Furuike, T. (2011). Novel chitin and chitosan materials in wound dressing. INTECH Open Access Publisher. Kalia, S., & Avérous, L. (2011). Biopolymers: biomedical and environmental applications. John Wiley & Sons. No, H. K., & Meyers, S. P. (2000). Application of chitosan for treatment of wastewaters. Reviews of Environmental contamination and Toxicology (pp. 1-27): Springer. O’Connell, D. W., Birkinshaw, C., & O’Dwyer, T. F. (2008). Heavy metal adsorbents prepared from the modification of cellulose: A review. Bioresource Technology, 99(15), 6709-6724. Suman, Kardam, A., Gera, M., & Jain, V. (2015). A novel reusable nanocomposite for complete removal of dyes, heavy metals and microbial load from water based on nanocellulose and silver nano-embedded pebbles. Environmental technology, 36(6), 706-714. Zhou, D., Zhang, L., Zhou, J., & Guo, S. (2004). Cellulose/chitin beads for adsorption of heavy metals in aqueous solution. Water research, 38(11), 2643-2650.