Chitin

Chitin is a linear polysaccharide, with β-(1-4)-linked N-acetyl-D-glucosamine. Found in the exoskeletons of crustaceans (crab, shrimp, lobster, insects) & molluscs, as well as the cell walls of algae and fungi, chitin is the second-most naturally abundant polysaccharide after cellulose [1, 2]. Chitin occurs naturally in the polymorphic forms: α, β and γ. The α-polymorphic form of chitin is the most abundant in nature, present in the strong exoskeleton of crustaceans [6]. α-Chitin forms tightly compact anti-parallel chains, favouring strong H-bonding creating the hard structural component of exoskeletons [1, 3]. β-chitin is present in molluscs, particularly squid and cuttlefish, with a parallel arrangement, causing a less stable structure due …show more content…
The increasing interest and research into chitosan can be attributed to the extensive versatility of chitosan as a biopolymer, with applications in the water decontamination, cancer therapy, drug delivery and wound repair, to name a few. The cationic nature of chitosan allows for relatively easy modification of the polymer, in either grafting or cross-linking reactions [1, 7]. Grafting reactions involve the addition of a functional group, usually resulting in the increased adsorption capacity due to increased absorption sites [7]. Cross-linking reactions bind neighbouring chains together, causing a decreased number of adsorption sites due to increased binding between chains [7]. Cross-linking provides greater stability for the polymer, and is often cross-linked using reagents such as epichlorohydrin, diisocyanate, 1,4-butanediol digycidyl ether and glutaraldehyde [3, 7]. Chitosan can form a number of products from these reactions, including hydrogels, membranes, nanofibers, beads, micro/nanoparticles, scaffolds and sponges [1, 2, …show more content…
With increasing population and industrial growth, waters contaminated with dyes leeching from textile, printing and plastic industries pose threats to the marine environment due to reduced photosynthetic activity from decreased sunlight penetration and their non-biodegradable nature. The adsorption method for removing contaminants from the water is the preferred method in water treatment for its low initial costs and simple design and operation of the treatment unit [5]. Chitosan has been tested as a possible alternative to other toxic, non-biodegradable and expensive adsorption compounds, with results showing derivatives in cross-linked beads the most efficient adsorption capacity