EXPER IMENT NO 3 Essays - Chemistry, Polysaccharides, Biopesticides

EXPER IMENT NO 3 Essays - Chemistry, Polysaccharides, Biopesticides EXPER IMENT NO 3 Object: To extract Chitin and Chitosan from Prawn shells. Materials: Prawn shells 5gm 4% HCl solution 1% KMnO 4 4% NaOH solution 1% H 2 C 2 O 4 5 0% Sodium Hydroxide 1% Acetic Acid Theory: Introduction: Chitin is the second most abundant natural polysaccharide after cellulose and is present in the crustacean exoskeleton, insects and fungi. The shell fish industry generates a huge amount of shell waste per processing which usua lly cause environmental pollution . It is estimated that the shell-fish industry produces about 60,000-80,000 tons of waste. The disposal of such an enormous amount of waste has become a serious environmental concern Alternatively, this waste can be utilized as an economic source of chitin and its derivative chitosan. Chitosan, the deacetylated chitin derivative, is a more useful and interesting bioactive polymer. Despite its biodegradability, it can be chemically modified to produce derivatives which have varied applications in biomedical field. These derivatives are easy to produce and can be made commercially available easily. Chitin: Chitin is a biodegradable material and undergoes biodegradation by enzymes such as lysozyme and chitinase . Structure: Chitin is essentially a linear homopolysaccharide (long chain polymer) consisting of repeated units of N-acetyl-glucosamine, which is a monosaccharide derivative of glucose. These units form covalent -1,4 linkages. Chitin with the chemical formula (C 8 H 13 O 5 N) n is considered as a complex carbohydrate, whose structure resembles that of cellulose, with one hydroxyl group on each monomer replaced with an acetyl amine group. Uses: As a fertilizer: Chitin-containing fertilizers are organic, non-toxic, and have shown to increase crop productivity. As a food additive: Microcrystalline chitin (MCC) as a food additive can be helpful to enhance taste and flavor . As an emulsifying agent: It essentially acts as an excellent emulsifying agent, which helps to prevent the breaking of emulsion when exposed to other fluids. Medicinal use: chitin in the diet may help to reduce cholesterol absorption efficiency. As a surgical thread: Chitin is also used for manufacturing strong and flexible surgical threads. Quite a few dissolvable stitches used to close wounds are made from chitin. Chitosan: Chitosan, sometimes known as deacetylated chitin, is a natural polycationic linear polysaccharide derived from partial deacetylation of chitin . Structure: Chitosan is a linear polysaccharide composed of randomly distributed -(1-4) linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). Uses: Agricultural use: Chitosan is used as seed coating and plant growth enhancer. Medicinal use: Chitosan is used to treat obesity , high cholesterol , and Crohn's disease . In pharmaceutical manufacturing, chitosan is used as a filler in tablets; as a carrier in controlled-release drugs; to improve the way certain drugs dissolve; and to mask bitter tastes in solutions taken by mouth . In Chemical Industries: It improves flocculation and is used in filtration process. It is also used as subsidiary material of the colour fixer, patternizer , adhesive and stabilizer in plastic industry. Environmental protection: Chitosan is used as active mud coagulant, adhesive, adsorbent of the heavy metal ion and organic compound. Procedure: Wash and dry the sample. 5gm of shell waste is then Deproteinised in 4% aqueous sodium hydroxide (4gm NaOH in 100ml water) at room temperature for 24 hours. After draining the alkali, for the removal of residual protein from the shell, it was washed with distilled water repeatedly unless the pH drops to neutral . The de - proteinised shell was de -mi neralized by 4% HCl (4ml up to 100ml) at room temperature for 12 hours . The acid was drained off and washed thoroughly with distilled water. The sample is then dried. Soak the dried sample in 1% KMnO 4 ( 1 ml up to 100ml) for 30 minutes followed by 1% H 2 C 2 O 4 for 30 minutes to 2 hours. The cake obtained is chitin. The Chitosan was prepared by deacetylation of chitin by treating with 50% aqueo us sodium hydroxid e at 40 C for 3 days. After deacetylation, the alkali was drained off and washed with distilled water thoroughly until the pH is less than 7.5. Finally, t he chitosan was dried at room temperature