Chitosan is a polycationic polymer and the N-deacetylated derivative of the natural polymer chitin, the second most abundant polysaccharide found on earth next to cellulose. Effluent produced from the textile industry is considered threatful that can ultimately affects the ecosystem and therefore treatment is necessary. Hence, in this research, we aimed to extract chitosan from the biowaste using mild chemical extraction processes to applying it for the effluent treatment. Methods A, B, C, D, and E were carried out among which first three methods start with demineralization followed by deproteinization and the remaining two methods start with deproteinization followed by demineralization. The obtained yield in this process is called chitin which was further deacetylated to get chitosan. Thus formed chitosan samples are analyzed for color, yield percentage, and degree of deacetylation (DD); further thermogravimetric analysis, water and fat binding capacity, molecular weight and viscosity were determined. Among the five samples, chitosan obtained through Method C has the molecular weight of 365000, solubility of 87%, DD of 87% and viscosity of 714 cP, which is found to be approximately similar to commercially available chitosan that are used for effluent treatment. INTRODUCTION Chitin is a bio-polymer extracted from the crustacean shells that has versatile industrial applications (Muzzarelli, 1977; Poulicek and Jeunjaux 1991; Kramer et al., 1995). The shells of crab have low economic value and are treated as biowaste or sold to animal feed manufacturers (Suchiva et al., 2002). Therefore, this bio-waste can be used to produce value-added products such as chitosan. Chitosan is a polycationic polymer and the N-deacetylated derivative of the natural polymer chitin, the second most abundant polysaccharide found on earth next to cellulose (Alipour et al. 2009; Ignatova et al. 2007). Chitosan is insoluble in water and common organic solvents because of its rigid crystalline structure. It is soluble in acidic aqueous solution if the pH value is less than 6.5 (No et al. 2007). At a higher pH value, the molecule of chitosan may precipitate out of the solution and lose its charges because of deprotonation of the amine groups (No et al. 2007). Chitosan is well known to be non-toxic, biocompatible, biodegradable, biofunctional and hydrophilic. (Deng et al. 2012; Huang et al. 2007; Ignatova et al. 2006; Li et al. 2008). Chitosan could be used as an antimicrobial and antiviral material in the field of biotechnology, pharmaceutics, wastewater treatment, cosmetics, agriculture, food science, and textiles because of its advantageous biological properties (Li et al. 2008; Lim and Hudson 2004; Lu et al. 2012). MATERIALS AND METHODS Collection of Samples Crab shells were collected from the local market in and around Chennai and were placed in a Ziploc bags to avoid further contaminations and are cleaned several times with pure water to separate from the flesh. Collected shells were sundried in a
