ABSTRACT
Water is one of the essential components of nature, frequently polluted by agricultural, industrial, and man-made activities. The exponential growth of population and industrial development has made potable water a rare commodity (Szygu et al. 2009). Chitosan, a biopolymer, is an aminopolysaccharide composed of glucosamine, 2-amino-2-deoxy-β-dglucose. It is prepared by alkaline deacetylation of chitin, a biopolymer extracted from shell sh sources. Chitosan exhibits a variety of physicochemical and biological properties, which could be used in the elds of biotechnology, agriculture, textile, biomedical engineering, food processing, pharmaceuticals, and ophthalmology. It is a weak cationic base insoluble in water and organic solvent but soluble in aqueous acidic solution with many amine (–NH2) and hydroxyl (–OH) groups and acts as a chelate to form complex with metal ion (Zeng et al. 2008, Bina et al. 2009, Renault et al. 2009). The nature of the pollutants present in the water and wastewater depends on the source generation that varies from place to place (Bhatnagar and Sillanpa 2009). Chitosan has been widely used for water treatment to remove the pollutants. It is a well-known biosorbent for metal cations; the reactive amino group binds with metal ion to remove the metal present in the water by ion exchange. Several methods have been used to modify the natural chitosan in order to
CONTENTS
38.1 Introduction ........................................................................................................................ 747 38.2 Physicochemical Characteristics of Chitosan ................................................................ 748
38.2.1 Chitosan as Natural Flocculants or Coagulant ................................................. 749 38.2.2 Separation of Water from Alcohol Mixture ....................................................... 749 38.2.3 Recoveries of Protein from Surimi Wash Water ................................................ 749 38.2.4 Removal of Dyes .................................................................................................... 750 38.2.5 Removal of Phenol ................................................................................................. 750 38.2.6 Removal of Fluoride .............................................................................................. 750 38.2.7 Removal of Metal Ions........................................................................................... 753 38.2.8 Removal of Nitrate ................................................................................................. 753
38.3 Conclusion .......................................................................................................................... 758 References ..................................................................................................................................... 759
improve the adsorption capacity (Miretzky and Cirelli 2009). Water treatment plants face many problems when removing turbidity from raw untreated water to produce drinking water. Inorganic coagulants such as aluminum sulfate (alum) and polyaluminum chloride have been widely used for the removal of raw water turbidity because it is costeffective and easy to handle. However, the sludge obtained from those treatment leads to disposal problems and contains higher aluminum in treated water. Cationic polyelectrolytes have been used as effective coagulants or occulants in which chitosan, a biodegradable, nontoxic, and high-molecular-weight polymer, has also been used as an eco-friendly coagulant and occulant (Chatterjee et al. 2009).
