Chitosan chelating ability

Metal ions. Chitosan is known to complex metal ions. The chelating ability of chitosan is superior compared to other known biopolymers [30]. This property is widely investigated for its use as sensors or filtration materials in heavy metal ion detection or separation [17, 20a, 31]. The binding of chitosan with metal ions is thought to provide donor atoms that may improve the antimicrobial activity of the material however, studies on this area are quite limited [32]. 

PROPERTIES OF SPECIAL INTEREST Natural resources basic polysaccharides nontoxic biodegradability bioactivity biosynthesis interesting derivatives (chitosan) toughness graft copolymerization chelating ability for transition metal cations immobilizes enzymes by chemical linking or adsorption chiral polymer. 

On the other hand, the chelating ability of chitosan seems to guarantee the absence of release of metal ions to blood. 

Chitosan have good sorption properties. With a large number of functional groups, chitosan-based microspheres have been applied in water treatment to remove metal ions or dyes. Recently, much attention has been paid to the adsorption of metal ions on chitosan, which is proved to be an extremely promising material due to its high chelating ability, higher hydrophilicity, environmentally safe, and abundant base material. Chitosan-based microspheres are well known as an excellent biosorbent for metal cation removal, such as... 

Unlike other naturally occurring polysaccharides, e.g., cellulose, dextran, pectin, alginic acid, agar, agarose and carrageenans, which are neutral or acidic in nature, chitosan is a highly basic polysaccharide. This unique property imparts several functional attributes such as polyoxysalt formation, ability to form films, chelation with metal ions, and optical structural characteristics (Hench 1998). 

In addition, molecular imprinting technique is also used in anion recognition. Ozkutuk et al. reported the preparation and adsorption ability of the phosphate-imprinted chitosan-succinate beads [34]. Chitosan was modified with succinic anhydrides firstly. Second the mixture of chitosan-succinate and Fe (III) ions stirred continuously at room temperature. And Na3P04 was added to Fe (III)-chitosan-succinate mixture. This mixture was slowly dropped into NaOH solution to form beads. Afterwards, beads were crosslinked with epichlorohydrin and the template (phosphate ions) was removed using IM KOH solution. Selective cavity for the phosphate ion was obtained in the phosphate imprinted metal-chelate polymer. The phosphate-imprinted metal-chelate polymer was used in the adsorption-desorption process. The adsorption process was fast and equilibrium was reached around 30 min. The adsorption behaviour of this system was described approximately by the Langmuir equation. 

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