Advantages And Disadvantages Of Chitosan

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Chitosan is a product obtained from chitin, which has been found in a wide range of natural resources including crustaceans [12, 21, 22] and fungi [11, 18, 23]. The production of chitosan from chitin can be performed by distinct methods[24], but the most common is the process called deacetylation[11, 23] which consists in the removal of the acetyl group and is usually performed with concentrated NaOH at high temperatures[16, 25].

The characteristics of chitosan that may affect its sorption properties should be explain in order to understand the values and limitations of the chitosan used in this experiment. These include the degree of deacetylation, the structural condition and the crystallinity.
The degree of deacetylation has to be greater …show more content…

Chemistry text books explain that because of its small size, copper ions attract ligands, which are species that are rich in electrons and can form co-ordinate covalent bonds (can donate electrons) to form complex ions[28].
When the copper ion is joined to one or more ligands, a coordination complex is formed where the ligands act as electron donors, and the central atom of copper acts as an electron-pair acceptor. This complex has a structure called coordination sphere[2], with four ligands attached to the central atom.

Adsorption is a process where one or more components (adsorbates) are attracted and bonded to the surface of a solid (adsorbent) with which they are in contact[29]. Chitosan is effective in the adsorption of metal ions due to its vast number of amine groups (-NH2) [12, 14, 15], which are the main active sites[11, 12, 14, 18, 21, 30] and the hydroxyl (-OH) groups, which contribute to a lesser extent[11, 14, 18, 21, 30]. Possible adsorption mechanisms of metal ion uptake by chitosan include the formation of ternary complexes, electrostatic repulsion and chelation [14, 31]. The formation of ternary complexes is the mechanism for the adsorption of alkaline and alkaline-earth ions[29], and the electrostatic repulsion occurs in systems concerning chitosan and anions[29], therefore those mechanism …show more content…

This model is less preferred by scholars, who do not usually find evidence of its existence such as data from colorimeters or IV spectrometers. While there is no general consensus for the chelation of copper by chitosan in the actuality, the balance seems to be titled in favour of the pendant model. However, scholars suggest that chelation is extremely dependant on factors such as contact time, temperature, pH and adsorbent dose [36, 37], therefore it is conceivable that this type of chelation occurs in some specific conditions, but probably not as commonly as the pendant

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