Extraction of Chitosan from Shrimp Shell: Characterization of Chitosan and Its Application for Removal of Reactive Blue 13 and Acid Green 3 Dyes from an Aqueous Solution

Dyes in industrial wastewater، even at low concentrations، are also highly toxic and carcinogenic، and entry of these substances into the environment causes intense water pollution، impairment of aquatic life and human health، so the removal of these noxious substances are necessary. Also researchers around the world are always looking for easy and affordable methods to clean the environment and industrial wastewater from polluting agents and specifically the dyes. On the other hand، bioabsorbents because of the abundance، availability in nature and eco-friendly nature have attracted much attention. Moreover chitosan is one of the bioabsorbents، which has shown interesting potential for removal of various contaminants (dyes) from wastewater. In this study the extraction of chitosan from shrimp shell and its ability to remove anionic dyes، acid green 3 (AG3) and reactive blue 13 (RB13)، were investigated. Therefore، chitin was extracted by dilute hydrochloric acid followed by dilute sodium hydroxide and finally it was deacetylated by concentrated sodium hydroxide to produce chitosan. The test of color removal in a batch system and also the effects of pH، temperature، contact time and adsorbent dose، were investigated. Chitosan was characterized by XRD، SEM and FTIR. The degree of deacetylation of 70% for chitosan was confirmed by FTIR، and molecular weight of 1. 4 × 105 was obtained by viscometry. Based on these results، the pH and temperature are very important parameters in the removal of both dyes. Also the contact time and amount of adsorbent were considered important for the removal of RB13، but not in case of AG3. Chitosan under optimized conditions is found to remove 89% and 91% of RB13 and AG3، respectively; an indication of the proper functioning of chitosan extracted from shrimp shell in dyes removal.