CHARACTERIZATION STUDY OF CHITOSAN AS METAL IONS REMOVAL

Removal of certain metal ions from wastewaterby using biopolymers is proved to be
a great alternative at the moment. Chitosan is one of the best examples in removing
heavy metal ions. Its high amino content has been found to possess good sorptive
capacities for many heavy metal ions through complexion of heavy metal ions with
the amine group in chitosan. Chitosan indicates a family of deacetylated chitins.
Chitin ((l-4)-linked 2-acetamido-2-deoxy-p-D-glucan) is widely distributed among
invertebrates. Chitin is extracted from crab shells through demineralization and
deproteination process. Chitosan is obtained by deacetylation of chitin in
concentrated sodium hydroxide (NaOH). The efficiency of metal ions removal using
chitosan is tested against oily wastewater. The presence of metal ions in sample
solution is measured using Flame Atomic Absorption Spectrometry (FAAS). The
weight percentage of chitin extracted from crab shells powder is 45.51 wt %. The
weight percentage of chitosan yield from the deacetylation process is 69.94 wt %.
The study of the influence of dose of chitosan and effect of contact time gives the
expected result. As the dose of chitosan added to the sample oily wastewater
increases, the percentage removal of metal ions also increases. The percentage
removal of zinc, lead and iron at optimum doseof chitosan addedis 89.08%, 84.00%,
and 61.36% accordingly. Increasing the contact time also results in increases of
percentage removal of metal ions. The percentage removal of zinc, lead, and iron at
optimum contact time is 93.70%, 78.85%, and 65.58% accordingly. From the results
obtained, the selectivity of chitosan to metal ions decreased in order Zn > Pb >
Fe2+.