Precipitation of Heavy Metals Using "Cuttlebone-Citrus Aurantifolia"(CB-CA )

This project presents the research on heavy metals removal from aqueous solution
by chemical precipitation using low cost coagulant which could be used as an
alternative approach to remove heavy metals from water. The low cost coagulants
that are used inremoving heavy metals in aqueous solution were CB which stand for
cuttlebone and CA which stand for (Citrus Aurantifolia) or also known askey lime.
The optimum pH and optimum volume of coagulants were varied for each metals
and it was depend on the characteristics of the heavy metals treated and were
determined from several jar tests performed through out this project. To obtain the
optimum pH, the pH ofthe solutions was set at increased from acidic to alkaline by
adding the CB-CA solution. Each beaker was added 150 ml of heavy metals and
stirrer was operated at 60 rpm for 1 minute for a rapid mix. Then, the rpm was
decreased to 20 rpm for slow mix for 20 minutes. After 20 minutes, stirrer was turn
off and settling was allowed for 20 minutes. The solution then was filtered to
remove the remaining particles that did not settle at the bottom of the beaker. The
volumes of the CB-CA solution added were recorded. Once the optimum pH was
obtained, the optimum volume of CB was determined byvarying the volume added
at the optimum pH level. The volume that results in the most removal was identified
as the optimum volume for the coagulant tested.
The result from this research shows that the CB solution had removed about more
than 90% of heavy metals in aqueous solution which were Copper (Cu), Zinc (Zn)
and Chromium (Cr) and about more than 60% for Cadmium (Cd). The percentage
removal of Copper using CB solution as coagulant was 96.3% at pH 8.1. For Zinc,
the percentage removal was 93.3% at pH 9.7. For Cadmium, the percentage
removal was 60.4% at pH 9.18 and for Chromium, the percentage removal was
98.8% at pH 8.85. This shows that the CB solution had a potential to become the
low cost coagulant that could be the alternative approach to remove heavy metals
from aqueous solution.