Adsorption of Zinc from Aqueous Solution by Using Natural Adsorbents

Several studied have pointed out natural adsorbent efficiently in the removal of
heavy metal ion present in aqueous solution. Contact time, pH and adsorbent
concentration seem to be the major operating parameters in the metal concentration
control. The mechanisms of interactions between metal and solid are a function of pH
and are found to be precipitation, adsorption or ion exchange. The objectives ofthis work
were to study the removal of heavy metal in water by sorption onto date seeds, clove, star
anise and cinnamon. This research was done on lab scale experiments to study efficiency
of date seeds, cloves, star anise and cinnamon powder in removing heavy metals from
aqueous solution. Solutions of varying concentrations of heavy metals of 1,10 and 100
ppm were prepared and added with adsorbent than shake in orbital shaker for 1, 3, 6 and
24 hours. Next, the sample of solution been filtered to remove insoluble material and
analyzed for concentration of heavy metal ions using spectrophotometer. Concentrations
of adsorbent also were varied to study the removal efficiency of heavy metals. Final
metal ion concentrations in solution and adsorption isotherm were determined. Base on
the experiment, date seeds, clove, star anise and cinnamon shown 92, 91, 82 and 87
percentage of zinc removal. While adsorption capacity was obtained 1.58 mg/g for date,
3.03 mg/g for clove, 0.68 mg/g for star anise and 5.44 mg/g for cinnamon. Kf value for
date seed, clove, star anise and cinnamon was 1.41, 3.5, 0.54 and 3.57. While the value
for n for date seeds, clove, star anise and cinnamon was 1.48, 1.06, 0.54 and 3.57. The
pH for clove, star anise and cinnamon were in range of 4 to 7 pH. While date seeds were
in range of 5 to 8 pH. All the results is consistent with the Freundlich parameter that
indicate, the smaller the value of 1/n means that adsorption bond is strong.