Adsorptive Capacity of Water Hyacinth on Heavy Metals

Abstract

The adsorptive capacity of activated water hyacinth (AWH) on lead (Pb++) and iron (Fe++) was studied. The zinc chloride activated carbons were characterized under pH and iodine number, moisture content, particle size, specific gravity, bulk density, porosity and volume of void. Batch adsorption studies were also carried out under varying experimental conditions of pH of the solutions, contact time of the carbons and metal ions, and initial concentration of Pb++ and Fe++ solutions. The results showed that the highest percentage removal of 99.85 occurred at pH = 8 by AWH on Fe++ and the lowest % removal of 3.03 on the same metal and iodine number of 620mg/g. Although a pH of 7.0 is recommended because of treatment of consumables.

On the effect of contact time, it was found that the equilibrium time for the sorption was at 60mins with the percentage removal of 99.59 by AWH on Fe. On the effect of initial concentration, the results showed that the adsorption of Fe increases with the initial concentration, while that of Pb++ decreases with the increase in initial concentration. The

Langmuir and Freundlich isotherm gave values of 0.692 and 0.771 correlation coefficients respectively for lead, which indicate poor modeling ability of the AWH and entirely inadequate for modeling that of iron.