Sorption of Heavy Metals onto Nonliving Water Hyacinth Roots

Abstract

Dried water hyacinth (Eichhornio crassipes (Mart.) Solms) roots, when suspended in water, strongly sorb Cd(II) and Pb(II) with Pb(II) more strongly sorbed than Cd(II). The sorption is dependent on factors such as reaction time, pH, concentration of metal ions, temperature, the presence of other metal ions and biomass concentration. In particular. the metal ions are bound to the root biomass in a highly pH dependent manner. Interestingly, Pb(II) is sorbed in concentrations greater than would be expected based on the relative atomic weight of the two metals. The metal ions can readily be desorbed and the roots regenerated. It appears that the roots can be, thus, recycled through at least 50 loading-elution cycles without significant loss of sorption properties. Therefore, there appears to be a considerable advantage to using such dead biomass over the living plants which can be used for only one sorption cycle.

Keywords:

• Aquatic plant biomass
• biosorption
• heavy metals