Removal of metal ions by nonliving water hyacinth roots

Nonliving dried water hyacinth (Eichhornia crassipes (Mart.) Solms) roots w ere investigated for the biosorption of cadmium lead and other heavy metal ions from aqueous solutions. Dried water hyacinth roots, when suspended in solution, strongly and rapidly sorb several different metal ions. Factors s uch as reaction time, pH, the initial concentration of metal ions, the pres ence of other metal ions and biomass concentration were investigated. The a dsorption was shown to follow the generalized Langmuir adsorption equation. The relative affinity of the roots for lend is greater than that for cadmi um. The batch sorption kinetics of the uptake of cadmium and lead can be de scribed by an apparent first-order reversible reaction model. The roots cou ld be regenerated after the metal ions were stripped. Successful desorption of Cd and Pb from the biomass by acidic CaCl2 solutions revealed that the metal uptake phenomenon is reversible, implying physical sorption of Cd and Pb.