Pre-concentration of trace metals by ICP-AES using chemically- treated and untreated hyacinth weed, Eichhornia crassipes

The trace enrichment of five toxic metals (Cu super(2+), Cd super(2+), Ni super(2+), Pb super(2+) and Zn super(2+)) from aqueous solusions by ICP - AEP using chemically treated and untreated water hyacinth weed biomass was investigated. The data show that highest percent uptake values (97.34% and 96.67% for Cd super(2+) and Zn super(2+), respectively),were obtained by ethanol-treated water hyacinth weed biomass. Further studies were carried out to evaluate the effects of increasing water hardness on metal uptake. The results showed that as water hardness was increased from 0-125 mg CaCO sub(3) 1 super(-1), the equilibrium sorption capacity decreased from 0.671 mg/g to 0.0513 mg/g. Trace enrichment of metal ions from polluted stream water, tape water and borehole water achieved enrichment factors varing from from 11-75, without pre-treatment of the sample. Percent recoveries of 0.025 kg/ml spikes of Cd and Pb in environmental samples varied from 72.6-100%. Dilute HCI proved to be an effective reagent for metal displacement, achieving recoveries ranging from 80-95%. It was also demonstrated that the water hyacinth weed biomass could be regenerated without significant changes in trace enrichment factors (EF values. 31-43 for 5 sorption-desorption cycles). The results from these studies demonstrate that high sorption capacity, easy regeneration and low cost makes water hyacinth weed biomass suitable as a media for trace enrichment of metal ions from aquatic environments.