Use of macrophites for removal of metals in liquid effluents, using instrumental neutron activation analysis

Abstract

This study proposes the application of Eichhornia crassipes biomass, abundant in the dams of São Paulo state, to remove metallic ions from solution, aiming its application to effluent treatment. The efficiency of adsorption was tested by the Zn, Fe, Cr, Co removal from solutions containing these elements. The plants, for biomass production, were collected at the Billings reservoir in São Bernardo do Campo, located in the Southeast of São Paulo Metropolitan Region. After collection, the plants were washed and dried in a ventilated oven from 60 C to 70 C, crushed and passed through a 150 m sieve. The biomass thus obtained was subjected to the chemical activation process by the treatment with 0.1 mol L􀀀1 solution of HCl and 0.1 mol 􀀀1 of NaOH in order to increase its surface area. The tests indicated that the treatment with HCl was the most effective and this was used in the preparation of the biomass for the adsorption tests of the metallic ions. The adsorption tests were carried out, at first, to verify the effect of the pH and the contact time between the sample and the adsorbent in the adsorption process. The concentrations of Zn, Fe, Cr and Co, present in the solution, before and after the treatment, were determined by the instrumental neutron activation analysis (INAA) technique. For this determination the samples were irradiated for 8 hours at the IEA-R1 reactor at IPEN. The concentrations were determined by comparing the peak area of the samples and that of the reference materials irradiated together with the samples.