Biosorption of Uranium with Sargassum filipendula – Use in Treatment of Effluents of Laboratories

摘要

International and National Standards establish methodologies for the management of radioactivewaste in order to comply with radiological protection principles. Thus, it is necessary to find alternatives withboth low cost and effective results. This work studied the use of brown algae Sargassum filipendula in its abilityto remove uranium in waste generated in the environmental analysis laboratories of the Institute of RadiationProtection and Dosimetry. At first, the kinetics of biosorption was studied. This experiment was conducted on abatch at concentrations of 1 mg/L and 100 mg/L. Mathematical models of the first and second order were used tofit the experimental results. In evaluating the maximum removal capacity by marine biomass on a batch,different uranium concentrations were analyzed, and isoterms of biosorption were plotted. The experimentalresults have been adjusted by Langmuir and Freundlich models. The Freundlich model presented the bestcorrelation coefficients (0.99 and 0.94) for studies with an hour and three hours of contact, respectively. In orderto determine the best conditions for removal of uranium using the Sargassum filipendula, it was necessary tohold experiments in a continuous flow. A study on the critical height of bed depth was carried out by filling acolumn with different masses of seaweed. It was obtained a lower outlet concentration of uranium (0.07 mg/L) in40 cm bed depth. This best height of bed was applied to the waste treatment of SEANA laboratories. It wasmonitored the increase of retention in biomass for a known quantity of uranium. The results showed an excellentuptake of uranium (1.25 mg U/g of biomass) even in the presence of other metals and reagents. Decontaminationof the effluent for uranium reached values below those set by CONAMA for water classes I and II, making itpossible to reuse the water.