Biomassas brasileiras aplicadas à remoção de urânio de drenagem ácida de minas por processos de biossorção

Abstract

Resumo: Este trabalho teve como objetivo avaliar a redução da concentração de urânio em área de drenagem ácida de mina. O Brasil possui a sexta maior reserva de urânio do mundo e há grande quantidade de rejeitos acumulados contendo íons metálicos, semimetálicos e radiotóxicos. O método utilizado neste estudo para remover urânio foi a biossorção mediante a aplicação de biomassas brasileiras. Os efluentes aplicados foram coletados na mina Osamu Utsumi, que pertence às Indústrias Nucleares do Brasil e os biossorventes empregados nos ensaios foram cascas de banana, semente de moringa e borra de café. A decomposição térmica, a porosimetria de adsorção de nitrogênio e a microscopia eletrônica de varredura (MEV) foram realizadas para caracterizar fisicamente os biossorventes. A partir dos resultados obtidos, observou-se que os biossorventes com maior área de superfície e maior volume de poros resultaram em maiores valores de eficiência de remoção, com uma ordem crescente desses parâmetros: cascas de banana < borra de café < sementes de moringa. Considerando as amostras de efluentes com concentração de urânio de 6 mg L -1 , as sementes de moringa apresentaram remoção de aproximadamente 87%, enquanto a borra de café e cascas de banana apresentaram remoção de 74 e 56%, respectivamente.Palavras-chave: Adsorção de urânio. Drenagem ácida de mina. Casca de banana. Semente de moringa. Borra de café.Abstract: This work aimed to evaluate the uranium concentration reduction in acid mine drainage. Brazil owns the sixth biggest uranium reserve in the world and there is large amount of accumulated tailings containing metallic, semi-metallic and radiotoxic ions. The method used in this study to remove uranium was biosorption by applying Brazilian biomass. The applied effluents were collected at the Osamu Utsaumi mine, which belongs to Industries Nucleares of Brazil and the biosorbents used in the tests were banana peel, moringa seed and spent coffee ground. Thermal decomposition, nitrogen adsorption porosimetry and scanning electron microscopy (SEM) were performed in order to characterize the biosorbents physically. From the results, it was observed that the biosorbents with a higher surface area and higher pore volume resulted in higher removal efficiency values, with an ascending order of these parameters: banana peels

Biochar Derived from Water Hyacinth Biomass Chemically Activated for Dye Removal in Aqueous Solution

“…The micrograph confirms that the LAB and SAB have a porous nature and fundamental and desired characteristics in an adsorbent [67], making them potent biochar in adsorption applications [65]. Although the LAB and SAB have the same structure, they are separate studies since morphology and porosity can influence adsorption capacity [67]. The FTIR spectra of LAB and SAB are found in Figure 1b, where it is possible to observe a few bands, suggesting the existence of a limited variety of surface groups.…”

“…The micrograph confirms that the LAB and SAB have a porous nature and fundamental and desired characteristics in an adsorbent [67], making them potent biochar in adsorption applications [65]. Although the LAB and SAB have the same structure, they are separate studies since morphology and porosity can influence adsorption capacity [67].…”

“…These cavities were generated during the carbonization process due to chemical activation with ZnCl 2 [65], which may facilitate the dye penetration into the biochar pores of the product [66]. The micrograph confirms that the LAB and SAB have a porous nature and fundamental and desired characteristics in an adsorbent [67], making them potent biochar in adsorption applications [65]. Although the LAB and SAB have the same structure, they are separate studies since morphology and porosity can influence adsorption capacity [67].…”

Application of Water Hyacinth Biomass (Eichhornia crassipes) as an Adsorbent for Methylene Blue Dye from Aqueous Medium: Kinetic and Isothermal Study

“…Figure 1e,f, referring to part of the water hyacinth leaf, shows nonhomogeneous structures with some cavities, thus justifying the need to carry out studies with separate parts, since morphology and porosity can influence the adsorption capacity. The presence of an irregular surface, pores, and surface fractures of both the water hyacinth leaf and stem indicate the presence of micropores and a high surface area [46], which are fundamental and important characteristics of adsorbents [47]. Since these small spaces favor the entry of liquids and adsorption [48].…”