Estudo do processo de dessorção de cromo hexavalente presente em algas marinhas provenientes do processo de biossorção

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

Chromium plays an important role in industries involved with electroplating, polish of metals, tannings, paints, pigments and wood preservation. It is considered a major poluter of the natural environrnent. This metal occurs in many oxidation states, but the most commom are the trivalent (Cr3) and hexavalent (Cr6), being the last one carciogenic and mutagenic. The conventional methods used to remotion of heavy metaIs such as chemical precipitation and chemical oxitation or reduction are not always efficient. This stimulates research oriented to the development of altemative technologies enabling more adquate processes of remotion. In the last years, an expressive research effort has been accomplished towards the utilization of microorganismslbiomass to remotion of heavy metais ITom efluents by a process called biosorption. Among the biomass, the marine algaes, which exhibit interesting characterists such as abundance and strutural richness can be used as solid retainers of heavy metal, substituting the conventional resines. The advantages of this process are removal efficiency and possibilities of reuse of the biomass through the desorption of metalic ions. This workpresents a study of the desorption process of hexavalent chromium with the marine algaes (Sargassum sp), obtained ftom the process of biosorption. The study was rea1ized through the factorial planning 23 using three eluents: HCI, HzSO4 and EDT A. Three important factors to the process were analyzed: Eluent concentration, S/L relation (biosovent mass divided by eluent volume) and process time. The result of statistical analysis ITom the trials realized, for three eluents used, showed that the three analyzed variables were statistically significant, and the obtained models for the chromium desorption yielded a satisfactory fitting to the observed values in the trials. Using the response surface methodology, which is a technique of optimization based on the use of factorial design, it made possible the identification of the range of values for the process variables for a higher desorption of the adsorbed chromium. This range of values was used to optimize the process, giving maximum desorption capacity for the eluent EDT A of 50 mg/g (mg of chromium per g ofbiosorbent), reaching 52% ofthe desorption

ASSUNTO(S)

cromo biotecnologia alga marinha adsorção

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