Estudo da adsorção dos íons metálicos Cd2+ e Cu2+ por biossorção em leito fluidizado com a levedura Sacharomyces cerevisiae imobilizada com quitosana.

Abstract

Large proportions of heavy metal ions were released into the environment with waste and effluents contaminated by industrial activities. The heavy metal ions released into the environment causes greater environmental impacts than the pollution caused by pesticides, sulfur dioxide, nitrogen oxides and carbon monoxide, because the ions are not degraded. The biosorption process emerges as a cost-effective alternative for the removal of metal ions from contaminated through use of biomass as adsorbents. The focus of this work was to study the biosorption of metal ions of cadmium and copper in a fluidized bed column. We use as biosorbent yeast Saccharomyces cerevisiae immobilized on chitosan. The study was conducted biosorption separately for each ion using a 22 factorial design with three replications at the center point. The independent variables were the volumetric flow rate and initial concentration of solutions Cd2+ and Cu2+. The dependent variables analyzed were adsorbed amount and percentage of removal of ions. Through the breakthrough curves obtained by the testing biosorption of ions Cd2+ and Cu2+ in fluidized bed we found that there was no saturation of the bed in any operating condition studied. The breakthrough curves showed some stability after some time of adsorption, which led to the hypothesis of the simultaneous occurrence of other processes of removal of metal ions, probably a precipitation. Through statistical analysis for the biosorption of cadmium ion was found that the volumetric flow rate and initial concentration were statistically significant on the amount adsorbed, showing positive influence on this variable, while they showed no statistical significance on the percentage removal. Regarding the biosorption of copper ion, the volumetric flow rate was statistically significant on the adsorbed amount, increases with the increase of this variable. The initial concentration had a negative influence on the removal percentage. The model of the linear driving force (LDF) adequately represented the biosorption of ions Cd 2+ and Cu 2+ in fluidized bed.