Biosorption of diethylketone and Cd using a Streptococcus equisimilis biofilm supported on vermiculite: kinetics and equilibrium studies

Abstract

This works aims to infer about the possible application of a supported biofilm on the simultaneous removal of a metal and a ketone from aqueous solutions and accordingly it describes two sets of experiments: cadmium and diethylketone, DEK, adsorption assays on vermiculite, the support, and cadmium and diethylketone biosorption assays on vermiculite covered by a S. equisimilis biofilm. Removal percentages between 60 % and 98 % were obtained by the vermiculite for initials concentrations of 3g/L of DEK. For Cd, the removal percentage ranged between 72 % and 78% for initials concentrations of 0.1 g/L of metal. Regarding the assays conducted with the S. equisimilis biofilm supported on vermiculite, the percentage of removed cadmium increases with the increase of the amount of vermiculite whereas DEK removal decreases (maximum removals of 86.16 % and 95.70 % for Cd and DEK, respectively). Adsorption kinetics for both pollutants follows the pseudo-second order model and equilibria are well described by the Freundlich and by the Dubinin-Radushkevich models for Cd and DEK respectively.