Efeito da temperatura de incubação na cinética e no equilíbrio da biossorção do cádmio por Sargassum filipendula

Abstract

The use of biomass for biosorption of heavy metals is well documented in the literature and several types of microbial species and seaweeds were already tested. Most of these works are conducted with dry biomass in order to prevent any undesirable metabolic response. Several literature reports suggest drying the biomass under mild conditions, such as sun-drying; on the other hand, several reports recommend the range from 313 K to 353 K to ensure complete inactivation of the biomass. The effect of sun-drying the biomass at 303 K and oven-drying at 333 K in Cd2+ ions remotion is here reported. Evaluation of results was based on the kinetics and uptake capacity of the metal by the seaweed Sargassum filipendula. Results indicated that the maximum metal uptake was not markedly reduced when oven-dried biomass was used, for cadmium concentrations ranging from 10.0 to 500.0 mg L-1. Kinetic tests performed indicated a better fit of the experimental data to the pseudo second order model, both for a dilute (10 mg L-1) and a concentrated solution (100 mg L-1). In both cases the effect of drying in an oven, at 333 K was slightly reflected in the uptake. Results were best represented by the Langmuir model in comparison to the Freundlich model. Thermogravimetric analysis confirmed that no structural damage due to drying at high temperatures was observed. Infrared spectra indicated no difference between the in natura and dried biomass. The effect of temperature on the metal uptake was significant in the range from 303 to 328 K, reflected in the cadmium uptake capacity