| dc.description | The adsorption process has been used as an efficient method for the removal
of metallic ions from effluents. In this work, it is presented the studies to evaluate
the adsorption capacity of Co in kaolinite, a low cost adsorbent, aiming at the removal
of this ion from aqueous solutions. The specific surface area (S) was analyzed
in 25 samples prepared in different ways: kaolinite, bentonite and activated carbon
and, mixtures of kaolinite-bentonite and kaolinite-activated carbon. These mixtures
were prepared by adding to kaolinite 10, 20, 30, 40 or 50% of activated charcoal
or bentonite. Samples of kaolinite-activated charcoal mixture and raw kaolinite were
also calcined at 600 and 1000 C for 4h. The adsorption parameters investigated for
these adsorbents were: contact time, pH, solute initial concentration, ionic competition
and ionic strength. It was found that the optimized contact time and pH, for the
purpose of this work, were 30 min and pH 6. Under these conditions the cobalt ion
removal efficiency was greater than 80%. It was verified that the presence of Cr and
Zn ions, as well as the increase in ionic strength caused a decrease in the adsorption
capacity of Co in the adsorbent mixture. The Langmuir and Freundlich isotherms
presented R2 equal to 0.906 and 0.597, respectively. The parameters determined by
these isotherms indicated a spontaneous process, i.e., energetically favorable, for the
adsorption of Co under the conditions that this work was carried out. | |
