CABRAL, S. B.; http://lattes.cnpq.br/2849327266648308; CABRAL, Shâmia Borborema.
Abstract:
Serious enviromnental impacts consequence of the increasingly high rates
of industrial wastewater disposal containing large amounts of heavy metaIs along
with more strict enviromnental regulations have stimulate a myriad of promising
papers in this field. Particularly, chromium removal has called for important
researches due to its large use in processing plants throughput the globe. In
wastewater samples chromium has been found basically in the form trivalent (Cr3+)
and hexavalent chromium (Cr6+). Several kinds of solvents have been tested so as
to reduce the contamination of areas infested with such metaIs. This work
proposes the use of untreated and organophilic green-slit clays as adsorbents for
the treatment of synthetic solutions containing Cr3+.This work was carried out in
two stages: The first stage consisted of preparing an organophilic green-slit clay
sample by combining the Verde-Lodo clay untreated and quatemary ammonium
salt (cetyltrimethylammonium bromide). The composites were characterized by Xrays
Diffraction (XRD), Scanning Electron Microscopy (SEM), Differential Thermal
Analysis and Thermogravimetric Analysis (ATD / ATG), puffup Foster test and
adsorption capacity test. The results showed that the organophilic green-slit clay
was indeed obtained and that they were able to absorb the organic solvents tested.
The second part intended to assess the removal of Cr3+ in a solution sample using
the finite bath technique, and taking the untreated and organophilic green-slit clays
as adsorbents. Finite bath tests were conducted in accordance with a full 23
factorial design factorial with three experiments in central point using the Software
Minitab 13.0. The input variables consisted of stirring from 150 to 250 rpm; pH
ranging from 3.0 to 5.0; and initial concentration of chromium within 10 and 70
ppm. The output variables were chosen as removal of chromium (% Rem) and net
chromium removal (qeq). Statistical treatment of the resulting data showed that, in
general, the untreated green-slit clay performs better than the organophilic greenslit
clay in terms of chromium removal.