Remoção de cromo proveniente de efluentes sintéticos utilizando argilas organofílicas.

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.