Sistemas bentonita sódica/quitosana obtidos por micro-ondas aplicados como adsorventes para corante aniônico

Abstract

Bionanocomposites based on the interaction between clay minerals and biopolymers have been applied in adsorption of pollutants and biological species. The present work describes the preparation and characterization of chitosan/bentonite nanocomposites and their application as adsorbents for 5R violet dye. The chitosan/bentonite nanocomposites were prepared in proportions of 50, 100, 200 and 300% of the cation exchange capacity of the clay mineral over microwave heating for 30 min at 323 K. The composites were characterized by elemental analysis of CHN, X-ray diffractometry, infrared absorption spectroscopy and thermal analysis. The characterization confirmed that the formation of intercalation hybrid and that their properties were improved for dye removal. In the adsorption studies parameters such as pH, adsorbent mass, contact time and initial dye concentration were evaluated. The obtained results showed that the prepared nanocomposites presented high adsorptive capacity, being able to reach 100% of the adsorption removal from 75 mg of adsorbent at pH 1.0. In relation to the contact time, the kinetic model of pseudosecond order was better fitted in relation to the adsorption kinetics of the violet dye 5 R. Data were adjusted to the Langmuir model, corroborating that the adsorptive process of the dye reached a monolayer. The hybrid materials synthesized in this work can be applied as good adsorbents for dye removal from aqueous solution.