Influência da ativação térmica e ácida da caulinita na adsorção do corante azul de metileno

Abstract

The progress on urban and industrial development brings with it some problems, among the most worrying is the water and atmospheric pollution. Industries produce waste that, if not being treated before sent to the environment, can cause serious damage to nature. Dyes are one of those pollutants that damage aquatic organisms, as they difficult the passage of light, which hinders plant photosynthesis, in addition to affecting the life of aquatic animals. Adsorbents have been used to retain these dyes, an option of this group are clay minerals that are abundantly found in nature. In this work, a heat treatment was carried out at 750°C for 3 hours, followed by an acid treatment with 6M hydrochloric acid in a kaolinite sample, in order to increase the porosity, surface area and adsorption capacity of the material, in addition to furthermore, the influence of pH on the adsorption performance of the cationic dye was also analyzed. Through XRD, XRF, SEM and UV-Vis spectroscopy analyses, it was possible to observe the changes caused by the treatments in the composition and microstructure of kaolinite, which changed from a crystalline structure to an amorphous phase with a considerable decrease in the percentage of aluminum presente in the material. The morphological changes were also observed. The adsorption of methylene blue dye on kaolinite increased after treatments, from pure kaolinite with a percentage of 46.7% of adsorption to activated kaolinite which resulted in an adsorption of 66.5% of the dye, the increase to a pH 10 (basic) improved the adsorption percentage to 97.9% in activated kaolinite. These values show that activated kaolinite has a great potential for applications as an adsorbent, removing most of the methylene blue dye from water.