Caracterização e aplicação das cinzas de caldeira em testes de adsorção dos corantes coriacide black e reactive yellow da indústria coureira

Abstract

The leather industry has great economic importance in countries such as Brazil and India, however, the presence of this type of industry brings with it the generation of effluents with high toxicity and a high organic load. Faced with this problem, and knowing the usefulness of ash as an adsorbent material, the present work evaluated the ability of ash to adsorb the dyes reactive yellow and coriacide black. This research presents the results of the characterization of bottom ash from a local industry and the evaluation of the adsorption capacity of the dyes used in the leather industry, coriacide black and reactive yellow, in them. The results of the ash characterization indicate the presence of particles of varied compositions with sizes of approximately 10 μm. They can be divided into three main groups, of which 39.7% are silicate particles, 35.35% are metal oxides and 24.21% are carbon. For the adsorption tests, the ash was first washed with distilled water and dried in an oven. Subsequently, a portion was washed with 1 mol/L sodium hydroxide solution. The dye solutions were prepared at natural pH and in an acidic medium with pH between 2 and 3, using 0.1 mol/L hydrochloric acid. 30 g of ash were placed in the dye solutions that were kept under stirring. Aliquots of the solutions were removed every 30 min to evaluate the adsorption capacity of the ashes by means of absorbance using a UV-Vis spectrophotometer, at a wavelength of 598 nm for coriacide black and 410 nm for reactive yellow. The results were very promising for the raw boiler ashes, reaching 100% adsorption of both dyes in acidic pH solution