Síntese de alumina a partir de resíduo de alumínio e avaliação do seu uso como adsorvente de corantes

Abstract

The aluminum foundry and aluminum parts industries produce large amounts of wastes. The inadequate disposal of these materials creates environmental problems. However, such waste can be used as raw material to obtain other materials with aggregate value and industrial interest as it is the case of alumina, alum, aluminum hydroxide, among others. This work discusses the use of aluminum metal waste as a source to obtain alumina and its application as an adsorbent in the removal of the dyes methylene blue, basic fuchsine and crystal violet. The synthesis of alumina was carried out by means of basic leaching with NaOH, employing HCl as precipitation agent. The morphology and structure of the alumina were investigated by FT-IR, XRD, SEM, TGA and EDX. The surface area determined by the BET method was 304.31 m2.g-1. Alumina showed potential as an adsorbent of the dyes in aqueous solution, and the maximum adsorption capacity experimentally determined was 57.8 mg.g-1 for methylene blue, 32.9 mg.g-1 for basic fuchsin and 31, 82 mg.g-1 for crystal violet at an initial concentration of 400 mg.L-1 for all dyes, the adsorptive capacity of the alumina synthesized from the residue was compared to the commercial one and it was superior in surface area and adsorption capacity, being 40 to 60% higher for the analyzed dyes, the thermal regeneration method of the adsorbent showed efficiency by three complete adsorption / desorption cycles. Toxicity tests were performed with the species Artemia salina and by means of germination of Lactuca sativa seeds, using the solutions of the dyes before and after treatment by adsorption. From the results obtained it was possible to verify that the alumina produced from aluminum waste has the potential to remove the dyes and can contribute to the reduction of possible toxic effects of these to the environment.