Estudo de equilíbrio da sorção do azul de metileno em resíduos de crustáceos

Abstract

Due to the large amount of residues from crustaceans such as crab, soft crab, oyster and guaiamum generated in the coast of Sergipe state, the proper and efficient use of these residues was sought. With accelerated growth and rapid industrialization, a large amount of effluent containing dyes is being generated, among which is methylene blue, a dye widely used in the textile industry, classified as a basic dye, having heterocyclic aromatic molecular structure and being considered, as cited by Oliveira (2012), a model compound for the study of contaminant removal in aqueous solutions, widely used in adsorption tests. The pollution of water bodies with this dye causes, besides visual pollution, changes in biological cycles, making it necessary to implement methods that promote the reduction of contamination. One of the processes for the treatment of these effluents is adsorption, a phenomenon in which it consists in removing contaminants from the use of an adsorbing agent, being a low cost and effective process. Therefore, this work aimed to carry out experiments with crustacean residues, using them as adsorbent agent, thus evaluating the removal capacity of methylene blue in effluents. Methylene blue sorption tests on crab, crab, guaiamum and oyster biomass were performed in batches and the sorption experimental results were adjusted by Langmuir, Freundlich and Toth isotherm models. The biomasses were characterized by morphological aspects (MEV) and functional groups (FTIR). The Toth isotherm model presented the best fit for all biomasses consistent with heterogeneous aspects of the biomass surfaces revealed by SEM. The max values obtained by the Toth model were as follows: 66.49 mg/g for guaiamum, 17.30 mg/g for oyster, 12.01 mg/g for soft crab and 10.54 mg/g for crab. the crab, thus demonstrating that guaiamum is the best adsorbent among other crustacean residues. The FTIR analyzes revealed that the chitin hydroxyl (OH-) of chitin and carbonate (CO3-2) of calcite (CaCO3), present in biomass, are groups responsible for the removal of methylene blue.