Uso de biocompósito de nanofibras de PBAT eletrofiadas e bactérias do gênero bacillus anexadas para a biorremediação de corantes têxteis

Abstract

The textile industry cites dyes as one of its most frequent pollutants, which, if not properly treated, can cause water pollution and harm to living organisms, with detrimental health effects. In this context, the use of biocomposite materials, such as bacterial films attached to polymer fibers, presents itself as an environmentally friendly alternative for the bioremediation of these dyes. This study used PBAT (poly(butylene adipate-co-terephthalate)) biocomposites with Bacillus cereus group UELAsF2.2 bacteria to treat the textile dyes malachite green and methylene blue, as well as to study the morphological and chemical characteristics of the biocomposite and the polymer used. PBAT fibers were obtained by electrospinning. The polymer/bacteria biocomposite was formed by attaching the bacteria to the fiber surface through submersion of the fiber mat in a bacterial solution for 3 days. Bioremediation assays were performed using a Box-Behnken experimental design with factors of decolorization time (hours), fiber mass (mg), and dye concentration (mg/L), and responses of percentage of decolorization and enzymatic activity for laccase. Material reuse and bacterial growth were analyzed. Morphological analyses were performed using scanning electron microscopy (SEM). The results of the design indicated... Malachite green achieved a maximum discoloration of 98.1%, with parameter optimization at 53.6 h, 11 mg, and 16 mg/L, with validation tests showing very similar discoloration. Methylene blue achieved a maximum discoloration of 99.2%, with parameter optimization at 17.3 h, 8.4 mg, and 15.2 mg/L, with validation tests showing 96% discoloration. The biocomposite could be used for 5 cycles without appreciable loss of discoloration capacity, which is the greatest advantage of using this type of material. SEM revealed the presence of bacterial cells on the fiber surface, as well as the presence of chemical elements from the dyes after contact with the biocomposite. FTIR confirmed the presence of typical biofilm chemical groups after bacterial attachment, such as hydroxyls, and chemical groups from the dyes, showing tertiary amine stretching and the presence of stretching. typical of benzene ring linkages. It is concluded that the biocomposites formed have the capacity for bioremediation of the two dyes studied, with emphasis on the ability of the material to be used for several bioremediation cycles.