Adsorção e biodegradação de corantes de efluente têxtil utilizando partículas magnéticas e lacase

Abstract

Dyes are part of an important group of organic contaminants and cause impacts on aquatic environments and humans, when disposed of in effluents without proper treatment. The combination of physical chemical and biological methods to treat textile effluents, has emerged as a promising alternative. Among the biological treatment methods, biodegradation using laccase enzymes immobilized on magnetic supports is considered an environmentally friendly alternative, without sludge generation and which has shown efficiency. Magnetic iron oxide particles have advantages in enzymatic immobilization, such as low synthesis costs, easy separation, low toxicity and compatibility with biomaterials. In addition, magnetic particles have been reported as materials used in the adsorption of different pollutants, including dyes.In this context, the present work aimed to evaluate the adsorption of textile dyes on magnetic particles (Pmag) and compare with the simultaneous process of adsorption and biodegradation of dyes after the immobilization of laccase enzymes in the magnetic particles (Lac-Pmag). For this purpose, the laccase enzymes were produced by comparing the production from white rot fungi and the iron oxide Pmag were synthesized by the microwave heating and irradiation method. First, Pmag were tested for the adsorption capacity of Acid Blue 277 and Acid Black 172 dyes. Afterwards, the laccase enzymes of Trametes villosa were immobilized by the functionalization of particles using APTES ((3-aminopropyl) triethoxysilane) and glutaraldehyde. The results showed Pmag adsorption capacity for both dyes, with more than 95% removal efficiency when the lowest dye concentrations were used. In addition, the dye removal capacity was maintained in 6 consecutive adsorption and desorption cycles. The immobilization of laccase enzymes showed immobilization yield equal to 99.85 ± 0.18% and recovered activity of 46.18 ± 0.2%. In the simultaneous process of adsorption and biodegradation of dyes, the Lac-Pmag showed twice of removal efficiency at the highest concentrations of dyes, compared with Pmag. The Lac-Pmag dyes removal capacity was 52.72 ± 1.23 and 57.47 ± 2.38 mg g-1, for Acid Blue 277 and Acid Black 172, respectively. Thus, the results obtained presented promising alternatives for textile effluents treatment. The synthesized Pmag demonstrate efficiency in the adsorption of the textile dyes Acid Blue 277 and Acid Black 172. The Lac-Pmag demonstrated efficiency in the simultaneous process of adsorption and biodegradation in high concentrations of dyes, using a low amount of laccase enzymes in immobilization process, which makes the technology even more efficient and economical.