Novel Magnetic Filters with Laccase-based nanoparticles for improving Congo Red decolorization in Bioreactors

Abstract

In this work, the design, manufacture and testing of five different magnetic biofilters based on magnetite, laccase magnetite and laccase magnetite with additional stuff is explored to increase the enzyme-based decolorization of dyes by Laccase-magnetite nanoparticles, improve the particle retention and promote the interaction of reagents. The laccase enzyme was covalently immobilized on amino-terminated silanized magnetite nanoparticles (Laccase-magnetite). The different configurations for the biofilters and the applied magnetic field was evaluated through three cycles of 50 mL. The Congo red dye was tested as a biotransformation model at concentrations of 60 mg/L. The optimal catalytic performance of the Laccase-magnetite was achieved in the pH 6. A better distribution of the particles on the filter was induced by the use of magnetic field with magnets and a grid or metal mesh, which promote greater durability of the nanocomposite in the filter and improving the treatment processes. Also, the overall dye removal efficiencies for this biofilters and the Laccasemagnetite were 5%, 13%, 17%, 23%, and 27% for the first cycle evaluated. The greatest loss of magnetite occurred in the case of the filter modified with magnets (57 mg) and the greatest loss of enzyme with respect to its concentration occurred in the first evaluated cycle of that treatment (456 µg). The use of permanent magnetic elements in the filters increased the half-life of the filter in a 3fold compared to the filters without enzymatic properties and 2-fold compared to filter with Laccasemagnetite. Taken together, our results indicate that the novel bioreactors introduced here have the potential to process wastewaters in continuous mode and that it is possible to improve the retention of this type of nanocomposites by making specific modifications and maintaining a permanent magnetic field.