Development of magnetic nanobiocatalysts for environmental remediation

Abstract

The chemistry can be considered as a key science for a sustainable development, working on the processes lead to produce less waste, decreasing toxic effluents generation. This new path laid out by the chemistry is denominated "Green Chemistry". Among the principles governing the Green Chemistry, the catalytic processes are vital importance, therefore, the objective of this research includes the development of magnetic nanobiocatalysts, which have a potential for phenolic remediation, toxic compounds present in wastewater. The biocatalysts were obtained immobilizing oxidoreductive enzymes on magnetic nanoparticles (NPs) of iron oxide (δ -FeOOH). Soybean peroxidase (SP) obtained from soybean hulls, an agro industrial residue, and horseradish peroxidase (HRP) commercial peroxidase obtained from Sigma-Aldrich were the peroxidases utilized in the processes. Co-precipitation was the method used to synthesize the NPs. For generating interest groups, the NPs were submitted to chemical functionalization. Soybean peroxidase was immobilized on functionalized NPs, whereas the HRP immobilization was investigated using the magnetic particles non-functionalized as support. With the variation of important immobilization factors (enzyme ratio / NPs, pH, temperature, and time) a statistical design of experiments (DOE) was performed to optimize the immobilization process. The Response Surface Methodology (MSR) was a graphical technique that allowed to explore the influences of these factors in the process. The structures of the materials were evaluated by X-ray diffractometry (XRD), Fourier Transform Infrared Spectroscopy (IVTF) and Scanning Electron Microscopy (SEM). To investigate the catalytic potential of the developed nanobiocatalysts, the oxidation of the pollutant ferulic acid (FA), a model molecule of lignin, was evaluated. The results have shown that the SP immobilization on functionalized NPs was effective. Removing 93% of AF, with recycling up to 10 cycles. HRP immobilized from optimized conditions resulted in a magnetic biocatalyst capable of removing 82% of FA. Obtaining magnetic catalysts developed using plant enzymes as well as their residues has proved to be an alternative that combines biocatalytic, and magnetic properties in a single material, overcoming some drawbacks of conventional catalytic processes related to the recovery, and regeneration of the catalyst.