Treatment of Wastewater, Phenols and Dyes Using Novel Magnetic Torus Microreactors and Laccase Immobilized on Magnetite Nanoparticles

Abstract

In this work, the design, manufacture, and testing of three different magnetic microreactors based on torus geometries (i.e., one-loop, two-horizontal-loop, and two-vertical-loop) is explored to increase the enzyme-based transformation of dyes by laccase bio-nanocomposites, improve the particle suspension, and promote the interaction of reagents. The laccase enzyme was covalently immobilized on amino-terminated silanized magnetite nanoparticles (laccase-magnetite). The optimal configuration for the torus microreactor and the applied magnetic field was evaluated in silico with the aid of the CFD and particle tracing modules of Comsol Multiphysics®. Eriochrome Black T (EBt) dye was tested as a biotransformation model at three different concentrations, i.e., 5 mg/L, 10 mg/L, and 20 mg/L. Phenol oxidation/removal was evaluated on artificial wastewater and real wastewater. The optimal catalytic performance of the bionanocomposite was achieved in the range of pH 4 to 4.5. A parabolic movement on the particles along the microchannels was induced by the magnetic field, which led to breaking the stability of the laminar flow and improving the mixing processes. Based on the simulation and experiments conducted with the three geometries, the two-vertical-loop microreactor demonstrated a better performance mainly due to larger dead zones and a longer residence time. Additionally, the overall dye removal efficiencies for this microreactor and the laccase-magnetite bionanocomposite were 98.05%, 93.87%, and 92.74% for the three evaluated concentrations. The maximum phenol oxidation with the laccase-magnetite treatment at low concentration for the artificial wastewater was 79.89%, while its phenol removal efficiency for a large volume of real wastewater was 17.86%. Treatments with real wastewater were carried out with a larger volume, equivalent to 200 biotransformation (oxidation) operating cycles of those carried out with dyes or phenol. Taken together, our results indicate that the novel microreactors introduced here have the potential to process wastewaters rich in contaminant dyes in continuous mode with efficiencies that are attractive for a potential large-scale operation. In this regard, future work will focus on finding the requirements for scaling-up the processes and evaluating the involved environmental impact indexes, economic performance, and different device geometries and processing schemes.

Prospects for Combined Applications of Nanostructured Catalysts and Biocatalysts for Elimination of Hydrocarbon Pollutants

“…The use of the obtained bionanocomposites (bioNComs = "laccasemagnetite") enabled the treatment of artificial and real wastewaters with the extraction of the dye Eriochrome Black T and phenol. Optimal catalytic characteristics were achieved in the media with pH 4-4.5 [86]. Only laccase and other oxidoreductases (tyrosinase and horseradish peroxidase) were considered for phenol degradation [87].…”

“…Only laccase and other oxidoreductases (tyrosinase and horseradish peroxidase) were considered for phenol degradation [87]. It is more expedient to consider the use of enzymes in the immobilized form [88], including as a component of bioNComs [86].…”

Magnetic Torus Microreactor as a Novel Device for Sample Treatment via Solid-Phase Microextraction Coupled to Graphite Furnace Atomic Absorption Spectroscopy: A Route for Arsenic Pre-Concentration

“…The convex alignment of semicircular elements produces a flow pattern that improves mixing. One channel geometry that falls in such category and that has been recently considered to enable applications in wastewater treatment is the toroidal [ 21 ]. In this regard, a torus microreactor exhibits a “coupled mobility matrix” that offers a resistance to flow throughout the translational propulsion of the geometry, around a central rotation point [ 22 , 23 ].…”

Optimization of photocatalytic degradation of biochemical oxygen demand from textile industry effluent using copper oxide nanoparticles by response surface methodology

“…Nanoparticles are particles between 1 and 100 nm in diameter that have recently contributed to the development of science, especially in the field of wastewater treatment 17,18 . Several studies have used nanoparticles to remove contaminants from aqueous solutions, like a study by Li et al to adsorption and electrochemical behavior investigation of methyl blue onto magnetic nickel‐magnesium ferrites nanoparticles, 19 by Xu et al to methyl blue adsorption by Magnetic nickel ferrite (NiFe 2 O 4 ) nanorods, 20 by Yu et al to adsorption of Methyl Blue onto Magnetic NixMgyZn (1−x−y) Fe 2 O 4 Nanoparticles, 21 by Peñaranda et al to treatment of wastewater, phenols and dyes on Magnetite Nanoparticles, 22 by Shahabuddin et al to degradation of carcinogenic dyes using 2D boron nitride doped polyaniline hybrid nanocomposites for photocatalytic, 23 by Shahabuddin et al to methylene blue degradation under visible light using SrTiO 3 Nanocube‐Doped Polyaniline Nanocomposites, 24 by Shahabuddin et al to methylene blue degradation using chitosan grafted‐polyaniline/Co 3 O 4 nanocube nanocomposites 25 and by Shahabuddin et al to methyl orange adsorption using Co 3 O 4 nanocube‐doped polyaniline nanocomposites 26 . Nanotechnology provides a media for effective removal of contaminants and pathogenic microorganisms in water and wastewater 27,28 .…”