Engineering Iron Oxide Nanocatalysts by a Microwave-Assisted Polyol Method for the Magnetically Induced Degradation of Organic Pollutants.

Alvaro Gallo-Cordova,Jesús G Ovejero,Sabino Veintemillas-Verdaguer,María Del Puerto Morales,Eva Mazarío,Pedro Tartaj

doi:10.3390/nano11041052

Abstract

Advanced oxidation processes constitute a promising alternative for the treatment of wastewater containing organic pollutants. Still, the lack of cost-effective processes has hampered the widespread use of these methodologies. Iron oxide magnetic nanoparticles stand as a great alternative since they can be engineered by different reproducible and scalable methods. The present study consists of the synthesis of single-core and multicore magnetic iron oxide nanoparticles by the microwave-assisted polyol method and their use as self-heating catalysts for the degradation of an anionic (acid orange 8) and a cationic dye (methylene blue). Decolorization of these dyes was successfully improved by subjecting the catalyst to an alternating magnetic field (AMF, 16 kA/m, 200 kHz). The sudden temperature increase at the surface of the catalyst led to an intensification of 10% in the decolorization yields using 1 g/L of catalyst, 0.3 M H2O2 and 500 ppm of dye. Full decolorization was achieved at 90 °C, but iron leaching (40 ppm) was detected at this temperature leading to a homogeneous Fenton process. Multicore nanoparticles showed higher degradation rates and 100% efficiencies in four reusability cycles under the AMF. The improvement of this process with AMF is a step forward into more sustainable remediation techniques.

Highlights

Nanotechnology can be considered a “small” solution for many big problems, bringing novel benefits in terms of products and processes
The microwave-assisted synthesis of magnetic iron oxide nanoparticles (MIONPs) in polyol media has been explored for the preparation of single-core and multicore iron oxide nanoparticles
Some experimental parameters were kept constant as they were already optimized in previous works [28,29]

Summary

Introduction

Nanotechnology can be considered a “small” solution for many big problems, bringing novel benefits in terms of products and processes. There are already a wide range of studies on new nanomaterials that are transforming the available technology in areas as important as medicine (nanomedicine, theragnosis, etc.) and sustainable development (clean energy, environmental remediation, etc.) [1]. Magnetic iron oxide nanoparticles (MIONPs) stand out with their unique magnetic properties, low environmental impact, high biocompatibility, and wide versatility in technological fields such as wastewater treatment, catalysis, biomedicine, etc. MIONPs have been used for the removal and degradation of different contaminants in either waste or drinking water with outstanding results [5]. This class of magnetic nanoparticles presents specific features like their large surface-to-volume ratio and high colloidal stability, a good magnetic response, and a powerful heating capacity under alternating magnetic fields [4].

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Conclusion