C. Pereira, M. Rocha, C. Fernandes, S.L.H. Rebelo, C. Freire
magnetic nanoparticles, nanocatalysis, epoxidation, dye degradation, 4-nitrophenol reduction
In the last decades, the global concern for environment protection boosted the development of cost-effective eco-friendly catalytic processes. Magnetic nanoparticles emerged as a new generation of catalysts or catalyst supports owing to their nanosize, easy dispersion in several solvents and, more remarkably, their efficient recovery from the reaction medium by magnetic separation. This process prevents mass losses associated with traditional separation techniques and avoids the use of additional solvents, providing a greener alternative to heterogeneous catalysts. In this work we will provide an overview of our recent breakthroughs in the design of magnetically recyclable nanocatalysts. Silica-coated magnetic nanoparticles were used as supports for the immobilization of complexes with high catalytic efficiency in oxidation reactions for the production of valuable building blocks for organic synthesis. Superparamagnetic nanoferrites (MFe2O4, M=Co,Fe,Mn) with fine-tuned properties were produced by a new coprecipitation route and tested as nanocatalysts in the degradation of methylene blue dye (Fenton reaction). Finally, mesoporous silica-coated MnFe2O4 nanoparticles functionalized with amines and thiols were used as supports for gold nanoparticles. The nanocatalyst was tested in the 4-nitrophenol reduction, used in the production of pesticides and dyes and commonly found in resulting wastewaters. In all cases, high catalytic performances were achieved.