Examinando por Autor "Morales, Irene"

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Induction heating in nanoparticles impregnated zeolite
(MDPI, 2020-09-10) Morales, Irene; Muñoz, Marta; Costa, Catia; Alonso, Jose María; Silva, Joao Miguel; Multigner, Marta; Quijorna, Mario; Ribeiro, Maria do Rosário; de la Presa, Patricia
The ultra-stable Y (H-USY) zeolite is used as catalyst for the conversion of plastic feedstocks into high added value products through catalytic cracking technologies. However, the energy requirements associated with these processes are still high. On the other hand, induction heating by magnetic nanoparticles has been exploited for different applications such as cancer treatment by magnetic hyperthermia, improving of water electrolysis and many other heterogeneous catalytic processes. In this work, the heating efficiency of γ-Fe2O3 nanoparticle impregnated zeolites is investigated in order to determine the potential application of this system in catalytic reactions promoted by acid catalyst centers under inductive heating. The γ-Fe2O3 nanoparticle impregnated zeolite has been investigated by X-ray diffraction, electron microscopy, ammonia temperature program desorption (NH3-TPD), H2 absorption, thermogravimetry and dc and ac-magnetometry. It is observed that the diffusion of the magnetic nanoparticles in the pores of the zeolite is possible due to a combined micro and mesoporous structure and, even when fixed in a solid matrix, they are capable of releasing heat as efficiently as in a colloidal suspension. This opens up the possibility of exploring the application at higher temperatures.
Modulation of Crystallinity through Radiofrequency Electromagnetic Fields in PLLA/Magnetic Nanoparticles Composites: A Proof of Concept
(MDPI, 2021-07-31) Multigner, Marta; Morales, Irene; Muñoz, Marta; Bonache, Victoria; Giacomone, Fernando; de la Presa, Patricia; Benavente, Rosario; Torres, Belén; Mantovani, Diego; Rams, Joaquín
To modulate the properties of degradable implants from outside of the human body represents a major challenge in the field of biomaterials. Polylactic acid is one of the most used polymers in biomedical applications, but it tends to lose its mechanical properties too quickly during degradation. In the present study, a way to reinforce poly-L lactic acid (PLLA) with magnetic nanoparticles (MNPs) that have the capacity to heat under radiofrequency electromagnetic fields (EMF) is proposed. As mechanical and degradation properties are related to the crystallinity of PLLA, the aim of the work was to explore the possibility of modifying the structure of the polymer through the heating of the reinforcing MNPs by EMF within the biological limit range f H < 5 10^9 Am-1s-1. Composites were prepared by dispersing MNPs under sonication in a solution of PLLA. The heat released by the MNPs was monitored by an infrared camera and changes in the polymer were analyzed with differential scanning calorimetry and nanoindentation techniques. The crystallinity, hardness, and elastic modulus of nanocomposites increase with EMF treatment.