Maryam Abdolrahimi

Thermo‐magneto‐responsive soft materials, composed of polymer matrices embedded with magnetic particles, are promising for smart systems capable of controlled shape morphing under alternating magnetic fields (AMFs) via localized heating. This study examines how synthesis method (solvent‐assisted polymer dissolution vs. temperature‐induced softening), magnetic filler type (FeNi, γ‐Fe ₂ O ₃ , CoFe ₂ O ₄ ), and loading percentage (10–30 wt.%) influence the self‐heating performance of polylactic acid (PLA) nanocomposites, a biocompatible polymer widely used in fused filament fabrication (FFF). All formulations retain the magnetic properties of bare particles, with saturation magnetization increasing proportionally to filler content. FeNi‐ and γ‐Fe ₂ O ₃ ‐based PLA nanocomposites exhibit the highest temperature increase under AMFs maintained within physiologically tolerable levels for potential biomedical use. At 20 wt.% loading, γ‐Fe ₂ O ₃ /PLA demonstrates better heating efficiency, whereas FeNi/PLA exhibits superior temperature increases at higher filler concentrations. To demonstrate practical feasibility, FeNi/PLA filaments were successfully extruded and processed via FFF to produce structures specifically designed for controlled shape morphing. Shape‐recovery experiments under AMFs confirm that the printed object can be reliably actuated, providing proof‐of‐concept validation for the functional application of these composites. Overall, these findings provide practical guidelines for the design of thermo‐magneto‐responsive PLA nanocomposites by balancing heating efficiency, FFF processability, and human‐safe AMF operating conditions.

This study explores the applicability of magnetic zeolites from industrial waste for the removal of emerging water contaminants and their recovery by ultrasound (UsAE), microwave (MwAE), and magnetic hyperthermia (MhAE) assisted extraction.

Using the thermal decomposition method, we have prepared monodisperse cobalt ferrite nanoparticles (CoFe2O4 NPs) of average size ~12 nm. A ligand exchange process was carried out to replace the post-synthesis hydrophobic oleic acid (OA) coating with hydrophilic polyacrylic acid (PAA). X-ray photoelectron spectroscopy (XPS) confirmed the successful ligand exchange process, and zeta potential measurements validated long-term stability in water in a broad pH range due to a significant negative charge of PPA-coated samples (−30 mV). Importantly, the magnetic behavior remains essentially unchanged with saturation magnetization (~65 A · m2/kg) and coercivity (~80 mT) at 300 K for samples before and after ligand exchange. In addition, δm plots confirmed moderate dipoledipole interparticle magnetic interactions, which remained consistent after surface modification. These findings demonstrate that surface functionalization with PAA preserves the key magnetic features of CoFe2O4 NPs, while providing stability in aqueous media for further biomedical applications.

Volcanic ashes from Mount Etna are hydrothermally transformed into magnetic zeolites. Combined XAS and magnetometry reveal Fe phase transitions from olivine to magnetite-like and hematite phases, tuning oxidation states and magnetic responses.

Biodegradable polymer matrices, PCL and PBSA were used to fabricate magnetic composites with recycled NdFeB and rare earth-free lab-synthesized ferrite fillers (SrFe₁₂O₁₉ and SrFe₁₂O₁₉–CoFe₂O₄) across a wide filling range (1–90%).

Adsorption has emerged as a promising method for removing polyphenols in water remediation. This work explores chlorogenic acid (CGA) adsorption on zeolite-based magnetic nanocomposites synthesized from rice husk waste. In particular, enhanced adsorbing materials were attained using a hydrothermal zeolite precursor (Z18) synthesized from rice husk and possessing a remarkable specific surface area (217.69 m² g⁻¹). A composite material was prepared by immobilizing magnetic copper ferrite on Z18 (Z18:CuFe₂O₄) to recover the zeolite adsorbent. In addition, Z18 was modified (Z18 M) with a mixture of 3-aminopropyltriethoxysilane (APTES) and trimethylchlorosilane (TMCS) to improve the affinity towards organic compounds in the final nanocomposite system (Z18 M:CuFe₂O₄). While the unmodified composite demonstrated inconsequential CGA removal rates, Z18 M:CuFe₂O₄ could adsorb 89.35% of CGA within the first hour of operation. Z18 M:CuFe₂O₄ showed no toxicity for seed germination and achieved a mass recovery of 85% (due to a saturation magnetization of 4.1 emu g⁻¹) when an external magnetic field was applied. These results suggest that adsorbing magnetic nanocomposites are amenable to CGA polyphenol removal from wastewater. Furthermore, the reuse, revalorization, and conversion into value-added materials of agro-industrial waste may allow the opportunity to implement sustainability and work towards a circular economy.

The present work aimed at decorating halloysite nanotubes (HNT) with magnetic Fe₃O₄ nanoparticles through different synthetic routes (co-precipitation, hydrothermal, and sol-gel) to test the efficiency of three magnetic composites (HNT/Fe₃O₄) to remove the antibiotic ofloxacin (OFL) from waters. The chemical–physical features of the obtained materials were characterized through the application of diverse techniques (XRPD, FT-IR spectroscopy, SEM, EDS, and TEM microscopy, thermogravimetric analysis, and magnetization measurements), while ecotoxicity was assessed through a standard test on the freshwater organism Daphnia magna. Independently of the synthesis procedure, the magnetic composites were successfully obtained. The Fe₃O₄ is nanometric (about 10 nm) and the weight percentage is sample-dependent. It decorates the HNT’s surface and also forms aggregates linking the nanotubes in Fe₃O₄-rich samples. Thermodynamic and kinetic experiments showed different adsorption capacities of OFL, ranging from 23 to 45 mg g⁻¹. The kinetic process occurred within a few minutes, independently of the composite. The capability of the three HNT/Fe₃O₄ in removing the OFL was confirmed under realistic conditions, when OFL was added to tap, river, and effluent waters at µg L⁻¹ concentration. No acute toxicity of the composites was observed on freshwater organisms. Despite the good results obtained for all the composites, the sample by co-precipitation is the most performant as it: (i) is easily magnetically separated from the media after the use; (ii) does not undergo any degradation after three adsorption cycles; (iii) is synthetized through a low-cost procedure. These features make this material an excellent candidate for removal of OFL from water.

In this work, red mud (RM) and spinel iron oxide nanoparticles (SPIONs) were added to pure silica/alumina sources (SAs) and fly ash (FA) with the aim of synthesizing and investigating the magnetic behavior of different zeolites. SAs were used to synthesize zeolite with LTA topology (zeolite A) with the addition of both red mud and spinel iron oxide nanoparticles. FA and RM were mixed to synthesize sodalite whereas only FA with the addition of SPIONs was used to form zeolite with FAU-topology (zeolite X). All the synthetic products showed magnetic properties. However, zeolites with spinel iron oxide nanoparticles (zeolites A and X) showed ferromagnetic-like behavior. Sodalite was characterized by a reduction in saturation magnetization, whereas zeolite A with red mud displayed antiferromagnetic behavior. For the first time, all the synthetic products were tested for polluted water remediation by a persistent emerging contaminant, ofloxacin (OFL) antibiotic. The four zeolite types showed good adsorption affinity towards OFL under actual conditions (tap water, natural pH). All materials were also tested for OFL removal in real waters spiked with OFL 10 µg L⁻¹. Satisfactory recoveries (90–92% in tap water, 83–87% in river water) were obtained for the two zeolites synthesized from industrial waste materials.

The design of novel multifunctional materials based on nanoparticles requires tuning of their magnetic properties, which are strongly dependent on the surface structure. The organic coating represents a unique tool to significantly modify the surface structure trough the bonds between the ligands of the organic molecule and the surface metal atoms. This work presents a critical overview of the effects of the organic coating on the magnetic properties of nanoparticles trough a selection of papers focused on different approaches to control the surface structure and the morphology of nanoparticles’ assemblies.