In this investigation, we synthesized magnetic nanoparticles coated with silica and functionalized with p-sulfonic acid calix[4]arene (CX4), to be used as heterogeneous acid catalysts for acetal synthesis. We evaluated the catalytic efficiency of these nanoparticles for acetal synthesis using various aldehydes and glycerol under microwave irradiation at atmospheric pressure, with and without solvents. Two distinct synthesis methods, Pechini (Fe/pch/Si/CX4) and precipitation (Fe/ppt/Si/CX4), resulted in variations in the physical and chemical properties of the solids produced. Structural characterization involved thermogravimetry analysis (TG), X-ray diffraction (XRD), Mössbauer spectroscopy, vibrating sample magnetometry, scanning and transmission electron microscopy (SEM and TEM), infrared spectroscopy (FTIR), and titration for acidic site quantification. Fe/ppt/Si/CX4 exhibited goethite phases, while Fe/pch/Si/CX4 showed a substantial proportion of maghemite. Both catalysts demonstrated significant activity in acetal synthesis, achieving approximately 80% conversion without solvents. Notably, Fe/ppt/Si/CX4 exhibited higher activity likely due to its structural properties and crystalline phases of the synthesized iron oxide, suggesting a composition difference from the Pechini method. investigation psulfonic p sulfonic calix4arene calixarene calix 4 arene CX4, CX4 CX , (CX4) pressure solvents methods FepchSiCX4 FepchSiCX Fe pch Si (Fe/pch/Si/CX4 Fe/ppt/Si/CX4, FepptSiCX4 FepptSiCX ppt (Fe/ppt/Si/CX4) produced TG, TG (TG) Xray X ray XRD, XRD (XRD) magnetometry SEM TEM, TEM TEM) FTIR, FTIR (FTIR) quantification Fe/ppt/Si/CX Fe/pch/Si/CX maghemite 80 Notably oxide method (CX4 (Fe/pch/Si/CX (Fe/ppt/Si/CX4 (TG (XRD (FTIR 8 (CX (Fe/ppt/Si/CX

The generation of clean, zero-carbon, and renewable energy is a challenge for the development of a sustainable and egalitarian society. Hydrogen gas can be produced by water electrolysis and has been claimed as the most promising option to replace fossil fuels. The oxygen evolution reaction (OER) is the most energetically demanding step of the water splitting and requires the use of electrocatalysts to overcome the kinetic barrier. Iron oxide nanomaterials have been emerging as a low-cost and Earth-abundant OER electrocatalysts. The synthesis of iron oxide assisted by plant extract is an eco-friendly approach to obtain nanomaterials with unique properties. Herein, we investigated iron oxide synthesized with the assistance of Camellia sinensis extract, under different experimental conditions towards oxygen evolution reaction electrocatalysis. Pure phases of iron oxide were obtained, ferrihydrite and maghemite showed overpotentials of 460 and 480 mV at a current density of 10 mA cm–2, respectively. After calcination, hematite was formed and the overpotential was raised to 610 and 810 m V, respectively. The lower overpotential of the amorphous materials could be related to the lower electron transfer resistance and faster reaction rate. On the other hand, the calcinated materials presented higher specific activity, stability and higher Faradaic efficiency. clean zerocarbon, zerocarbon zero carbon, carbon zero-carbon society fuels (OER barrier lowcost low cost Earthabundant Earth abundant ecofriendly eco friendly properties Herein electrocatalysis obtained 46 48 1 cm2 cm 2 cm–2 respectively calcination 61 81 V rate hand activity efficiency 4 cm– 6 8

Abstract Iron oxide nanoparticles (FeO-NPs) are widely used in scientific and technological fields. Environmental concerns have been raised about residual FeO-NPs levels as their toxicity and bioaccumulative potential are not well understood. Oreochromis niloticus were exposed to nanoparticles of γ-Fe2O3 and Fe3O4. Micro-CT 3D image and grayscale graphic assessments revealed the accumulation of radiopaque material in the digestive tract of fish exposed to FeO-NPs. Histological analysis showed the presence of such NPs in the hepatopancreas, gills, kidneys, and muscles. No genotoxicity occurred, through micronucleus test and comet assay in peripheral erythrocytes. Body clearance was confirmed by iron-content reduction in organisms exposed to FeO-NPs after recovery period. No tissue injuries were observed in the exposed animals which may be attributed to the absence or low toxicity of iron oxide nanoparticles under the study conditions. O. niloticus showed tolerance to sublethal exposures to FeO-NPs. FeONPs FeO (FeO-NPs fields understood γFe2O3 γFeO γ Fe2O3 Fe O γ-Fe2O Fe3O4 MicroCT Micro CT D FeONPs. NPs. hepatopancreas gills kidneys muscles occurred erythrocytes ironcontent content period conditions γFe γFe2O Fe2O Fe3O

As nanopartículas (NPs) à base de óxido de ferro, como magnetita e maguemita, têm grande destaque em diversas áreas da ciência, inclusive na medicina. Há décadas, elas são usadas na reposição de ferro para pacientes com anemia, como agentes de contraste em ressonância magnética (MRI – “Magnetic Resonance Imaging”), na entrega de agentes terapêuticos mediada ou não por gradiente de campo magnético, em terapias térmicas foto e magnetoestimuladas, entre outras. Neste artigo, apresentamos suas propriedades magnéticas. Discutimos de forma breve seu ordenamento ferrimagnético, a importância da anisotropia magnética e sua relação com a histerese magnética (modelo de Stoner-Wohlfarth) e o regime superparamagnético. As diferenças entre superparamagnetismo e paramagnetismo são enfatizadas, além da importância da estabilidade coloidal dessas nanoestruturas para aplicações biomédicas. Finalmente, diversas aplicações biomédicas são discutidas, entre elas hipertermia magnética, terapia fototérmica, imunoterapia e uma nova técnica de imagem com potencial clínico, conhecida como “Magnetic Particle Imaging” (MPI). NPs (NPs maguemita ciência medicina décadas anemia MRI Magnetic Imaging, Imaging , Imaging”) magnético magnetoestimuladas outras artigo magnéticas ferrimagnético modelo StonerWohlfarth Stoner Wohlfarth Stoner-Wohlfarth superparamagnético enfatizadas Finalmente discutidas fototérmica clínico MPI. MPI . (MPI) (MPI

Iron oxide-based nanoparticles (NPs), such as magnetite and maghemite, are highly prominent in various scientific fields, including medicine. For decades, they have been used for iron supplementation in patients with anemia, as contrast agents in magnetic resonance imaging (MRI), in the delivery of therapeutic agents mediated or not by magnetic field gradients, and in photo- and magneto-stimulated thermal therapies, among other applications. In this article, we present their magnetic properties. We briefly discuss their ferrimagnetic ordering, the importance of magnetic anisotropy and its relation to magnetic hysteresis (Stoner-Wohlfarth model), and the superparamagnetic regime. The differences between superparamagnetism and paramagnetism are emphasized, as well as the importance of the colloidal stability of these nanostructures for biomedical applications. Finally, various biomedical applications are discussed, including magnetic hyperthermia, photothermal therapy, immunotherapy, and a new imaging technique with clinical potential known as Magnetic Particle Imaging (MPI). oxidebased oxide based NPs, NPs , (NPs) maghemite fields medicine decades anemia MRI, MRI (MRI) gradients photo magnetostimulated magneto stimulated therapies article properties ordering StonerWohlfarth Stoner Wohlfarth model, model model) regime emphasized Finally discussed hyperthermia therapy immunotherapy MPI. MPI . (MPI) (NPs (MRI (MPI

Abstract Nanocomposites formed of natural-origin iron oxide nanoparticles (magnetite and maghemite, Fe3O4 and γ-Fe2O3, respectively) were processed using the sol-gel process into core-shell structures containing silica and samarium to investigate their potential for applications in cancer treatments combining hyperthermia and brachytherapy. Mössbauer characterization showed that the iron oxides contained 64% magnetite, 18% hematite, 12% maghemite, and exhibit superparamagnetic behavior at room temperature. Transmission electron microscopy determined that the iron oxide particles were smaller than 15 nm, while magnetization was measured at 5 emu/g. Fourier transform infrared indicated the material was formed of Si-O-Si and Fe-O-Si bonds, while X-ray diffraction showed bands of amorphous silica from 5° to 23° and bands of iron oxide phases. X-ray fluorescence indicated 5.17% of incorporated samarium. The nanocomposite suspensions were subjected to an alternating magnetic field and the resulting heat dissipation was measured, falling within the ideal range for hyperthermia applications. Theoretical dosimetric calculation determined significant radioactive activity of 1.68x10-8 MBq.mg-1.Φ -1 after 24h decay time for 153Sm. The characteristics and behavior of these nanocomposites indicate that they may offer promise in applications involving hyperthermia for cancer treatment and a more accessible source for brachytherapy materials. naturalorigin natural origin magnetite maghemite FeO Fe O Fe3O γFe2O3, γFe2O3 γFeO γ Fe2O3, Fe2O3 γ-Fe2O3 respectively solgel sol gel coreshell core shell 64 18 hematite 12 temperature 1 nm emug emu g emu/g SiOSi Si FeOSi bonds Xray X ray 23 phases 517 17 5.17 1.68x108 168x108 x 1.68x10 8 68x10 1.68x10- MBq.mg1.Φ MBqmg1Φ MBqmgΦ MBq.mg 1.Φ MBq mg Φ - h 153Sm Sm materials γFe γFe2O Fe2O γ-Fe2O 6 2 51 5.1 68x108 168x10 1.68x1 68x1 mg1 MBqmg 1Φ 5. 168x1 1.68x 68x 168x

ABSTRACT Termites can create structures that alter the physical and chemical properties of soils. In this process, termites are selective about the soil constituents they will use to construct their mounds. Considering the common occurrence of termite mounds in Brazilian soils, this study aimed to investigate the selective action of termites in the mound building process. Samples were collected from six termite mounds and control soils (at a distance of 15 to 30 m from the termite mound) in different regions in Brazil to analyze the fine earth fraction. The content of clay fraction, organic C and Fe in pedogenic iron oxides increased in the mounds resulting in specific surface area increments. X-ray diffraction indicated a selectivity of termites by clay-sized particles such as kaolinite, gibbsite and iron oxides (hematite and goethite) rather than larger particles such as quartz. The proportion of low-crystalline iron oxides and the maghemite amount decreased in the mounds. The change of color parameters in the termite mounds was due to a combination of increase in clay fraction, organic carbon and iron oxides. The techniques used were sensitive, indicating changes and similarities between the control soils and the termite mounds. process at 1 3 fraction increments Xray X ray claysized sized kaolinite hematite goethite quartz lowcrystalline low crystalline sensitive

In this study, we evaluated the catalytic properties of hydroxyapatite (HA) nanoparticles (NPs) doped with Fe3O4/γ-Fe2O3 for the degradation of methylene blue (MB) dye using a photo-Fenton process at pH 2.5, 7.0, and 9.0. The HA NPs were characterized using X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectrometry, Raman spectroscopy, thermogravimetric analysis, fluorescence spectrometry, and point of zero charge experiments. Upon using unmodified HA NPs, 1.33 mL of H2O2 30% (v/v), and ultraviolet radiation (125 W Hg lamp), the discoloration values achieved at pH 2.5, 7.0, and 9.0 were 88.4, 44.8, and 58.1%, respectively. For the HA NPs modified with Fe3O4/γ-Fe2O3, the composition Ca2.5FeII2.5FeIII5(PO4)6(OH)2 yielded the best results during the photo-Fenton-based process, and discolorations of 100, 100, and 95.2% were achieved at pH 2.5, 7.0, and 9.0, respectively. To confirm the effectiveness of the Ca2.5FeII2.5FeIII5(PO4)6(OH)2 NPs, the total organic carbon (TOC) and toxicity effects on Lactuca sativa L. were evaluated, and reproducibility tests were performed. The TOC removal of the Ca2.5FeII2.5FeIII5(PO4)6(OH)2 NPs was ca. 90% and the toxicity of the MB dye was eliminated after 120 min of reaction; moreover, the NPs retained their physical stability and activity and were reused for 11 consecutive degradation experiments.

Abstract This work reports the preparation of magnetic polymeric microspheres based on poly(methyl methacrylate) and the investigation of these materials as catalysts in heterogeneous Fenton processes for the decolorization of methyl orange (MO). The microspheres were prepared by polymerization of the magnetic material together with the monomers by aqueous suspension polymerization. The microspheres had specific surface area of 48.2 m2 g-1. Mossbauer data indicated that the magnetic material was a mixture of magnetite (31%), maghemite (21%), and goethite (48%). Fenton reactions were performed by varying the concentration of H2O2, pH, composite mass, and contact time. The highest color removal rates (around 80%) were reached at pH 3.0, 20% w/v of composite, 20 minutes contact time, and 10 ppm of H2O2. The composite could be reused during four cycles with removal efficiency above 50%. The results indicated that the adsorption and oxidation mechanisms act together determining the variation of the MO dye removal.

Abstract The surface of Fe3O4 nanoparticles is very reactive and can oxidize to γ-Fe2O3 (maghemite) and α-Fe2O3 (hematite) structures. Based on this, the oxidation process of Fe3O4 nanoparticles must be prevented, and one of the strategies is surface functionalization with organic or inorganic molecules. Thus, this study analyzed the thermal behavior of Fe3O4 and Fe3O4-EDTA nanoparticles using X-ray diffraction (XRD), simultaneous thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC). Results showed that γ- Fe2O3 was obtained as an intermediate in Fe3O4 and Fe3O4-EDTA decomposition, as confirmed by TG-DTA and DSC curves. Moreover, Fe3O4-EDTA exhibited a temperature peak (Tp = 573.5°C) of phase transformation (γ-Fe2O3 → α-Fe2O3) higher than that of Fe3O4 (Tp = 533.0°C), confirming that EDTA molecules stabilized the nanoparticles efficiently. The kinetic behavior of samples changed, and the activation energy for functionalized samples decreased.

Abstract Environmental magnetism techniques enable us to reconstruct paleoclimate conditions in some deposition such as losses. The magnetic properties of minerals are used as proxies for environmental changes. For this study, loess/paleosol sequence of Kolet section at Neka, north-east of Iran were magnetically investigated. We applied environmental magnetism methods, to reconstruct paleoclimate changes. We investigated relationship between paleoclimate changes and environmental magnetism proxies like magnetic susceptibility (χ) variation. The laboratory techniques indicated the presence of main factor of magnetic property in loess/paleosol sequence, such as magnetite, maghemite and etc. We also estimated magnetically parameters (like SIRM, HIRM and etc.) to confirm concentrations of both aeolian and pedogenic particles versus variations of magnetic susceptibility enhancement. The χ values show prominent peaks for the three well developed soil and paleosol horizons, Recent Soil (S0), Upper Paleosol (S1) and Lower Paleosol (S2); which refer to warmer and wetter conditions. As result, we concluded that the increase/decreasing of magnetic susceptibility is coinciding with palaeosol/loess sequence, and probably with humid/arid conditions. Moreover, variations of magnetic susceptibility versus lithological column of Kolet section enabled us to recognize paleoclimatically periods known as interglacial/glacial cycles. We plotted variation of magnetic susceptibility (MS), Natural Remnant Magnetization (NRM), Frequency Dependent Susceptibility (χfd) and χfd% versus lithological plot of the loess profile to confirm loess/paleosol deposits of Kolet section bear magnetic particles. Then, we applied the obtained magnetic data as variation of magnetic susceptibility (MS) to indicate that there have been glacial/interglacial periods during over the past 50 ka. Hence, during this period of time, there are three major glacial occurrences in the study area. Also, we conclude there was no main glaciation occurrence since last 20.5 ka.

Resumen Las técnicas de magnetismo ambiental nos permiten reconstruir las condiciones del paleoclima para obtener resultados como las pérdidas. Las propiedades magnéticas de los minerales se utilizan como sustitutos de los cambios ambientales. En este estudio se investigó la secuencia magnética de loess-paleosol de la sección de Kolet en Neka, al noreste de Irán. Fueron aplicados métodos de magnetismo ambiental para reconstruir los cambios del paleoclima. Se investigó la relación entre los cambios del paleoclima y los proxies del magnetismo ambiental como la variación de la susceptibilidad magnética (χ). Las técnicas de laboratorio indicaron la presencia del factor principal de propiedad magnética en la secuencia de loess-paleosol, como magnetita, maghemita, etc. También, se estimó magnéticamente parámetros (como SIRM, HIRM, etc.) para confirmar concentraciones de partículas tanto eólicas como pedogénicas frente a variaciones de la mejora de la susceptibilidad magnética. Los valores de χ muestran picos prominentes para los tres horizontes de suelos y paleosuelos bien desarrollados, Suelo reciente (S0 por sus siglas en inglés), Paleosol superior (S1, por sus siglas en inglés) y Paleosol inferior (S2, por sus siglas en inglés); que se refieren a condiciones más cálidas y húmedas. Como resultado se obtuvo que el aumento/disminución de la susceptibilidad magnética coincide con la secuencia paleosol-loess, y probablemente con condiciones húmedas/áridas. Además, las variaciones de la susceptibilidad magnética versus la columna litológica de la sección de Kolet permitieron reconocer períodos paleoclimáticos conocidos como ciclos interglaciares/glaciales. Se trazó la variación de la susceptibilidad magnética (MS, por sus siglás en inglés), la magnetización del remanente natural (NRM, por sus siglás en inglés), la susceptibilidad dependiente de la frecuencia (χfd) y de χfd% versus la gráfica litológica del perfil de loess para confirmar que los depósitos de loess/paleosol de la sección de Kolet tienen partículas magnéticas. Luego, aplicamos los datos magnéticos obtenidos como variación de susceptibilidad magnética (MS, por sus siglás en inglés) para indicar que ha habido períodos glaciales/interglaciares durante los últimos 50 ka. Por lo tanto, durante este período de tiempo, hay tres ocurrencias glaciares importantes en el área de estudio. Además, concluimos que no hubo ocurrencia de glaciaciones principales desde los últimos 20.5 ka.

Resumen En la última década los nanomateriales magnéticos se han utilizado ampliamente en el campo de la química, la física, la ingeniería y la medicina debido a sus propiedades ópticas, magnéticas y de conducción, y como agentes de contraste en resonancia magnética. Se ha evaluado su influencia en el tratamiento de tumores cancerosos y está despertando gran interés en sistemas de reparación ambiental como absorbentes magnéticos que atrapan partículas de metal y algunos contaminantes. En este estudio se analizó la influencia de los parámetros de proceso en la obtención de nanopartículas magnéticas bajo tres métodos de síntesis química. La caracterización morfológica se hizo por microscopía electrónica de barrido (SEM), su composición elemental se estudió mediante espectroscopia de energía dispersiva de rayos x (EDS), y su estructura, mediante difracción de rayos x (XRD). Los resultados evidenciaron una gran influencia del método de obtención, como se reflejó en la variabilidad del tamaño de las nanopartículas. Es de resaltar la obtención de partículas a escala nanométrica, con predominancia de estructuras Fe3O4 (magnetita) y Fe2O3 (maghemita), lo cual supondría propiedades de superparamagnetismo que abrirían el camino a un amplio abanico de aplicaciones futuras con su producción a bajo costo y de fácil acceso.

Abstract In the last decade, magnetic nanomaterials have been widely used in the fields of chemistry, physics, engineering, and medicine due to their optical, magnetic, and conductive properties, and as contrast agents in magnetic resonance. Their influence in the treatment of cancerous tumors has been evaluated and has sparked great interest in its use in environmental repair systems such as magnetic absorbers that trap metal particles and some contaminants. Here we analyze the influence of process parameters to obtain magnetic nanoparticles under three chemical synthesis methods. Its morphological characterization was performed by scanning electron microscopy (SEM), its elemental composition by energy dispersive spectroscopy (EDS), and its structure by x-ray diffraction (XRD). Our results showed that the obtention method had a great influence as evidenced by the variability in nanoparticle sizes. It is worth highlighting that we obtained particles at a nanometric scale, especially Fe3O4 (magnetite) and Fe2O3 (maghemite) structures, with potential superparamagnetism properties that could open a wide range of future applications for the production of these materials at low cost and easy access.

In this work, bio-oil (an organic matrix rich in oxygen functionalities) was used to efficiently dissolve and disperse Fe3+ which upon thermal treatment produced a carbon containing dispersed and encapsulated Fe oxide magnetic nanoparticles. These materials were prepared by dissolution of 8, 16 and 24 wt.% Fe3+ salt in bio-oil followed by treatment at 400, 450, 500 or 600 ºC in N2 atmosphere. X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopies (TEM), elemental analysis, thermogravimetric-mass spectrometry (TG-MS), potentiometric titration, Raman and Mössbauer spectroscopies showed that Fe3+ species in bio-oil is reduced to produce magnetic nanoparticles phases: magnetite Fe3O4 and maghemite γ-Fe2O3. At low temperatures, the iron phases were less protected, and the carbon matrix was more reactive, while in temperatures above 500 ºC, the iron phases were more stable, however, the carbon matrix was less reactive. Reaction of these magnetic carbon materials with concentrated H2SO4 produced surface sulfonic acidic sites (ca. 1 mmol g-1), especially for the materials obtained at 400 and 450 ºC. The materials were used as catalysts on esterification reaction of oleic acid with methanol at 100 ºC and conversions of 90% were reached, however, after 2 consecutive uses, the conversion decreased to 30%, being required more studies to improve the material stability.

Abstract: This article presents the results obtained from a compositional study of paint found on ceramic pieces of the Goya-Malabrigo style through the combined application of Raman spectroscopy (rs), X-ray diffraction (xrd), and scanning electronic microscopy/ energy-dispersive x-ray microanalysis (sem-edx). The samples are from pre-Hispanic sites in the Paraná River basin, in Entre Ríos province, northeast Argentina. The analyses detected hematite and maghemite in the red paintings and hydroxyapatite as the main pigment in the white paintings.

Resumen: En este artículo se presentan los resultados obtenidos a partir de la aplicación combinada de espectroscopia Raman (rs), difracción de rayos-X (xrd), microscopía electrónica de barrido y microanálisis por dispersión de energía de rayos-X (sem- edx) para el estudio composicional de pinturas en alfarerías de estilo Goya-Malabrigo. Las muestras proceden de sitios prehispánicos de la cuenca del río Paraná, localizados en la provincia de Entre Ríos, al nordeste de Argentina. En las pin turas rojas se detecta la utilización de hematita y maghemita mientras que, en las pinturas blancas, se evidencia el empleo de hidroxiapatita como pigmento principal.

Abstract Activated biochars were prepared from residues of medium density fiberboard (MDF) produced by the furniture industry. Biomass residue was pre-treated with FeCl3 in two different FeCl3:biomass ratios (0.5:1 and 1:1, w/w) aiming to produce a matrix embedded with iron oxide. The pyrolysis process produced maghemite on the biochar surface and its magnetic properties were confirmed by its attraction to a hand magnet and its magnetic susceptibility. Samples were also characterized using scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), surface area by BET-N2, Fourier transform infrared (FTIR), X-ray diffraction, magnetic susceptibility, and cation exchange capacity (CEC). Magnetic biochar exhibited up to twelve-fold higher surface area than the non-magnetic biochar, which varies according the maghemite particles content. Iron oxide on biochar surface also contributed for increasing CEC around ten-fold compared to non-magnetic biochars. Phosphorus adsorption isotherms showed that these magnetic biochars have high capacity to sorb oxyanions like phosphate, especially at lower pH. Thus, these magnetic biochars could be used to clean water bodies contaminated with oxyanions in acidic conditions.

ABSTRACT Nanomaterial-based biocatalysts have emerged as current carriers suitable for enzyme immobilization. The nano-sized materials provide large surface area for enzyme attachment, thus increasing the probability for its efficient catalyst activity. By using magnetized nanomaterials, enhancement of the downstream processing is evident as it eases the immobilized enzyme separation from the reaction mixture further. Lipase / maghemite composites were prepared by initial maghemite surface modification to cater to the needs for biocatalyst attachment. Surface modification using chitosan and subsequent cross-linking with glutaraldehyde provide a suitable environment for the enzyme to be immobilized. Optimization of the conditions for lipase immobilization was carried out using a response surface methodology (RSM) experimental design to obtain the precise optimized conditions for the process. Selected process variables involved were chosen and optimized conditions for lipase immobilization were 9 hour incubation time, 55°C incubation temperature and 12 % (v/v) glutaraldehyde content. The optimized immobilized lipase activity was 1.8 U. Characterizations of the on synthesized materials were also performed. The size distribution of maghemite nanomaterials was mainly within the range of 2-3 nm. Thermal properties of the synthesized maghemite was investigated using DSC and TGA analyses and we found that maghemite changes to hematite at 456.3°C. Magnetic properties of both untreated and lipase immobilized maghemite were studied using VSM and both were superparamagnetic nanomaterials with saturation magnetizations of 34.3 and 80.3, respectively.