scholarly journals Magnetic Behavior of Carbon Materials Made from Biomass by Fe-Assisted Hydrothermal Carbonization

Molecules ◽  
2019 ◽  
Vol 24 (21) ◽  
pp. 3996 ◽  
Author(s):  
Mara Olivares ◽  
Silvia Román ◽  
Beatriz Ledesma ◽  
Alfredo Álvarez

Biomass magnetic materials were synthesized by several hydrothermal carbonization methods, by which iron was provided in different ways: as FeCl3 prior to or during hydrothermal carbonization, as pure Fe particles, or as magnetic ferrofluid, followed or not by pyrolysis processes. The materials were thoughtfully characterized in terms of elemental composition, thermal degradation, porosity (N2 adsorption, SEM micrography), surface chemistry (FTIR spectroscopy, XRD diffraction), and magnetization curves on a self-made installation. The results indicated that the process design can significantly improve the structure and chemistry of the material, as well as the magnetization effect induced on the adsorbent. Fe as FeCl3 was more interesting in regards to the development of porosity, mainly creating micropores, although it did not provide magnetism to the material unless a further pyrolysis was applied. Thermal treatment at 600 °C did not only increase the BET-specific surface (SBET) (262 m2 g−1) of the hydrochar, but also involved the transformation of Fe into magnetite, providing magnetic behavior of the hydrochar. Increasing pyrolyisis temperature to 800 °C even enhanced a better development of porosity (SBET of 424 m2 g−1) and also increased the specific magnetic susceptibility of the hydrochar as a result of the further transition of Fe into wustite and hydroxi-ferrite.

2021 ◽  
Vol 7 (7) ◽  
pp. 99
Author(s):  
Linh Trinh ◽  
Eric Rivière ◽  
Sandra Mazerat ◽  
Laure Catala ◽  
Talal Mallah

The collective magnetic behavior of photoswitchable 11 nm cyanide-bridged nanoparticles based of the Prussian blue analogue CsCoFe were investigated when embedded in two different matrices with different concentrations. The effect of the intensity of light irradiation was studied in the less concentrated sample. Magnetization studies and alternating magnetic susceptibility data are consistent with a collective magnetic behavior due to interparticle dipolar magnetic interaction for the two compounds, even though the objects have a size that place them in the superparamagnetic regime.


2003 ◽  
Vol 17 (24) ◽  
pp. 1271-1275 ◽  
Author(s):  
I. ARDELEAN ◽  
C. ANDRONACHE ◽  
P. PǍŞCUŢǍ

The temperature dependence of the magnetic susceptibility of x Fe 2 O 3·(100-x)-[ P 2 O 5· CaO ] glasses with 0<x≤50 mol % have been investigated. These data revealed that the valence states and the distribution of iron ions in the glass matrix depend on the Fe 2 O 3 content. For the glasses with x≤1 mol % only Fe 3+ ions are evidenced. In the case of the glasses with 3≤x≤35 mol % both Fe 3+ and Fe 2 ions co-exist in the P 2 O 5· CaO glass matrix, the Fe 2+ ion content is higher than that of the Fe 3+ ions for glasses with x≥10 mol %. For the glasses with x>35 mol %, the evaluated values of the μ eff indicate either the presence of Fe + ions or the coordination influence on the magnetic moment of iron ions, but the presence of small quantities of the antiferromagnetic or ferrimagnetic interactions between iron ions in studied temperature range cannot be excluded. The high temperature susceptibility results indicate that the iron ions are isolated or participate in dipole-dipole interactions for glasses with x≤35 mol % and are antiferromagnetically coupled for higher contents of Fe 2 O 3.


2014 ◽  
Vol 43 (19) ◽  
pp. 7263-7268 ◽  
Author(s):  
Tiffany M. Smith ◽  
Michael Tichenor ◽  
Yuan-Zhu Zhang ◽  
Kim R. Dunbar ◽  
Jon Zubieta

The three-dimensional [Co3(OH)2(H2O)2(aptet)4] exhibits magnetic properties consistent with a ferrimagnetic chain with the non-compensating resultant moment of one Co(ii) per trinuclear Co(ii) subunit and ac magnetic susceptibility indicative of glassy-like magnetic behavior.


2019 ◽  
Vol 41 (1) ◽  
pp. 72-72
Author(s):  
Jilei Liang Jilei Liang ◽  
Mengmeng Wu Mengmeng Wu ◽  
Hongmei Cai Hongmei Cai ◽  
Hao Wang Hao Wang ◽  
Hua Huang Hua Huang ◽  
...  

Carbon microspheres (CMs) with a diameter of 5-10 μm have been synthesized by hydrothermal carbonization of starch and L-arginine. The surface property and structure of CMs were examined by FT-IR spectra, N2 adsorption-desorption isotherms and SEM images. These characterizations indicated that the L-arginine does not connect into the CMs but it promotes the starch hydrolysis and polymerization-condensation reaction of intermediate, which accelerates the formation of CMs and improves the yield in shorter time. The surface property of CMs determines adsorption capacity for acetic acid. By contrast, the porosity resulted from the carbonization at 500 and#176;C dominates the adsorption capacity for acetic acid.


2020 ◽  
Vol 235 (1-2) ◽  
pp. 7-13
Author(s):  
Jutta Kösters ◽  
Christian Paulsen ◽  
Frank Stegemann ◽  
Birgit Heying ◽  
Valérie Galéa-Clolus ◽  
...  

AbstractSystematically twinned olivenite (Cu2(AsO4)OH) single crystals from Cap Garonne, Mine du Pradet, France, were studied by X-ray diffraction: P 21/n, a = 822.69(6) pm, b = 861.88(9) pm, c = 594.06(9) pm, β = 90.000(6)°, wR = 0.0224, 1621 F2 values, 79 variables and a domain ratio of 0.501(1)/0.499(1). The temperature dependence of the magnetic susceptibility was well reproduced with a square-spin cluster model and an antiferromagnetic spin-exchange parameter of J/kB = 157(3) K.


2010 ◽  
Vol 968 (1-3) ◽  
pp. 67-75
Author(s):  
Fang Xuan ◽  
Zheng-Fang Tian ◽  
Xiao-Ming Ren ◽  
Hai-Bao Duan ◽  
Qing-Jin Meng

2021 ◽  
Vol 1028 ◽  
pp. 15-20
Author(s):  
Muhammad Abdan Syakuur ◽  
Yati Maryati ◽  
Togar Saragi ◽  
Risdiana

Structure and magnetic properties of electron-doped superconducting cuprates have been investigated in order to study the effect of magnetic impurity to its physical properties. Here, we reported structure and magnetic properties of Eu1.88Ce0.12Cu1-yZnyO4+α-δ (ECCZO) with y = 0 and 0.03. The properties of ECCZO have been studied from X-ray diffraction data and temperature dependence of magnetic susceptibility data, to elucidate the effect of partial substitution of non-magnetic impurity Zn for Cu to its structure, Tc and the value of magnetic moments per unit volume extracted from susceptibility data in normal state. Magnetic-susceptibility measurements were carried out down to 2 K on-field cooling at 5 Oe for Eu1.88Ce0.12Cu1-yZnyO4+a-d with y = 0 and 0.03. For ECCZO sample with y = 0 and d = 0.0669 indicated the change of magnetic behavior from paramagnetic to diamagnetic below 12 K which is addressed to the Tc onset of this samples. Diamagnetic behavior is observed starting from about 12 K. Above 12 K, all samples show paramagnetic behavior with the values of the magnetic moment in every volume unit increased with increasing Zn.


Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 655 ◽  
Author(s):  
Francesco Veltri ◽  
Francesca Alessandro ◽  
Andrea Scarcello ◽  
Amerigo Beneduci ◽  
Melvin Arias Polanco ◽  
...  

Porous carbon materials are currently subjected to strong research efforts mainly due to their excellent performances in energy storage devices. A sustainable process to obtain them is hydrothermal carbonization (HTC), in which the decomposition of biomass precursors generates solid products called hydrochars, together with liquid and gaseous products. Hydrochars have a high C content and are rich with oxygen-containing functional groups, which is important for subsequent activation. Orange pomace and orange peels are considered wastes and then have been investigated as possible feedstocks for hydrochars production. On the contrary, orange juice was treated by HTC only to obtain carbon quantum dots. In the present study, pure orange juice was hydrothermally carbonized and the resulting hydrochar was filtered and washed, and graphitized/activated by KOH in nitrogen atmosphere at 800 °C. The resulting material was studied by transmission and scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and nitrogen sorption isotherms. We found porous microspheres with some degree of graphitization and high nitrogen content, a specific surface of 1725 m2/g, and a pore size distribution that make them good candidates for supercapacitor electrodes.


2015 ◽  
Vol 3 (4) ◽  
pp. SAB33-SAB42 ◽  
Author(s):  
Eleni Kokinou

The magnetic behavior of the geologic formations around the Giouchtas or Juchtas Mountain (Mt.) in Central Crete, Greece, has been studied. The magnetic parameters (magnetic susceptibility [MS] and temperature dependence of the magnetic susceptibility) of 160 surface soil samples were interpreted based on available information (e.g., topographic, geologic, and historical) for the area of study. The soil samples have been collected from the low- and high-elevation regions of Giouchtas Mt. The low-elevation region, surrounding a north–south asymmetric ridge (strongly affected by the tectonic activity), is mainly covered by Miocene and recent sediments, whereas the high-elevation region is dominated by limestones. Differences in the spatial distribution of the MS and the thermomagnetic behavior of the soil samples indicated the strong influence of natural and anthropogenic factors on the geologic formations.


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