Specific Saturation Magnetization Research Articles

Formation of Fe3O4/C composite during pyrolysis of FeCl3-loaded pineapple (Ananas comosus) leaves

Pineapple leaves are an abundant and underutilized biomass resource released from cutting old plants with low productivity. The renewable waste was, therefore, used for the preparation of the Fe3O4/C composite via single-stage pyrolysis with FeCl3 addition. The results revealed that FeCl3-activation produced Fe3O4 crystals with an estimated content of 44 wt% in the resulting Fe3O4/C composite. In addition, the specific saturation magnetization of Fe3O4/C reached 4.62 emu/g, which supported its magnetic separatability. The material was accordingly explored as an oxidation catalyst for treating methyl orange (50 ppm) at pH 3.0. As a result, Fe3O4/C partly removed methyl orange with an adsorption capacity of 9.9±2.4 mg/g. When H2O2 (300 ppm) was added, 0.40 g/L of Fe3O4/C decolorized 93±2% methyl orange with an average rate of 72±3 mg.g−1.h−1. Furthermore, this decolorization obeyed pseudo-first-order kinetics with a rate constant of 0.030 min−1. Overall, the findings from this study strongly advocate for the use of low-cost Fe3O4/C as a highly effective catalyst for methyl orange removal from wastewater. Moreover, these results pave the way for further exploration of pineapple leaf-derived Fe3O4/C for a wide range of potential applications, contributing to sustainable waste management and green chemistry practices.

Gallium substitution influence on microstructure and magnetic properties of Y-type Ba0.5Sr1.5Zn2Fe12O22 hexaferrites

Y-type hexagonal ferrites of Ba0.5Sr1.5Zn2Fe(12-x)GaxO22 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) are synthesized by chemical co-precipitation method. X-ray diffraction (XRD) analysis reveals that the samples are single-phase and the space group is R3¯m. The field-emission scanning electronic microscope (FE-SEM) results indicate that the grains are regular fibrous shape with a width of about 2–5 µm and a thickness of 1–3 µm. In the M-T diagram, it can be observed that the temperature at which the transition from helical to ferrimagnetic (TS) increases first and then decreases with increasing substitution amount x. From σ-H, the values of coercive field (HC) experience alternating decreases and increases, and reaches a maximum value of 567.34 Oe at x = 0.8. While the specific saturation magnetization (σS) values exhibit a monotonic decrease with the increasing x. The variations in magnetic properties can tentatively be ascribed to the effect of Ga3+ substitution. These results above might be used as promising candidates in electric devices.

Gyromagnetic properties of Cu-substituted NiZn ferrites for millimeter-wave applications

In this work, NiCuZn ferrites with different CuO contents were prepared by solid-state method. The influences of the divalent Cu2+ on the crystal structure, microstructure and magnetic properties of NiCuZn ferrite were studied in detail. X-ray diffraction characterization showed that Cu2+ may either replace Ni2+ and enter into crystal lattice, or distributed at grain boundaries in the form of compound. SEM results showed that adding appropriate amount of CuO can promote grain growth and prepare dense NiCuZn ferrites. Especially, the density of the ferrite sample reaches its maximum value of 5.23 g/cm3 when the amount of CuO is 0.20. However, superfluous Cu2+ exists in the form of liquid phase at local grain boundaries once the content of Cu2+ reached 0.25. Moreover, the magnetic hysteresis loops revealed that the specific saturation magnetization first increased and then decreased and the highest value of 76.6 emu/g was obtained at x = 0.10. Consequently, a NiCuZn ferrite with an appropriate microstructure and with high density (5.16 g/cm3), high saturation magnetization (76.0 emu/g), low ferromagnetic resonance (FMR) linewidth (160 Oe) and 4πMs (4930 G) could be obtained at a Cu content of x = 0.15.

Efficient removal of amoxycillin antibiotics onto magnetic graphene oxide: adsorption performance, mechanism, and regeneration exploration

ABSTRACT The present study was done to synthesise an adsorbent, i.e. magnetic graphene oxide (MGO) nanocomposite, which was performed based on a facile precipitation method and was utilised in experiments for removing amoxycillin (AMX). The characteristics of the prepared adsorbent were defined based on commonly utilised analyses (SEM, XRD, BET, TEM, FTIR, VSM, and pHpzc). According to kinetic studies, the PSO model was found as an applicable model for describing data. Moreover, the two-step diffusion process, i.e. diffusion in the boundary layer and the porous structures, was perceived for the evaluated process based on the IPD model. The isotherm models, including Langmuir, Freundlich, Temkin, and D–R, were employed for fitting data and calculating AMX adsorption capacity, among which Langmuir was the best one; using this model, the maximum adsorption capacities for MGO were 91.4, 103.9, 112.3, and 122.5 mg/g, which were achieved at 20, 30, 40, and 50°C. In addition, a feasible, spontaneous, and endothermic process was found for the adsorption of AMX ions, according to thermodynamic studies. The highest percentage of removal (100%) was obtained for the initial concentration of 25 mg/L at 50°C using the adsorbent dose of 1.5 g/L at a pH of 5 and a contact time of 90 min. The values of 74.4 m2/g and 27.74 emu/g were detected for the specific surface area and saturation magnetisation values of the MGO, respectively. The overall results were representative of the suitability of the MGO as an adsorbent for removing AMX from aqueous media.

Feasibility Analysis of Brain Perfusion Using Polyaspartic Acid Surface-Modified Superparamagnetic Contrast Agent

This research was aimed to construct polyaspartic acid (PASP) surface-modified magnetic resonance imaging (MRI) contrast agent nanoparticles (NPs) and preliminarily demonstrate the feasibility of using the NPs for MRI cerebral perfusion. Ultrasmall superparamagnetic iron oxide (USPIO) NPs were fabricated by a one-step chemical coprecipitation methodology, and surface modification of USPIO NPs was performed using PASP as the surface modifier to prepare PASP-USPIO NPs. The physicochemical properties of the NPs were detected, and their specific structural ability with HUVECs was visualized by Prussian blue staining. With the contrast agent gadolinium-diethylene triamine pentaacetate (Gd-DTPA) as the control group, the intravenous bolus of USPIO and PASP-USPIO was analyzed and a brain MRI scan of New Zealand white rabbits was performed. The relative cerebral blood volume (rCBV) and maximum signal reduction ratio (SRRmax) values of cerebral gray matter and white matter were calculated based on the plotted time-signal intensity. The results showed that the USPIO and PASP-USPIO NPs were successfully prepared. The average particle sizes were 40.1±5.5 nm and 42.7±6.9 nm, respectively, and the specific saturation magnetization was 86.9 A m2 ·kg−1 and 51.3 A m2 ·kg−1, respectively. Relative to USPIO, human umbilical vein endothelial cells (HUVECs) stained with Prussian blue positively in vitro in the PASP-USPIO group were notably increased, while the rate of change in the signal-to-noise ratio of imaging in vivo was substantially decreased. The time-signal intensity curves were plotted, and it was found that the rCBV of gray matter, rCBV of white matter, SRRmax of gray matter, and SRRmax of white matter in the USPIO group and PASP-USPIO group were greatly increased relative to control group (P < 0.05), while the SRRmax ratio of gray matter to white matter was decreased (P < 0.05). Additionally, the rCBV in the gray matter and rCBV in the white matter of the PASP-USPIO group were drastically increased in contrast to the USPIO group (P < 0.05). In short, the constructed PASP surface-modified USPIO NPs can become a novel MRI contrast agent for monitoring hemodynamic changes in brain tissue.

Effect of Cr3+ Doping on Magnetic Properties of Zn-Mg Ferrite Nanoparticles

Zn0.6Mg0.4CrxFe2−xO4 (0 ≤ x ≤ 0.4) nanoparticles were synthesized using a hydrothermal technique. The obtained magnetic nanoparticles (MNPs) exhibited a spinel structure, where the lattice constant decreased with the Cr3+ ion content. The doping of Cr3+ ion (x = 0.1) increased the specific saturation magnetization to 46.4 emu/g but decreased to 20.0 emu/g with the further increase in the Cr3+ ion content to x = 0.4. The decrement in Curie temperature was ascribed to the weakened super-exchange interaction between the metal ions located at A-sites and B-sites, which arose from the doping of the Cr3+ ion. The T2-weighted images gradually darkened with the increase in Zn0.6Mg0.4Cr0.1Fe1.9O4 nanoparticles concentration, suggesting that the nanoparticles can enhance the image contrast. Zn0.6Mg0.4CrxFe2−xO4 (0 ≤ x ≤ 0.4) nanoparticles were able to heat the agar phantom to the hyperthermia temperature under the safe alternating magnetic field, which showed their potential in the magnetic induction hyperthermia.

Microstructure and magnetization study of Li and Li–Zn ferrites synthesized by an electron beam

Lithium ferrites are widely used in high frequency electronic devices. The present work reports structural and magnetization analysis of lithium (Li0.5Fe2.5O4) and lithium-zinc (Li0.4Fe2.4Zn0.2O4) ferrites synthesized by electron beam heating (RT) of powdered and compacted samples. The synthesis was carried out at 600 and 750 °C for up to 120 min using 2.4 MeV electron beam generated by an ILU-6 pulsed electron accelerator. The characteristics of the samples synthesized by RT were compared with the ones of samples obtained by traditional thermal heating under the same temperature and time conditions. From XRD and thermomagnetometric analyses, α-Li0.5Fe2.5O4 ordered spinel phase and Li0.5(1−x)Fe2.5−0.5xZnxO4 ferrite phase with different zinc substitution were formed from Fe2O3/Li2CO3 and Fe2O3/Li2CO3/ZnO reagents, respectively. RT synthesis significantly increases the rate of interaction between the initial powders and, as a consequence, the rate of ferrite phase formation. In this case, lithium-containing ferrites can be successfully achieved from compacted powders at 750 °C, which is lower than the temperature of synthesis in conventional thermal heating. The average crystallite sizes calculated from the XRD and BET analyses were 114 nm for Li, 120 nm for Li–Zn ferrites and 142 for Li, 150 nm for Li–Zn, respectively. The specific saturation magnetization and Curie temperature were estimated and are 60 emu/g for Li, 70 emu/g for Li–Zn ferrites and 632 °C for Li, 492 °C for Li–Zn ferrites, respectively. The data obtained in this work are of considerable interest for the creation of a technology for producing ferrites at low synthesis temperatures.

Ex-situ magnetic activated carbon for the adsorption of three pharmaceuticals with distinct physicochemical properties from real wastewater.

Pharmaceuticals are able to evade conventional wastewater treatments and therefore, are recurrently found in the environment with proven potential to cause harm to human and wildlife. Adsorption onto activated carbon (AC) is a promising complement. However, AC production from non-renewable resources and its difficult after-use recuperation are prohibitive. Hence, a waste-based magnetic activated carbon (MAC) was produced from paper mill sludge, via an ex-situ synthesis, for the adsorptive removal of carbamazepine (CBZ), sulfamethoxazole (SMX) and ibuprofen (IBU) from ultrapure water and wastewater. The MAC was obtained through the promotion of electrostatic interactions between magnetic and activated carbon particles in a water suspension at controlled pH between the points of zero charge of both surfaces. The optimized condition (MACX3) presented remarkable properties regarding specific surface area (SBET=795m2 g-1) and saturation magnetization (MS=19emug-1). Kinetic and equilibrium adsorption studies were performed under batch conditions. Adsorption equilibrium was reached in up to 30min for all pharmaceuticals in both matrices, proving the low dependence on the adsorbate and the broad applicability of MACX3 in pharmaceutical adsorption. Regarding equilibrium experiments, high Langmuir maximum adsorption capacities (qm) were achieved in ultrapure water (up to 711 ± 40 µmol g-1). Equilibrium studies in wastewater revealed a decay in qm when compared to ultrapure water: 28% for CBZ (468 ± 20 µmol g-1 (111 ± 5 mg g-1)), 78% for SMX (145±10 µmol g-1 (37 ± 3 mg g-1)) and 62% for IBU (273 ± 8 µmol g-1 (56 ± 2 mg g-1)), attributed to the wastewater pH, which dictates the speciation of the pharmaceuticals and controls electrostatic interactions between pharmaceuticals and MAC, and to competition effects by organic matter. It was demonstrated the promising applicability of a waste-based ex-situ MAC, rapidly retrievable from water, as an alternative tertiary wastewater treatment for pharmaceuticals removal.

Technological Aspects of Lithium-Titanium Ferrite Synthesis by Electron-Beam Heating.

Solid-phase synthesis of lithium-titanium ferrite by electron-beam heating of a Fe2O3-Li2CO3-TiO2 initial reagents mixture with different history (powder, compact, mechanically activated mixture) was studied using X-ray diffraction, thermomagnetometric and specific saturation magnetization analyses. Ferrite was synthesized using an ILU-6 pulsed electron accelerator; it generated electrons with electron energy of 2.4 MeV to heat samples to temperatures of 600 and 750 °C. The isothermal holding time upon reaching the synthesis temperature was 0-120 min. The efficiency of ferrite synthesis by electron-beam heating was evaluated via comparison of the characteristics of the obtained samples with those synthesized by conventional ceramic technology under similar temperature-time conditions. It was found that the rate of ferrite formation depends on the heating method, temperature, synthesis time, density, and activity of the initial mixture. It was shown that sample compaction provides the preferential formation of unsubstituted lithium ferrite of Li0.5Fe2.5O4 composition with a Curie temperature of at ca. 630 °C in both synthesis methods. High-energy electron-beam heating of the mechanically activated mixture significantly accelerates synthesis of Li0.6Fe2.2Ti0.2O4 substituted ferrite, for which the Curie temperature and specific saturation magnetization were recorded as 534 °C and 50 emu/g, respectively. Therefore, LiTi ferrites can be obtained at a lower temperature (750 °C) and with a shorter synthesis time (120 min) compared to traditional ceramic technology.

The Formation, Properties and Use of Dispersed Iron-Graphite Metallurgical Waste

Dispersed wastes containing graphite, iron, and its oxides, getting into the air and accumulating in landfills, cause serious harm to human health and the environment. Moreover, even if the issue of the localization of these wastes has been solved successfully, their disposal has not yet been fully organized. In the present study, a systematic analysis of the dispersed iron-graphite waste (IGW) conditions for the formation at metallurgical enterprises, their structure, and their properties were carried out. In this case, special attention is focused on the electrophysical properties: specific saturation magnetization and volume resistivity. The presence of magnetic properties in IGW, combined with low electrical resistivity, makes IGW a promising and inexpensive raw material for obtaining cheap composite materials with radio shielding and radio absorbing properties in the microwave range. As a result of the research, effective ways of improving the magnetic properties of IGW by high-temperature treatment were obtained. The practical result of the research was the development and implementation of a technological scheme of dispersed IGW complex processing, which makes it possible to solve a twofold task – to exclude the ingress of iron-graphite wastes into the environment and to obtain a cheap material for protection against microwave radiation.

On As(III) Adsorption Characteristics of Innovative Magnetite Graphene Oxide Chitosan Microsphere.

A magnetite graphene oxide chitosan (MGOCS) composite microsphere was specifically prepared to efficiently adsorb As(III) from aqueous solutions. The characterization analysis of BET, XRD, VSM, TG, FTIR, XPS, and SEM-EDS was used to identify the characteristics and adsorption mechanism. Batch experiments were carried out to determine the effects of the operational parameters and to evaluate the adsorption kinetic and equilibrium isotherm. The results show that the MGOCS composite microsphere with a particle size of about 1.5 mm can be prepared by a straightforward method of dropping FeCl2, graphene oxide (GO), and chitosan (CS) mixtures into NaOH solutions and then drying the mixed solutions at 45 °C. The produced MGOCS had a strong thermal stability with a mass loss of <30% below 620 °C. The specific surface area and saturation magnetization of the produced MGOCS was 66.85 m2/g and 24.35 emu/g, respectively. The As(III) adsorption capacity (Qe) and removal efficiency (Re) was only 0.25 mg/g and 5.81% for GOCS, respectively. After 0.08 mol of Fe3O4 modification, more than 53% of As(III) was efficiently removed by the formed MGOCS from aqueous solutions over a wide pH range of 5–10, and this was almost unaffected by temperature. The coexisting ion of PO43− decreased Qe from 3.81 mg/g to 1.32 mg/g, but Mn2+ increased Qe from 3.50 mg/g to 4.19 mg/g. The As(III) adsorption fitted the best to the pseudo-second-order kinetic model, and the maximum Qe was 20.72 mg/g as fitted by the Sips model. After four times regeneration, the Re value of As(III) slightly decreased from 76.2% to 73.8%, and no secondary pollution of Fe happened. Chemisorption is the major mechanism for As(III) adsorption, and As(III) was adsorbed on the surface and interior of the MGOCS, while the adsorbed As(III) was partially oxidized to As(V) accompanied by the reduction of Fe(III) to Fe(II). The produced As(V) was further adsorbed through ligand exchange (by forming Fe–O–As complexes) and electrostatic attraction, enhancing the As(III) removal. As an easily prepared and environmental-friendly composite, MGOCS not only greatly adsorbs As(III) but also effectively removes Cr(VI) and As(V) (Re > 60%) and other metals, showing a great advantage in the treatment of heavy metal-contaminated water.

ZnO/ZnFe2O4/zeolite composite catalyst for peroxymonosulfate oxidation and photocatalysis

Magnetic ZnO/ZnFe2O4/Zeolite (ZFZ) catalysts were prepared by a solvothermal-microwave method and used for advanced oxidation processes. Careful investigations indicate ZFZ has a core-shell structure with ZnO/ZnFe2O4 nanoparticles covered on the surface of Na-A zeolite. The specific saturation magnetization of ZFZ is up to 15.276 emu/g, which is sufficient for efficient magnetic separation. Experiments on advanced oxidation degradation of Rhodamine B indicate that ZFZ have remarkable catalytic activity for peroxymonosulfate oxidation. The degradation rate increased more than 3 times under UV-light irradiation, suggesting that ZFZ has stronger photocatalysis. The highest decomposition rate could reach 98.55 %. And after 5 cycles, a 79.11 % degradation rate still remained.

Impact of Nd3+ Substitutions on the Structure and Magnetic Properties of Nanostructured SrFe12O19 Hexaferrite.

In this study, SrFe12-xNdxO19, where x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5, was prepared using high-energy ball milling. The prepared samples were characterized by X-ray diffraction (XRD). Using the XRD results, a comparative analysis of crystallite sizes of the prepared powders was carried out by different methods (models) such as the Scherrer, Williamson–Hall (W–H), Halder–Wagner (H–W), and size-strain plot (SSP) method. All the studied methods prove that the average nanocrystallite size of the prepared samples increases by increasing the Nd concentration. The H–W and SSP methods are more accurate than the Scherer or W–H methods, suggesting that these methods are more suitable for analyzing the XRD spectra obtained in this study. The specific saturation magnetization (σs), the effective anisotropy constant (Keff), the field of magnetocrystalline anisotropy (Ha), and the field of shape anisotropy (Hd) for SrFe12-xNdxO19 (0 ≤ x ≤ 0.5) powders were calculated. The coercivity (Hc) increases (about 9% at x = 0.4) with an increasing degree of substitution of Fe3+ by Nd3+, which is one of the main parameters for manufacturing permanent magnets.

Co-Precipitation Synthesis of Clay-Magnetite Nanocomposite for Adsorptive Removal of Synthetic Dye in Wastewater of Benang Bintik Batik

Clay is a natural material that has been widely applied as a low-cost adsorbent for removing various contaminants from wastewater. To improve its characteristics and activity, natural clay from Central Kalimantan was activated by acid and calcination treatments, then synthesized with magnetite (Fe3O4) in nanocomposite by co-precipitation method. The obtained nanocomposite was further characterized by Fourier transform infrared spectroscopy, X-ray diffraction, nitrogen adsorption, vibrating sample magnetometry, and transmission electron microscopy methods. The results showed that co-precipitation method has been successfully produced clay-magnetite nanocomposite from activated clay with specific surface area, saturation magnetization, and particle size were 37.458 m2/g, 24.910 emu/g, and 50 nm, respectively. The obtained natural clay, activated clay, and clay-magnetite nanocomposite were then evaluated for adsorptive removal of naphthol blue black (NBB) synthetic dye from wastewater generated by an industry of Benang Bintik batik in Central Kalimantan using a batch system. The results showed that optimum pH for adsorptive removal process from these adsorbents were 2, while the optimum contact times of natural clay, activated clay, and clay-magnetite nanocomposite were 90, 60, and 60 minutes, respectively. The clay-magnetite nanocomposite also showed a much better removal efficiency (99.58%) than activated clay (86.28%) and natural clay (68.27%). The utilization of clay-magnetite nanocomposite as adsorbent not only can increase its removal efficiency against NBB dye, but also can facilitate the separation of the adsorbent solid phase from wastewater using an external magnetic field after the adsorptive removal process.

Reactive flash sintering of SrFe12O19 ceramic permanent magnets

Reactive flash-sintering technique has been used in order to obtain strontium ferrite magnets from a mixture of SrCO3 and Fe2O3 commercial powders. This technique allows preparing sintered SrFe12O19 at a furnace temperature of just 973 K during just 2 min by applying a modest field of 40 V cm-1, instead of the conventional sintering process employed in ferrite magnet manufacturing that demands high temperature and long dwell times. Analysis of structural and magnetic properties were performed as a function of time in which the flash event was held. Mössbauer spectra show the existence of five different kinds of local environments, confirming the formation of strontium hexaferrite. The resulting samples exhibit comparable magnetic properties to the state-of-the-art ferrite magnets. In particular, produced samples reach a coercivity of 0.4 T and a specific saturation magnetization of 70 Am2 kg-1.

The Structure and ferromagnetism of carbon nanofibers from polyacrylonitrile/ polyvinylpyrrolidone

Room-temperature ferromagnetism was successfully induced in carbon. Carbon nanofibers were fabricated using sequential electrospinning of polyacrylonitrile (PAN) and polyvinylpyrrolidone (PVP). The morphologies, crystal structures, chemical bonding states and magnetic properties were characterized over three different weight ratios which were 10:0, 7:3 and 6:4 of PAN/PVP. The carbon nanofibers obtained after pyrolysis of polymer fibers were placed inside a tube furnace using a three steps process: stabilization, carbonization, and activation at 800℃. XRD patterns indicated the amorphous structure of carbon. The average diameter of the carbon nanofibers was between 340 nm to 511 nm. Raman analysis was used to determine the carbon qualities in the samples by the numbers of sp3/sp2 hybridized atoms. The chemical analysis obtained XPS indicated that there were no magnetic contaminants. The PAN/PVP weight ratio of 6:4 showed ferromagnetic carbon nanofibers with the highest specific saturation magnetization as ~144.2 m-emu×g-1 at 300 K. This indicated that the mixing of sp2-sp3 carbon system had localized magnetic moments. This finding suggests an inexpensive method for preparing magnetic particles and human-friendly ways to produce magnetic material without metals. These results inspire us to further research on the potential of carbon materials, as a completely new class of magnetic devices.

Adsorption performance of red mud magnetic composite material modified by Spirit‐based distillers' grains for low‐concentration phosphorus in water

AbstractBackgroundResearch on phosphate removal has focused on high‐phosphorus wastewater, which has difficulty meeting the discharge standard through one‐step processing. Herein, the rich carbon source of spirit‐based distillers' grains was used to reduce and roast red mud (RM) to prepare magnetic adsorption material (MRM), aiming to improve the adsorption performance of RM on low‐concentration phosphorus in water and to facilitate the separation and recovery of the adsorbent.ResultsThe characterization results of MRM indicated that the high‐temperature decomposition of macromolecular minerals in RM exposed more active sites of metal ions. Compared with unmodified samples, the specific surface area and saturation magnetization of MRM increased by 3.64 and 9.21 times, respectively;this provided more active sites for phosphorus adsorption by MRM and gave the material magnetic separation ability. The results of adsorption experiments showed that MRM had a wide applicable pH range and good selectivity for phosphorus adsorption, and the phosphorus removal rate was 4.97 times that of RM. The adsorption process of phosphorus by MRM was more in line with the Langmuir isotherm adsorption model and the quasi‐second‐order kinetic equation, as it was a process of spontaneous endothermic entropy increase. The phosphorus removal mechanism included chemical precipitation, coordination exchange, physical adsorption, and electrostatic attraction.ConclusionMRM has good adsorption performance for low concentrations of phosphorus in water and provides an effective method for the resource utilization of red mud and spirit‐based distillers' grains. © 2022 Society of Chemical Industry (SCI).

Polyfunctional materials based on ferrites for the treatment of colored wastewater

Problem. Large volumes of metalcontaining wastewater necessitate their processing to obtain new materials. Goal. The goal is obtaining mixed zinc and copper ferrites from spent technological sulfate copper-zinc solutions and to substantiate their technically useful properties. Methodology. Composite materials containing copper-zinc ferrites (FC) were obtained by coprecipitation from spent technological sulfate copper-zinc solutions. The ratio of copper, zinc and iron in ferrites has been determined. Research methods used X-ray phase analysis, electron probe microanalysis, IR spectroscopy, macroelectrophoresis, determination of ferrite magnetization using a ballistic magnetometer, spectrophotometry. Results. Zinc is more fully included in ternary ferrites than copper. It is proved that the surface groups of ferrites are O–H in adsorbed associates and end groups of water, deformation vibrations of the Zn–O–H, Fe–O–H and O–H groups have been recorded. Originality. The specific saturation magnetization of ferrite particles varies in the range of 6– 46 emu/g decreasing with an increase in the proportion of nonmagnetic Zn and Cu. There is no residual magnetization in ferrites. The synthesized ferrites belong to superparamagnets with a particle size of 7‒14 nm. Practical value. FCs are active in the processes of purification of the aqueous phase from the dye methyl violet (MV). For most FCs, cleaning is effective when the mass of ferrite exceeds the mass of MV by 1000 times, when at the same time a high purification efficiency and the degree of conversion of MV per unit of FC mass is achieved. Within 5 hours the solutions can be purified from MV by 99 %. Simultaneous photocatalysis and adsorption is possible. The photocatalytic activity of FCs manifests itself at the beginning of the process, with a further decrease when the FC surface is screened by the MV layer.

Adsorption of doxorubicin on the surface of magnetically sensitive nanocomposite Fe3O4/Al2O3/С

Fe3O4/Al2O3/С nanocomposite was synthesized and characterized by a complex of physicochemical methods. The completeness of carbonization was confirmed by the method of TPD MS, and the results of TEM, EDX and changes in the values of the specific saturation magnetization proved the formation of the structure of Fe3O4/Al2O3/С by the type of core-shell. According to the results of potentiometric studies, the characteristics of acid -basic centers were quantitatively and qualitatively assessed. The adsorption of Doxorubicin (DOX) on the surface of Fe3O4/Al2O3/С was performed and the adsorption process depending on the contact time, pH of the solution and DOX concentration was studied. The experimental results of kinetic studies were analyzed for compliance with of Boyd, Morris-Weber and Elovich the theoretical models, models of pseudo-first and pseudo-second orders. Langmuir and Freundlich isotherm models were used to model adsorption processes. Under the conditions of the experiment (pH = 5) active basic centers (С = 8.46⋅10−5 mol⋅g −1, Кі = 1.296⋅10−5 (рК = 4.887)). Adsorption processes occur by a mixed diffusion mechanism, limiting processes are intraparticle diffusion and chemisorption processes of molecular and ionic forms of DOX. The highest correlation coefficient was r 2 = 0.971, the correlation of theoretical and practical values of the adsorption capacity (A mg g −1) indicates the possibility of using the Freundlich model to describe the adsorption of DOX on the surface of Fe3O4/Al2O3/C. Desorption processes practically do not occur at pH 7.4 (change of value A from 30.56 to 30.12 mg g −1, which is − 1.83%), at pH 5 percent of desorbed DOX is higher − 2.88% (change in value A from 30.21 to 29.51 mg g −1).

Mesoporous LaFeO3 nanoparticles decorated onto activated carbon from agricultural paste (Synthesis, characterization and adsorption properties)

This work reports study of structure, magnetic and adsorption properties of LaFeO3 nano particles decorated on the surface of activated carbon. Activated carbon was prepared from sugar beet residue as an agricultural waste material (ACS). The perovskite-type oxide LaFeO3 nanoparticles were prepared by sol-gel (pechini) method using citric acid. The LaFeO3 was decorated on the surface ACS. The structure of samples was studied by Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET). The surface morphology was considered by field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS) methods. The XRD results showed LaFeO3 nanoparticles have orthorhombic structure (space group continued to be Pnma. No. 62) of LaFeO3 perovskite did not change even when it was decorated onto ACS. VSM vibrating of samples was determined. The weak ferromagnetic behavior with specific saturation magnetization of 1.18 and 0.6 emu/g was observed at 15 kOe for LaFeO3 and LaFeO3 nanoparticles decorated onto ACS, respectively. Crystal violet (CV) dye was used as a model of pollutant. At contact time of 60 min and pH of 7 the highest percent of CV was observed. The maximum adsorption capacities of CV removal by ACS, LaFeO3 and LaFeO3 decorated on ACS was obtained, respectively. The adsorption kinetic of CV removal was followed by pseudo-second order model. Thermodynamic parameters of adsorption process of CV showed the endothermic and spontaneous processes. The LaFeO3 was decorated on the ACS was examined for real wastewater and 75% of dye removal was obtained.