Efficient Magnetic Separation Research Articles

Enhanced photodegradation of reactive dyes in textile effluent with CoFe2O4/g-CN heterostructure-mediated peroxymonosulphate activation.

Graphitic carbon nitride (g-C3N4) was employed as a sacrificial substructure and two-dimensional support to develop magnetic cobalt ferrite-carbon nitride (CoFe2O4/g-CN) composite via a one-step solid combustion method. The catalyst activated peroxymonosulphate (PMS), through the interconversion of Co2 + /3+|surf. and Fe2 + /3+|surf. on its surface for degradation of reactive dyes (RDs). Excellent ferromagnetic nature (44.15 emu g-1) of the catalyst led to its efficient magnetic separation. With an optimum catalyst and PMS dose of 0.4 g L-1 and 1.5 g L-1, 99% RD removal was achieved for textile effluent (pH 9.5-10), under UV irradiation (48 W). In-depth radical scavenging experiments and EPR analysis confirmed the dominance of radical-based degradation process. Plausible degradation and mineralization pathways of RDs were proposed through identification of intermediates by LCMS/MS analysis. In brief, this study elucidates an exclusive strategy towards the use of g-C3N4 as fuel for facile synthesis of magnetic CoFe2O4/g-CN as a remarkable photocatalyst for activation of PMS towards mineralization of various industrially relevant RDs.

3D printing of NiZn ferrite architectures with high magnetic performance for efficient magnetic separation

Magnetic materials with desired architectures and high performance have become increasingly important for applications. In this work, NiZn ferrites with mesh structures have been successfully fabricated from preliminary precursors by three-dimensional (3D) printing accompanied by the solid-state reaction. The influence of compositions on structural and magnetic properties of NiZn ferrites were systematically investigated. It was obvious that the saturation magnetization was significantly enhanced to 77 emu/g for NiZn ferrites with a zinc concentration of 0.4, which was a much higher value compared to Ni ferrites. This is attributed not only to the well-known cationic distribution, but also to the grain growth with extraordinarily high crystallinity. Consequently, NiZn ferrites with intricate mesh structures were utilized for magnetic separation, and the distributions of magnetic flux density were simulated. Overall, the fabrication of NiZn ferrites by 3D printing is attractive for scaled-up applications, and also paves the promising avenue for magnetic separation.

Efficient production of biodiesel with electric furnace dust impregnated in Na2CO3 solution

Solid catalyst (Na2CO3@EFD) was prepared by wet impregnation of electric furnace dust (EFD) in aqueous Na2CO3 solution. It had high basicity and acidity of 0.34 and 0.16 mmol/g for biodiesel production. High biodiesel yield of 99.8 wt% from soybean oil was obtained under the optimized reaction conditions (by Central Composite Design) of 71 °C in 111.36 min with 5.4 wt% catalyst and methanol/oil molar ratio of 11.8/1. After 11 cycles, biodiesel yield still maintained at 90.8 wt% with catalyst recovery rate >90 wt% by magnetic separation of catalyst EFD powders (containing Fe3O4 with magnetism of 59.1 Am2/kg). Pure Na2CO3 particles presented poorer recyclability with lower biodiesel yield of 89.5 wt% even at the eighth cycle by centrifugal separation. Na2CO3@EFD catalyst had high activity and recyclability because: (i) EFD as support hosted nanoparticles of Na2CO3 (30.3 nm) as main base site for transesterification; (ii) porous EFD support provided acidic sites from metal oxides (e.g., ZnO and Al2O3) for esterification; (iii) EFD adsorbed active components into its micropores to maintain high recyclability; and (iv) EFD magnetism from magnetic Fe3O4 kept high efficient magnetic separation. Total metals in the blended biodiesel met the National Standard of China and heavy metals were lower than typical petrochemical diesel. The study gave a practical use of industrial solid waste for the green production of biodiesel.

Retraction Note to: Amine functionalized magnetic nanoparticles for removal of oil droplets from produced water and accelerated magnetic separation

Magnetic nanoparticles (MNPs) with surface coatings designed for water treatment, in particular for targeted removal of contaminants from produced water in oil fields, have drawn considerable attention due to their environmental merit. The goal of this study was to develop an efficient method of removing very stable, micron-scale oil droplets dispersed in oilfield produced water. We synthesized MNPs in the laboratory with a prescribed surface coating. The MNPs were superparamagnetic magnetite, and the hydrodynamic size of amine functionalized MNPs ranges from 21 to 255 nm with an average size of 66 nm. The initial oil content of 0.25 wt.% was reduced by as much as 99.9% in separated water. The electrostatic attraction between negatively charged oil-in-water emulsions and positively charged MNPs controls, the attachment of MNPs to the droplet surface, and the subsequent aggregation of the electrically neutral oil droplets with attached MNPs (MNPs-oils) play a critical role in accelerated and efficient magnetic separation. The total magnetic separation time was dramatically reduced to as short as 1 s after MNPs, and oil droplets were mixed, in contrast with the case of free, individual MNPs with which separation took about 36∼72 h, depending on the MNP concentrations. Model calculations of magnetic separation velocity, accounting for the MNP magnetization and viscous drag, show that the total magnetic separation time will be approximately 5 min or less, when the size of the MNPs-oils is greater than 360 nm, which can be used as an optimum operating condition.

Dispersive magnetic solid phase microextraction on microfluidic systems for extraction and determination of parabens

In this study, a customized microfluidic system was utilized for magnetic solid phase extraction of parabens. For this sake, magnetite nanoparticles were synthesized and coated with polyaniline to enable efficient extraction and magnetic separation of sorbents particles. The synthesized particles were extensively characterized in terms of morphology, composition, and magnetic properties. The utilized microfluidic platform consisted of a relatively long spiral microchannel fabricated through laser-cutting and multi-layered assembly. To obtain an efficient dispersion, simultaneous flows of sample solution and magnetic beads dispersion were introduced to the chip with the aid of two syringe pumps. In order to increase the stability of the dispersed nanoparticles in the aqueous solution, various chemical and instrumental parameters were investigated and optimized. In this context, exploitation of hydrophobic surfactants and surface charge manipulation of the particles was shown to be a highly promising approach for effective dispersion and maintenance of magnetic beads in long microfluidic channels. Under the optimized conditions, the calibration curves were linear in the range of 5.0–1000.0 μg L−1 for propyl paraben and 8.0–1000.0 μg L−1 for methyl- and ethyl paraben with coefficients of determination greater than 0.992. Relative standard deviations were assessed as intra- and inter-day values which were less than 7.2% and the preconcentration factors in water were 10–15 for 100 μg L−1 of parabens in water. Finally, the method was applied for the extraction of parabens from fruit juice, sunscreen, and urine samples which showed favorable accuracy and precision.

Preparation of diatomite supported calcium ferrite ternary magnetic material and its adsorption of selenite in aqueous solution

In this study, ternary magnetic materials (Dt@CaFe2O4@Fe3O4(Dt@CF@F)) were prepared via sintering method for selenite removal from aqueous solution, and under the optimized conditions, the maximum adsorption capacity of selenite reached 116.14 mg g−1. Based on the analysis of SEM, BET, XRD, XPS and FTIR, a proposed adsorption mechanism of Se(Ⅳ) by Dt@CF@F included inner layer complexation, electrostatic adsorption, and reduction reactions. Experimental results of adsorption isotherms revealed that the adsorption was chemisorption and monolayer adsorption. And results of thermodynamics indicated that Se (IV) adsorption was a spontaneously endothermic process. The results of coexisting ions experiment showed that the existence of Na+, K+, Mg2+, Ca2+ and coexisting anions such as Cl- and NO3- had insignificant effects on Se (IV) adsorption, whereas SO42− and PO43− exhibited a significant effect. The results of VSM analysis exhibited that Dt@CF@F has strong magnetic responsiveness, which is favorable for its efficient and facile magnetic separation. Furthermore, the adsorbent remained a high activity after 10 consecutive regeneration cycles, with the removal rate of Se (IV) decreased from 99.18% to 84.64%. Therefore, the synthesized Dt@CF@F adsorbent with high adsorption capacity, convenient magnetic separation, environmental friendliness, excellent stability and reusability has a great potential for the application of Se (IV) removal from aqueous solution.

Synthesis of magnetic activated carbons from black liquor lignin and Fenton sludge in a one-step pyrolysis for methylene blue adsorption

Black liquor lignin and Fenton sludge were used to prepare magnetic activated carbons (MACs) by one-step pyrolysis using KOH as an effective activator. Brunauer-Emmett-Teller (BET) analysis showed that the addition of Fenton sludge increased the mesopore volume of MACs compared with the control AC, and the addition of KOH not only improved the porosity but also enhanced the formation of high ferromagnetic particles (α-Fe). X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) analysis revealed that the iron-based materials in the MACs were Fe3O4 and α-Fe nanoparticles, indicating good magnetic properties. The textural properties and the magnetic properties of the MACs can be modified by controlling the Fenton sludge/lignin ratio. The adsorption process of MAC0.5–2 (mFenton sludge: mlignin: mKOH=0.5:1:2) and MAC1–2 (mFenton sludge: mlignin: mKOH=1:1:2) were investigated. The two MACs exhibited good adsorption capacity (qMAC0.5−2= 307.2 mg g−1 and qMAC1−2= 184.1 mg g−1) for methylene blue (MB) dye. The adsorption kinetics of MB dye onto two MACs followed the pseudo-second order model and the equilibrium data was fitted best with the Sips isotherm model. The thermodynamic study revealed that the adsorption process was endothermic and spontaneous in nature. The recovery efficiency of MAC0.5–2 and MAC1–2 remained 84.0% and 92.1% respectively after five-cycle adsorption-desorption. The synthesized MACs with high magnetic separation efficiency, good recovery ability, and high adsorption efficiency can be promising and effective adsorbents for MB dye or other dyes.

Bioengineered Polymer Nanobeads for Isolation and Electrochemical Detection of Cancer Biomarkers.

Early sensitive diagnosis of cancer is critical for enhancing treatment success. We previously bioengineered multifunctional core-shell structures composed of a poly-3-hydroxybutyrate (PHB) core densely coated with protein functions for uses in bioseparation and immunodiagnostic applications. Here, we report bioengineering of Escherichia coli to self-assemble PHB inclusions that codisplay a ferritin-derived iron-binding peptide and the protein A-derived antibody-binding Z domain. The iron-binding peptide mediated surface coating with a ferrofluid imparting superparamagnetic properties, while the Z domain remained accessible for binding of cancer biomarker-specific antibodies. We demonstrated that these nanobeads can specifically bind biomarkers in complex mixtures, enabling efficient magnetic separation toward enhanced electrochemical detection of cancer biomarkers such as methylated DNA and exosomes from cancer cells. Our study revealed that superparamagnetic core-shell structures can be derived from biological self-assembly systems for uses in sensitive and specific electrochemical detection of cancer biomarkers, laying the foundation for engineering advanced nanomaterials for diverse diagnostic approaches.

Scaled-up development of magnetically recyclable Fe3O4/La(OH)3 composite for river water phosphate removal: From bench-scale to pilot-scale study

The use of magnetic lanthanum-based materials for phosphate removal from river water has gained increasing attention. However, challenges to produce and use lanthanum-based materials in large-scale or pilot-scale studies remain. In this work, a kilogram-scale Fe3O4/La(OH)3 magnetically recyclable composite for removing phosphate from river water was developed through a low-temperature precipitation route. The composite was used to remove phosphate from river water at both bench- and pilot-scales. Based on the bench-scale tests, the developed Fe3O4/La(OH)3 composite was found to have excellent magnetic particle separation efficiency (>98%) and a sorption capacity of 11.77 mg/g for phosphate. A 1.0 g/L dosage of the composite in the river water sample was able to selectively reduce the phosphate level from 0.089 to 0.005 mg/L in 60 min over five consecutive adsorption cycles. At the pilot-scale, the Fe3O4/La(OH)3 composite only achieved 36.0% phosphate removal efficiency, which is considerably different from the bench-scale results over an operational time of five months and a total treatment volume of 300 m3. This significantly reduced removal efficiency is mainly attributable to turbidity, suspended solids, and organic matter in the river water and the deteriorated magnetic separation efficiency. This study revealed potential challenges and shed new insights on moving magnetic nanocomposite-based technology from the bench-scale to the pilot-scale, which can inspire new designs for the application of similar technology.

Magnetic Separation of Antibodies with High Binding Capacity by Site-Directed Immobilization of Protein A-Domains to Bare Iron Oxide Nanoparticles

The demand for purified antibodies is ever-rising. This study presents a nanoparticle-based material for efficient magnetic separation of immunoglobulin G (IgG) with high binding capacity. The char...

Effect of microwave radiation on the magnetic properties of ludwigite and iron-boron separation

To effectively separate and recover the valuable elements iron and boron from ludwigite, this study investigated the magnetic properties and the magnetic separation efficiency. And the reactivity of boron component in the B-bearing tailing was studied. The results indicated that the saturation magnetization of ore samples was increased with the increase of microwave power and heating time. Under condition of 40 s with 4 kW, the saturation magnetization of ore samples increased from 12.73 emu/g for the raw ore to 24.70 emu/g for the treated ore, an increased of 94.03%. After magnetic separation, the grade and recovery rate of iron in the iron concentrate and the boron grade in the tailing for the treated sample with 4 kW for 40 s were increased by 19.74%, 31.46% and 86.46% in comparison with those of the untreated ore. The sample was heated to 600 °C at 4 kW and held for 20 min, the reactivity of boron component in the B-bearing tailing reached 86.68 wt%, which increased by 34.01% compared with that of the raw ore and 4.43% compared with that of the optimal traditional roasting value at 700 °C for 2 h, indicating that the roasting temperature and time were obviously decreased and the reactivity was significantly improved by the microwave radiation.

Study on Magnetic Porous Carbon Microspheres as a Novel Adsorbent for Malachite Green

AbstractIn this paper, a novel adsorbent of magnetic mesoporous carbon microspheres (MCS) are prepared by template methods and using nano‐Fe3O4 particles as magnetic cores, and the adsorption capacity and mechanism are studied in detail. The results show that MCS exhibits high performance for removing malachite green (MG), the highest adsorption capacity can reach about 468.5 mg g−1. Furthermore, the Langmuir adsorption isotherm model and the quasi‐second‐order kinetic model can explain the experimental phenomena very well. And the high adsorption capacity of MCS is mainly attributed to its unique mesoporous structure by increasing the specific surface area and providing sufficient active sites. In addition, after magnetic separation and recovery, MCS can be regenerated with ethanol. And MCS maintains a high adsorption rate of 84.5 % after 5 cycles of MG adsorption and desorption. This composite material with high adsorption efficiency and rapid magnetic separation is a promising recyclable adsorbent for the actual wastewater treatment and purification process.

Comparative Study of CoFe2O4 Nanoparticles and CoFe2O4-Chitosan Composite for Congo Red and Methyl Orange Removal by Adsorption.

(1) Background: A comparative research study to remove Congo Red (CR) and Methyl Orange (MO) from single and binary solutions by adsorption onto cobalt ferrite (CoFe2O4) and cobalt ferrite–chitosan composite (CoFe2O4-Chit) prepared by a simple coprecipitation method has been performed. (2) Methods: Structural, textural, morphology, and magnetic properties of the obtained magnetic materials were examined by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, N2 adsorption–desorption analysis, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and magnetic measurements. The optimal operating conditions of the CR and MO removal processes were established in batch experiments. The mathematical models used to describe the processes at equilibrium were Freundlich and Langmuir adsorption isotherms. (3) Results: Cobalt ferrite–chitosan composite has a lower specific surface area (SBET) and consequently a lower adsorption capacity than cobalt ferrite. CoFe2O4 and CoFe2O4–Chit particles exhibited a superparamagnetic behavior which enabled their efficient magnetic separation after the adsorption process. The research indicates that CR and MO adsorption onto prepared magnetic materials takes place as monolayer onto a homogeneous surface. According to Langmuir isotherm model that best fits the experimental data, the maximum CR/MO adsorption capacity is 162.68/94.46 mg/g for CoFe2O4 and 15.60/66.18 mg/g for CoFe2O4–Chit in single solutions. The results of the kinetics study revealed that in single-component solutions, both pseudo-first-order and pseudo-second-order kinetics models represent well the adsorption process of CR/MO on both magnetic adsorbents. In binary solutions, adsorption of CR/MO on CoFe2O4 better follows the pseudo-second-order kinetics model, while the kinetic of CR/MO adsorption on CoFe2O4–Chit is similar to that of the dyes in single-component solutions. Acetone and ethanol were successfully used as desorbing agents. (4) Conclusions: Our study revealed that CoFe2O4 and CoFe2O4–Chit particles are good candidates for dye-contaminated wastewater remediation.

Investigation of the Influence of Ultrafine Grinding and Ultrasonic Field on the Intensification of the Processes of Extraction of Iron Oxides from Ash and Slag Waste of Energy

The possibility of extracting iron oxides from ash and slag wastes of the Primorskaya GRES power plant - (Luchegorsk, Primorsky Kray) was investigated. The positive influence of the energy of ultrasonic vibrations with frequency of 22 kHz and power at1 kW, on the increase in the percentage of extraction of iron from ash and slag waste from thermal power is presented. The optimal time of exposure to ultrasound radiation on ash and slag pulp is determined. A comparison of the magnetic separation of ash and slag waste (ASW) without additional grinding with magnetic separation with preliminary grinding of sample materials down to 90 and 40 microns is carried out. The positive effect of preliminary grinding of the ASW sample on the efficiency of the subsequent magnetic separation is presented. With double magnetic separation of the ASW sample in a magnetic field of 300 T and preliminary crushing of the sample to a particle size class of less than 40 microns, a concentrate was obtained with an iron oxide content of 52.9; the extraction rate of iron oxides equaled 84.2%.

Recent development of magnetic nanomaterial-supported M(Salen) composites as recyclable heterogeneous catalysts

Metal complexes of Salen-type ligands [M(Salen)] were widely used as catalysts with high activity for coupling reactions, addition reactions and epoxidation reactions. However, homogeneous catalysts based on M(Salen) complexes are difficult to separate and recover. Therefore, it is of great significance to find suitable supports to support M(Salen) complexes and obtain composites as separable and recyclable heterogeneous catalysts. Magnetic nanomaterials, which is widely researched as an inorganic nanosupports, are advantageous for the preparation of supported M(Salen) catalysts due to their characteristics of magnetic separation, good chemical stability and easy functionalization. In this review, research works on many types of the magnetic nanomaterial-supported M(Salen) catalysts, especially their preparations and applications as heterogeneous catalysts are discussed in detail. In addition, the advantages and disadvantages of different magnetic nanomaterials-supported M(Salen) composites are described, and some recommendations and references are provided for structure design of magnetic nanomaterial-supported M(Salen) catalyst with improved magnetic separation and catalytic efficiency. At last, limitations of magnetic nanomaterial-supported M(Salen), including structural instability, tedious multistep reactions and difficulty in industrial production, are discussed and their applications as heterogeneous catalysts are prospected.

Magnetophoresis of Magnetic Pickering Emulsions Under Low Field Gradient: Macroscopic and Microscopic Motion.

Monodispersed iron oxide nanoparticles (IONPs) coated with polystyrenesulfonate (PSS) and cetrimonium bromide (CTAB) have been used to stabilize magnetic Pickering emulsions (MPEs). Magnetophoresis of MPEs under the influence of a low gradient magnetic field (∇B < 100 T/m) was investigated at the macroscopic and microscopic scale. At the macroscopic scale, for the case of pH 7, the MPE achieved a magnetophoretic velocity of 70.9 μm/s under the influence of ∇B at 93.8 T/m. The magnetic separation efficiency of the MPE at 90% was achieved within 30 min for pH 3, 7, and 10. At pH 10, the colloidal stability of the MPE was the lowest compared to that for pH 3 and 7. Thus, MPE at pH 10 required the shortest time for achieving the highest separation efficiency, as the MPE experienced cooperative magnetophoresis at alkaline pH. The creaming rate of the MPE at all conditions was still lower compared to magnetophoresis and was negligible in influencing its separation kinetics profiles. At the microscopic scale, the migration pathways of the MPEs (with diameters between 2.5 and 7.5 μm) undergoing magnetophoresis at ∇B ∼ 13.0 T/m were recorded by an optical microscope. From these experiments, and taking into consideration the MPE size distribution from the dynamic light scattering (DLS) measurement, we determined the averaged microscopic magnetophoretic velocity to be 7.8 ± 5.5 μm/s. By making noncooperative magnetophoresis assumptions (with negligible interactions between the MPEs along their migration pathways), the calculated velocity of individual MPEs was 9.8 μm/s. Such a value was within the percentage error of the experimental result of 7.8 ± 5.5 μm/s. This finding allows for an easy and quick estimation of the magnetophoretic velocity of MPEs at the microscale by using macroscopic separation kinetics data.

Spinel ferrite transformation for enhanced upgrading nickel grade in laterite ore of various types

Upgrading nickel grade in low-grade nickeliferous laterite ores before metallurgical extraction process is of utmost importance. However, most of nickel exists mainly in the form of isomorphism in serpentine or goethite, resulting in difficulty in upgrading of nickel by physical separation methods. In this paper, spinel ferrite transformation for enhanced upgrading nickel grade in laterite ore of various types was proposed. The mineral phase transformation and migration of valuable metals for various laterite ores during calcination process was investigated, as well the influences of mineral phases and chemical compositions on magnetic properties, separation efficiency, and nickel contents in separated laterite ore. The results show that spinel nickel ferrite mainly composed of nickel oxide and iron oxide could be completely formed after calcined at 800, 1000 and 900 °C for limonite, saprolite and transition laterite ore, respectively. With the increase of calcination temperature, the crystallinity and saturation magnetization Ms value of as-calcined samples become improved, leading to increased nickel recovery, while the nickel content in magnetic fraction is first increased and then slightly decreased. Under the optimum calcination conditions, the nickel recovery for limonite, saprolite and transition laterite ore could reach 68.5%, 68.9% and 67.3%, respectively, while the nickel contents in magnetic fraction are 3.01%, 3.23% and 3.15% with increasing by 1.82, 2.27 and 2.11 times, respectively. This paper could provide theoretical basis and technology support for enhanced upgrading of valuable metals from complex associated mineral resources.

Fabrication of ferrihydrite-loaded magnetic sugar cane bagasse charcoal adsorbent for the adsorptive removal of selenite from aqueous solution

Herein we report the fabrication of ferrihydrite-loaded magnetic sugar cane bagasse charcoal adsorbent (FH@Fe3O4@SCBC) by in-situ growth method, which was in turn applied for the adsorptive removal of Se(IV) from aqueous solution. The prepared adsorbents were characterized by SEM-EDS, BET, XRD, VSM, FT-IR, and XPS analyses, and the effect of reaction temperature and pH on Se(IV) removal rate was investigated. Experimental results revealed that the maximum concentration of released Fe ions (0.20 mg L−1) was lower than the WHO highest authorized standard value for Fe in drinking water (0.30 mg L−1) indicating that FH@Fe3O4@SCBC adsorbent has good stability. Experimental results of adsorption kinetics and isotherms revealed that adsorption of Se(IV) by FH@Fe3O4@SCBC mainly occurred via chemisorption and monolayer adsorption and the maximum theoretical adsorption capacity Se(IV) was 95.15 mg g−1. The experiment on the coexisting anions showed that SO42− and PO43− exhibited a significant effect on the adsorption process of Se(IV) while Cl− and NO3− exhibited an insignificant effect. A proposed adsorption mechanism showed that Se(IV) removal included FH@Fe3O4@SCBC inner-sphere complexation, electrostatic interaction, and reduction reaction. According to VSM analysis, FH@Fe3O4@SCBC showed enhanced magnetic response thus facilitating its efficient and facile magnetic separation. Furthermore, FH@Fe3O4@SCBC realized minimal loss in adsorption activity (decreased by 11.5 %) after 10 consecutive reuses. This study provides a facile and cost-effective approach for the fabrication of highly stable FH@Fe3O4@SCBC adsorbent with high adsorption capacity, fast magnetic separation, and excellent recycling advantages making it a promising material for the remediation of Se(IV) from wastewater.

The efficient magnetic separation of the four biogenic nanoparticles from aqueous media by the unmodified iron oxide nanoparticles

By release of nanoparticles with toxic potentials into environment, there is an urgent need for development of keen procedures for their removal. In this research, unmodified iron oxide nanoparticles were applied for the separation of the Ag/AgCl nanoparticles, Ag nanoparticles, Ag–Cu nanoparticles and Cu nanoparticles from the aqueous environment. The samples were subjected to different characterization and spectroscopic analyses before and after being exposed to magnetic separation. Scanning electron microscopy/energy-dispersive x-ray spectroscopy analysis showed the attachment of the biogenic nanoparticles onto the magnetic nanoparticles which were observed by the obvious shift in the color and the turbidity between the sample and its control. The Ag and Cu contents of the separated nanoparticles were measured by inductively coupled plasma mass spectrometry, presenting the highest recovery efficiency for Ag–Cu nanoparticles (96%). However, the other rest of the nanoparticles were trapped by a removal efficiency of more than 80%. When compared to the previous studies, the efficiency of this method was among the highest ones. The ability of this type of the magnetic nanoparticles for the adsorption of the biogenic nanoparticles enunciates them as a fast, green, convenient and keen tool for trapping and the removal of the biogenic nanoparticles from an aqueous media.

Increasing efficiency of iron ore magnetic separation by using ultrasonic technologies

The research is aimed at solving the topical problem of enhancing efficiency of iron ore magnetic separation by applying ultrasonic technologies to identify optimal technological parameters of magnetic separation, improving controlled structural parameters of a magnetic separator and pretreating slurry by highenergy ultrasound to clean the ore material surface from fine-dispersed particles of minerals and slime, as well as disintegrate ore aggregates fed to the magnetic separator. The main tasks involve identifying regularities of influence of slurry pretreatment by high-energy ultrasound on properties of iron ore magnetic separation, determining regulations of improving technological and controlled structural parameters of the magnetic separator using ultrasonic methods, developing and substantiating methods to enhance efficiency of iron ore magnetic separation by applying ultrasonic technologies.