Efficient Magnetic Separation Research Articles

Magnetic separation, sunlight-driven photocatalytic activity, and antibacterial studies of Sm-doped Co0.33Mg0.33Ni0.33Fe2O4 nanoparticles.

Magnetic nanoparticles have emerged as a promising tool for wastewater treatment due to their unique properties. In this regard, Co0.33Mg0.33Ni0.33SmxFe2-xO4 (0.00 x 0.08) nanoparticles were prepared to examine their magnetic separation efficiency (MSE), photocatalytic, antibacterial, and antibiofilm performances. Pure nanoparticles, having the highest saturation magnetization (Ms = 31.87emu/g), exhibit the highest MSE, where 95.6% of nanoparticles were separated after 20min of applying a magnetic field of 150 mT. The catalytic performance of the prepared samples is examined by the photodegradation of rhodamine B (RhB) dye exposed to direct sunlight radiation. Improved photocatalytic activity is exhibited by Co0.33Mg0.33Ni0.33Sm0.04Fe1.96O4 nanoparticles, labeled as Sm0.04, where the rate of the degradation reaction is enhanced by 4.1 times compared to pure nanoparticles. Rising the pH and reaction temperature improves the rate of the photodegradation reaction of RhB. The incorporation of 15 wt% reduced graphene oxide (rGO) with Sm0.04 enhanced the rate of the reaction by 1.7 and 2.4 times compared with pure Sm0.04 sample and rGO, respectively. The antibacterial and antibiofilm activities against Escherichia coli, Leclercia adecarboxylata, Staphylococcus aureus, and Enterococcus faecium are assessed by the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) broth microdilution, the agar well diffusion, the time-kill assays, the biofilm formation, and destruction assays. The bacteria used in these assessments are isolated from wastewater. The nanoparticles exhibit a bacteriostatic activity, with a better effect against the Gram-positive isolates. Co0.33Mg0.33Ni0.33SmxFe2O4 (x = 0.00) nanoparticles have the best effect. The effect is exerted after 2-3h of incubation. Gram-positive biofilms are more sensitive to nanoparticles.

Direct Affinity Ligand Immobilization onto Bare Iron Oxide Nanoparticles Enables Efficient Magnetic Separation of Antibodies.

Magnetic separation is a promising alternative to chromatography for enhancing the downstream processing (DSP) of monoclonal antibodies (mAbs). However, there is a lack of efficient magnetic particles for successful application. Aiming to fill this gap, we demonstrate the suitability of bare iron oxide nanoparticles (BION) with physical site-directed immobilization of an engineered Protein A affinity ligand (rSpA) as an innovative magnetic material. The rSpA ligand contains a short peptide tag that enables the direct and stable immobilization onto the uncoated BION surface without commonly required laborious particle activation. The resulting BION@rSpA have beneficial characteristics outperforming conventional Protein A-functionalized magnetic particles: a simple, fast, low-cost synthesis, a particle size in the nanometer range with a large effective specific surface area enabling large immunoglobulin G (IgG) binding capacity, and a high magnetophoretic velocity advantageous for fast processing. We further show rapid interactions of IgG with the easily accessible rSpA ligands. The binding of IgG to BION@rSpA is thereby highly selective and not impeded by impurity molecules in perfusion cell culture supernatant. Regarding the subsequent acidic IgG elution from BION@rSpA@IgG, we observed a hampering pH increase caused by the protonation of large iron oxide surfaces after concentrating the particles in 100 mM sodium acetate buffer. However, the pH can be stabilized by adding 50 mM glycine to the elution buffer, resulting in recoveries above 85% even at high particle concentrations. Our work shows that BION@rSpA enable efficient magnetic mAb separation and could help to overcome emerging bottlenecks in DSP.

Effect of blunging process on purification of halloysite ore from ferrous impurities by dry magnetic separation

The objective of this research is to study the effects of feed particle size, splitter angle, and washing process on Fe<sub>2</sub>O<sub>3</sub> removal efficiency in the separation of ferrous impurities from halloysite ore by dry magnetic separation in order to increase the purity of halloysite sample after crushing and blunging processes separately. Firstly, after crushing ore in a jaw crusher and sizing to -2+1 mm, -1+0.5 mm, and -0.5+0.212 mm fractions, the sized materials were fed to REMS-type dry magnetic separator at a constant belt speed of 300 rpm with the splitter angles of 0, 15, 30º separately. Maximum Fe<sub>2</sub>O<sub>3</sub> removal efficiency (FRE) (97.1%) was obtained in the nonmagnetic product at -0.5+0.212 mm size fraction and 0º splitter angle. The minimum Fe<sub>2</sub>O<sub>3</sub> content (1.3%) was reached in the nonmagnetic product obtained in the experiment with the feed size of -2+1 mm and a splitter angle of 0º. Secondly, dry magnetic separation was applied to the washed -2+0.212 mm size fraction after drying at room temperature to evaluate the coarse particle-sized halloysite ore that was gained by mechanical dispersion in the aqueous medium towards sodium hexametaphosphate (SHMP), while a significant part of the clay minerals went into fine size after the dispersion process. In the experiment performed with a 0º splitter angle after washing, it was determined that halloysite concentrate of 0.4% Fe<sub>2</sub>O<sub>3</sub> content could be obtained with 98.8% Fe<sub>2</sub>O<sub>3</sub> removal efficiency. As a result of dry magnetic separation experiments, it was seen that Fe<sub>2</sub>O<sub>3</sub> removal efficiency decreased as the splitter angle increased, while Fe<sub>2</sub>O<sub>3</sub> content in magnetic and nonmagnetic products increased. It was determined that washing and cleaning of fine-sized minerals plastered on particle surfaces after mechanical dispersion and particle release of minerals with different magnetic properties increased the dry magnetic separation efficiency, and nonmagnetic products with very low Fe<sub>2</sub>O<sub>3</sub> (0.4%) and high Al<sub>2</sub>O<sub>3</sub> (31.9%) content was obtained. The blunging process in the presence of dispersant caused the dispersion of clay minerals and allowed to liberating of the ferrous minerals from the halloysite ore, hence the increase in the FRE for the magnetic separation.

Recovery and regeneration of water-hardened magnetic composite biochar sphere for the removal of multiple heavy metals in contaminated soils

Biochar has exceeded expectations for immobilizing heavy metals (HMs), but the potential ecological risks of its long-term burial in soil limit its practical application on a large scale. To address this challenge, a novel separable water-hardened magnetic composite biochar sphere (WMBCS) was prepared and applied to remediate agricultural soils contaminated with Cd, Pb, and As. The first application of WMBCS is simultaneously effective in removing Cd (3.2–12.7%), Pb (3.3–13.1%), and As (5.0–25.6%) from soil, and the removal rates are enhanced with increasing soil moisture, application dose and incubation time. WMBCS is more efficient for removing Cd and Pb in mildly contaminated alkaline soils than in heavily contaminated acidic soils. Compared with other regeneration methods, shaking and ultrasound-assisted EDTA-2Na efficiently elutes HMs with a dissolution efficiency of over 75% within 4 h, accompanied by the lowest rate of mass loss (7.6%) and Fe leaching (475.1 mg kg−1). After 5 rounds of successive cyclic remediation, WMBCS exhibits high adsorption efficiency (26.5–30.6% for Cd, 25.4–30.2% for Pb, and 30.2–41.0% for As), magnetic separation efficiency (98.8–99.8%) and regeneration efficiency (92.3–95.4%). The main mechanisms involved in the adsorption and regeneration of WMBCS include ion exchange and chelation. WMBCS is an economical and eco-friendly material with vast unexplored potential for use in agriculture.

An air-fluidized magnetic separator and its separation performance for steel slag

In order to address the issue of magnetic agglomeration leading to poor magnetic separation efficiency and low activity enhancement, resulting in limited utilization of steel slag fine powder material, this study proposes a novel dry magnetic separator with air fluidization as the feeding method. The new separator incorporates adjustable magnetic field strength based on the material’s magnetic properties, enabling individual particle separation through a magnetic mesh while simultaneously enhancing mechanical and ultrasonic composite vibration. In addition, it enhances competitiveness by incorporating negative pressure suction. Primary magnetic separation tests on a steel slag fine powder material demonstrate that the air fluidized dry magnetic separator effectively separates inert minerals from active minerals in the steel slag powder. The iron grade in the magnetic products reaches 21.81%, which is 6.88% higher than that of the original steel slag, while the iron grade in non-magnetic products decreases to 11.93%, representing a 3% reduction compared to the original steel slag composition. Further sweeping and selection processes are expected to further improve these results, ultimately achieving effective utilization of steel slag.

Preparation of magnetic DTPA-modified chitosan composite microspheres for enhanced adsorption of Pb(II) from aqueous solution

In this study, magnetic DTPA-modified chitosan composite microspheres (MDCM) were prepared by reverse emulsion-double crosslinking method (carbodiimide followed by glutaraldehyde) for removal of Pb(II) from aqueous solution. The obtained magnetic adsorbents were characterized by FTIR, SEM, XRD, VSM, BET, and 13C NMR. The effects of the pH, contact time, initial concentration, and competitive metal cations (Na(I), Ca(II), or Mg(II)) on Pb(II) adsorption were investigated. The results revealed that MDCM exhibited high removal performance over a wide pH range and in the presence of competitive metal cations. The maximum adsorption capacity of MDCM for Pb(II) is 214.63 mg g−1 at pH 3, which is higher than most recently reported magnetic adsorbents. Adsorption kinetics and isotherms can be described by the pseudo-second-order model and Langmuir model, respectively. In addition, MDCM is easy to regenerate and can be reused five cycles with high adsorption capacity. Finally, the adsorption mechanism was further revealed by FTIR and XPS analysis. Overall, MDCM has practical application potential in removing Pb(II) from contaminated wastewater due to its high adsorption efficiency, good reusability, and convenient magnetic separation.

Fabrication and characterization of magnetic mesoporous nanoparticles for efficient determination and magnetic separation of sulfonamides in food samples.

A magnetic, mesoporous core/shell structured Fe3O4@SiO2@mSiO2 nanocomposite was synthesized and employed as a magnetic solid phase extraction (MSPE) sorbent for the determination of trace sulfonamides (SAs) in food samples. The synthesized nanocomposite was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, X-ray diffraction, N2 sorption analysis and vibrating sample magnetometry. The results showed that Fe3O4@SiO2@mSiO2 possessed a mesoporous structure with a large surface area. Batch experiments were carried out to investigate the adsorption ability for SAs. Fe3O4@SiO2@mSiO2 showed fast kinetics and high adsorption capacity, and the pseudo-second-order model and Langmuir adsorption isotherm are well fitted with the experimental data, indicating that chemical adsorption might be the rate-limiting step. Moreover, the high adsorption capacity can be maintained for at least 8 runs, indicating excellent stability and reusability. The proposed method exhibited good linearity in the range of 0.2-500 μg L-1, the R2 values of all the analytes were greater than 0.99 and the LODs were all lower than 0.2 μg L-1. Furthermore, real food samples were successfully analyzed with Fe3O4@SiO2@mSiO2 and high recoveries varying from 89.7% and 110.6% were obtained with low relative standard deviations ranging from 1.78% to 6.91%. The Fe3O4@SiO2@mSiO2 magnetic nanocomposite is a promising sorbent for the efficient extraction of SAs from complex food samples.

Preparation of hyperbranched polyglycerol groups modified by sulfonic acid tags supported on magnetized kappa-carrageenan: A sustainable solid acid for the synthesis of 1-amidoalkyl-2-naphthols

In this study, the magnetization of kappa-carrageenan (Carr) and its modification by hyperbranched polyglycerol-sulfonic acid tags (PGly-SO3H) was found to be a good strategy to fabricate a bio-inspired solid acid as a heterogeneous nanocatalyst for the synthesis of 1-amidoalkyl-2-naphthols from aldehydes, 2-naphthol, and acetamide. The catalyst was produced by embedding Fe3O4 nanoparticles into carrageenan shell and modifying the as-produced Fe3O4@Carr with PGly tags. Then, the Fe3O4@Carr was modified by chlorosulfonic acid (Cl-SO3H) to obtain the Fe3O4@Carr-PGly-SO3H nanoparticles. The morphology and structure of Fe3O4@Carr-PGly-SO3H nanoparticles were studied by FT–IR, XRD, FE-SEM, EDX-mapping, TEM, VSM, and TGA. Aromatic aldehydes with electron-donor/ electron-acceptor substituents, heterocyclic aldehydes, and enolizable aldehyde gave the corresponding 1-amidoalkyl-2-naphthols with 85–96 % isolated yields within 15–35 min, under solvent-free conditions. The acidic content of Fe3O4@Carr-pPGly-SO3H nanoparticles was found to be 3.5 mmol H+/g, which determined by titration. As shown by TEM images, the Fe3O4 core facilitates the efficient magnetic separation. The use of a benign support material, ease of catalyst preparation and recovery, heterogeneous nature (on the basis of hot-filtration experiment), solvent-free conditions, and reusability of the nanoparticles (5 times) are some of the green aspects of the present study.

A light-driving magnetic nanocomposite based on Zn/Fe/Cu embedded in HKUST-1 applied for adsorption/degradation of Indigo carmine and pathogens

An environmentally friendly photocatalytic system (type-II heterojunction) is designed and utilized for rapid removal of Indigo carmine (IC) and pathogens from aqueous samples. This photocatalyst contains ZnFe2O4 magnetic NPs, CuO semiconductor, β-cyclodextrin (β-CD) charge transferor, and HKUST-1 light harvester. After the adsorption and photodegradation process, the nanocomposite was separated magnetically, and the supernatant was taken for the UV-Vis analysis. The maximum adsorption and photodegradation efficiency of 94.45% and 97.67% (pH = 5, in 35 min) were obtained under blue LED light (7.0 W) irradiation, due to the calculations based on UV-Vis spectrophotometer results. Simple preparation via a self-assembly route and facile separation through a superparamagnetic behavior (leading to great recovery) can be mentioned as the most brilliant excellence. Moreover, the photocatalytic performance of this magnetic nanocomposite was preserved after five recycle runs without any substantial reduction in photocatalytic activity. Also, employing a biopolymer, affordability, availability of the raw materials, good thermal stability, facile magnetic separation, simple operation, and high efficiency are upsides of the prepared nanocomposite, making it a superior photocatalyst to previous analogous systems. This nanocomposite (formulated as ZnFe2O4-CuO@β-CD)/HKUST-1) also exhibited antibacterial activity against Gram-positive and -negative strains. Based on BET (porosity) evaluations, the nanocomposite has rendered a surface area of 451.52 m2/g, which led to great adsorption results representing first-order and pseudo-second-order (Freundlich isotherm) kinetic models for the degradation and adsorption processes, respectively.

Regeneration possibilities and application of magnetically modified biochar for heavy metals elimination in real conditions

Although new types of composites with magnetic properties and high adsorption capacity for potentially toxic elements elimination are studied by researcherers, the information about the reusability, stability and removal efficiency of composites is still scarce or absent. Therefore, the aim of our work was applicate the sorbent to eliminate Zn(II), Cd(II) and Pb(II) ions from industrial waste leachates, and moreover, study the composite reusability and magnetic separation efficiency. Magnetically modified biochar was prepared from the fermentation residue of maise hybrid by a simple two-step method with microwave assistance. Composite properties, as well as the adsorption efficiency and magnetic response are depend on the extraction agent. The alkaline extraction agent showed the best properties for reusability and had no influence on Fe releasing from the composite, the adsorption efficiency was higher than 90% even in the 5th recycling cycle, and the composite remained magnetically active. The separation efficiency of composite from an aqueous environment by a magnet was higher than 95% within 15 min. Magnetically modified biochar proved to be an effective sorbent for metal ions elimination from wastewater.

Efficient removal of phosphate from aqueous media using magnetic bimetallic lanthanum‑iron-modified sulfonylmethylated lignin biochar

The use of lignin carbon as an adsorbent for the adsorption of phosphates from wastewater is a promising technology. However, most lignin carbon-based adsorbents still suffer from low adsorption efficiency and poor selectivity. Herein, a novel FeLaO3-modified sulfomethylated lignin (SL) biochar adsorbent (FLO@CSL) was prepared for phosphate removal. The development of this adsorbent took into consideration the strong affinity of lanthanum (La) and iron (Fe) (hydro) oxides for phosphate and the excellent carrier properties of lignin-based biochar. As the core of FLO@CSL, FeLaO3 active sites are highly dispersed on the surface of SL biochar. Besides, doping of Fe(III) not only imparts magnetic properties to FLO@CSL, thereby effectively improving the separation efficiency of the adsorbent, but also enhances the phosphate adsorption performance. Performance studies revealed that FLO@CSL exhibits remarkable adsorption selectivity and substantial phosphate-adsorption capacity. Notably, the maximum adsorption capacity was found to be 137.14 mg P g−1. Phosphate adsorption on the FLO@CSL surfaces proceeds via chemisorption in a single layer, and ligand exchange plays an important role in determining the adsorption behaviour. Because of its exceptional selectivity, remarkable adsorption capacity and outstanding magnetic separation efficiency, FLO@CSL is a highly promising adsorbent material for effectively treating phosphates in wastewater.

Investigating the Performance and Stability of Fe3O4/Bi2MoO6/g-C3N4 Magnetic Photocatalysts for the Photodegradation of Sulfonamide Antibiotics under Visible Light Irradiation

In this study, an Fe3O4/Bi2MoO6/g-C3N4 magnetic composite photocatalyst was synthesized for the visible-light-driven photocatalytic degradation of sulfonamide antibiotics, specifically sulfamerazine (SM1). Characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), photoluminescence spectroscopy (PL), UV-vis diffuse reflectance spectra (UV-vis), and the use of a vibrating sample magnetometer (VSM), were employed to analyze the fabricated samples. The composite exhibited efficient visible-light absorption and charge separation, with optimal photocatalytic performance achieved at a pH value of 9.0. The study reveals the importance of solution pH in the degradation process and the potential applicability of the composite for efficient magnetic separation and recycling in photocatalytic processes. The Fe3O4/Bi2MoO6/g-C3N4 magnetic composite photocatalyst demonstrated exceptional stability and recyclability, maintaining a high degradation efficiency of over 87% after five consecutive cycles. An XRD analysis conducted after the cycling tests confirmed that the composite’s composition and chemical structure remained unchanged, further supporting its chemical stability. This investigation offers valuable insights into the photocatalytic degradation of sulfonamide antibiotics using magnetic composite photocatalysts and highlights the potential of the Fe3O4/Bi2MoO6/g-C3N4 composite for practical applications in environmental remediation.

High-efficiency removal of arsenic(III) from wastewater using combined copper ferrite@biochar and persulfate

Arsenic (As) is a potentially toxic element with variable valence states. Due to high toxicity and bioaccumulation, As can pose a severe threat to the quality of the ecology as well as human health. In this work, As(III) in water was effectively removed by biochar-supported copper ferrite magnetic composite with persulfate. The copper ferrite@biochar composite exhibited higher catalytic activity than copper ferrite and biochar. The removal of As(III) could reach 99.8% within 1 h under the conditions of initial As(III) concentration at 10 mg/L, initial pH at 2–6, and equilibrium pH at 10. The maximum adsorption capacity of As(III) by copper ferrite@biochar-persulfate was 88.9 mg/g, achieving superior performance than mostly reported the metal oxide adsorbents. By means of a variety of characterization techniques, it was found that ∙OH acted as the main free radical for removing As(III) in the copper ferrite@biochar-persulfate system and the major mechanisms were oxidation and complexation. As a natural fibre biomass waste-derived adsorbent, ferrite@biochar presented a high catalytic efficiency and easy magnetic separation for As(III) removal. This study highlights the great potential of copper ferrite@biochar-persulfate application in As(III) wastewater treatment.

Silica-magnetite nanoparticles: Synthesis, characterization and nucleic acid separation potential

Silica-coated magnetic nanoparticles can be utilized for the magnetic separation of nucleic acids, which is an important step in many clinical procedures. A series of silica-functionalized superparamagnetic iron oxide nanoparticles (SiO2@MNPs) was synthesized to efficiently separate nucleic acids for the sensitive detection of viral infections. Magnetite nanoparticles (MNPs) coated with different thicknesses of silica layer resulting from different ratios of tetraethylorthosilicate (TEOS) precursor to magnetite (TEOS/MNPs = 0.4, 1.0, 2.0, 3.0, 4.0, 5.0 ml/g) have been selected for characterization of their physico-chemical properties and biological activities. The SiO2@MNPs' morphology, size, magnetic and surface properties, cytotoxicity and nucleic acid binding propensity were determined to select the ones with the highest RNA separation potential. Our results showed that RNA-binding properties and magnetic separation efficiency are nanoparticle size-dependent. The highest binding and separation efficiencies were detected for the smaller SiO2@MNPs with TEOS/MNPs (v/w) ratios equal to 1.0 and 2.0. These nanoparticles are promising candidates for clinical application relevant to RNA viruses.

Magnetic Multipedal DNA Walking Nanomachine Driven by Catalytic Hairpin Assembly.

miRNAs in circulating blood have been regarded as promising biomarkers for the diagnosis of a series of diseases. Development of ultrasensitive, reliable, and convenient methods for miRNA assay is of great significance. Herein, we present a novel electrochemical sensing strategy. The assembly of DNA walker strands on membrane-coated nanomaterials, target-mediated recycling activation, and electrochemical signal enrichment are integrated. Multipedal DNA walking with magnetic cores and a catalytic hairpin assembly at the electrode lead to the increase of electrochemical response, which can be used to probe initial target miRNA. This DNA walking nanomachine shows enhanced signal amplification efficiency and facile magnetic separation steps. It enables rapid analysis of miRNA at the attomole level and performs satisfactorily in samples of human circulating blood. Given the powerful sensitivity, facile operation, and excellent specificity, this magnetic multipedal DNA walker provides a promising way to determine miRNA level for biomedical applications.

Efficient recovery of phosphate by Fe3O4/La-MOF: An insight of adsorption performance and mechanism from electrochemical properties

Phosphorus (P) is known as a valuable resource, and recycling it from wastewater can avoid environmental pollution and resource waste. Herein, a regenerable magnetic Fe3O4 and La-based metal–organic framework functional material (Fe3O4/La-MOF) was synthesized by solvent thermal method and its adsorption performances of phosphate were evaluated. The as-prepared magnetic Fe3O4/La-MOF exhibited magnetic separation efficiency of 97.9% and it could maintain the high adsorption capacity over a wide pH range from 3 to 10, as well as showed an excellent P adsorption selectivity in presence of Cl-, NO3–, HCO3–, CO32– and SO42-. The isotherm data were consistent with the Langmuir model, and the adsorption kinetic data conformed to the pseudo-second-order model, revealing that there was chemical adsorption between Fe3O4/La-MOF and phosphate. The electrochemical behavior of Fe3O4/La-MOF before and after phosphate adsorption showed that the band gap energy of LUMO (Lowest Unoccupied Molecular Orbital) and HOMO (Highest Occupied Molecular Orbital) of P adsorbed Fe3O4/La-MOF was lower than that of the material itself, which indicated the successful adsorption of phosphate on Fe3O4/La-MOF and the forming of a perfect hybrid structure. The characterization analysis of FT-IR and XPS illustrated that intra-sphere complex (LaOP) formed between Fe3O4/La-MOF and phosphate by ligand exchange, which might be the dominant mechanism, followed by electrostatic attraction and precipitation. This study highlighted the great promise of magnetic reusable Fe3O4/La-MOF composite for application in phosphate removal and recovery.

Fe-Si alloys production and alumina extraction from coal fly ash via the vacuum thermal reduction and alkaline leaching

The comprehensive utilization of coal fly ash (CFA) has attracted extensive attentions owing to increasing awareness of environmental protection and secondary resource recycling. In this paper, a vacuum thermal reduction followed by magnetic separation and alkaline leaching was employed to produce FeSi alloys and extract alumina from CFA. The effects of Fe/Si ratios on the reduction of silica-containing phases in CFA and the magnetic separation of FeSi alloys were investigated. The results show that the reduction of metakaolinite and quartz in CFA was strengthened by increasing the Fe/Si ratios from 1.0 to 2.0, which makes the mean particle size of FeSi alloys increased from 14.11 μm to 20.54 μm. The magnetic separation efficiency of FeSi alloys was mainly depended on the Fe/Si ratios. As the Fe/Si ratios increased from 1.0 to 1.4, the magnetic separation efficiency increased from 79.68% to 89.03%; however, it decreased to 82.90% as the Fe/Si ratios further increased to 2.0. Meanwhile, the alumina extraction from non-magnetic fraction using the alkaline leaching was also studied. It is proved that the leaching rate of alumina can reach 96.95% under the optimal conditions. Compared with the traditional routes, the proposed process shows a good prospect for environmentally friendly utilization of CFA.

Demulsification Performance and Mechanism of Tertiary Amine Polymer-Grafted Magnetic Nanoparticles in Surfactant-Free Oil-in-Water Emulsion.

Numerous cationic magnetic nanoparticles (MNPs) have previously been developed for demulsifying oil-in-water (O/W) emulsion, and results showed that the cationic MNPs could effectively flocculate and remove the negatively charged oil droplets via charge attraction; however, to the best of our knowledge, there are no research reports regarding the synergetic influence of both the positive charge density and interfacial activity of MNPs on the demulsification performance. In this study, three tertiary amine polymer-grafted MNPs, namely, poly(2-dimethylaminoethyl acrylate)-grafted MNPs (M-PDMAEA), poly(2-dimethylamino)ethyl methacrylate)-grafted MNPs (M-PDMAEMA), and poly(2-diethylaminoethyl methacrylate)-grafted MNPs (M-PDEAEMA), were synthesized and evaluated for their demulsification performance. Results demonstrated that a high positive charge density and superior interfacial activity of MNPs could cause partial oil droplet re-dispersion when excessive MNPs were introduced, leading to a lower magnetic separation efficiency and narrower demulsification window. Herein, a demulsification window is defined as a range of nanoparticle dosages in which the MNPs can effectively demulsify the O/W emulsion under certain conditions. For highly positively charged MNPs, their good interfacial activity could aggravate the formation of a narrower demulsification window. When tertiary amine polymer-grafted MNPs carried a lower positive charge density or weak interfacial activity, that is, M-PDMAEA at pH 4.0, M-PDMAEMA at pH 5.0-9.0, and M-PDEAEMA at pH 9.0-10.0, wide demulsification windows were observed. Additionally, a recycling experiment suggested that MNPs could maintain high demulsification efficiency up to at least five cycles, indicating their satisfactory recyclability. The three tertiary amine polymer-grafted MNPs can be potentially used for efficient demulsification from surfactant-free O/W emulsion in various pH ranges.

Adsorptive removal of aflatoxin B1 from contaminated peanut oil via magnetic porous biochar from soybean dreg

The contamination of mycotoxin in edible oil has always been a major threat to human health. In this study, magnetic soybean dreg-based biochar SDB-6-K-9@Fe3O4 was prepared via co-precipitation and used to remove aflatoxin B1 (AFB1) from contaminated oil. The adsorbent characterization results revealed that the Fe3O4 was successfully loaded to the SDB-6-K-9. The 0.45SDB-6-K-9@Fe3O4 had paramagnetic properties with a saturation magnetization of 45.15 emu/g, which could be quickly separated from the peanut oil using an external magnet. The maximum adsorption capacity of peanut oil contaminated with 200 ng/mL AFB1 by 50 mg 0.45SDB-6-K-9@Fe3O4 for 2 h reached 0.1354 mg/g, while the removal process minimally affected the quality of the oil. The adsorption behavior results followed a pseudo-second-order kinetic and fitted well with the Freundlich model. The excellent adsorption removal efficiency and facile magnetic separation of the adsorbents provide a simple and efficient method for removing contaminants from the oil.

High-stable perovskite nanocrystal fluorescent probe-based aptasensor for ultrasensitive detection of peanut allergen Ara h1

Food allergy is a serious immune allergy reaction, that has attracted public attention all over the world due to the increasing incidence. Ara h1, the most abundant allergenic protein in peanuts, has been identified as a biomarker of peanut allergen. Therefore, a sensitive, efficient method for Ara h1 detection is urgently needed to protect allergy sufferers. In this study, a simple and efficient fluorescent aptasensor was proposed for ultrasensitive and rapid detection of peanut allergen Ara h1. The aptamer against Ara h1 was conjugated onto the surface of high-stable perovskite nanocrystal (PNCs) to serve as the fluorescence-labeled recognition probe as well as the signal probe, while the magnetic nanoparticles Fe3O4 (MNPs) were functionalized with the aptamer complementary DNA (cDNA) as the separation probe. The high-stable PNCs-labeled aptasensor Apt-PNCs@cDNA-MNPs gives the combined merits of the extraordinary optical properties of PNCs, the efficient magnetic separation capability of MNPs as well as the high specificity of aptamers. The developed high-stable PNCs-labeled aptasensor exhibited excellent linearity (0.1–100 ng/mL), and low limit of detection (0.04 ng/mL). The aptasensor was successfully applied for the determination of Ara h1 in food samples, implying great potential in the field of allergen assay.