Magnetic Resin Research Articles

Enhanced Photo–Fenton Removal Efficiency with Core-Shell Magnetic Resin Catalyst for Textile Dyeing Wastewater Treatment

Heterogeneous photo–Fenton reactions have been regarded as important technologies for the treatment of textile dyeing wastewaters. In this work, an efficient core-shell magnetic anion exchange resin (MAER) was prepared through in situ polymerization and used to remove reactive brilliant red (X-3B) in a UV–Fenton system. The MAER exhibited satisfactory removal efficiency for X-3B because of its highly effective catalytic activity. More than 99% of the X-3B (50 mg/L) was removed within 20 min in the UV–Fenton reaction. This is because the uniformly dispersed core-shell magnetic microsphere resin could suppress the aggregation of Fe3O4 nanoparticles and, thus, enhance the exposure of Fe reaction sites for catalytic reaction with H2O2. The good adsorption capacity of MAER also played an important role in promoting contact between X-3B and reactive radicals during the reaction. Mechanism research showed that hydroxyl radical (•OH) was the main reactive radicals for the removal of X-3B in the MAER UV–Fenton system. The MAER can be easily separated by a magnet after catalytic reactions. Moreover, the matrix effects of different substrates (Cl−, NO3−, SO42−, and humic acid) were investigated. The results showed that SO42− could be beneficial to improve the removal of X-3B but that the others decrease the removal. The MAER UV–Fenton also removed significant amounts of total organic carbon (TOC) for the X-3B solution and an actual textile dyeing industrial wastewater. The heterogeneous oxidation system established in this work may suggest prospects for practical applications in the treatment of textile dyeing wastewater.

Core–Shell Magnetic Micropillars for Reprogrammable Actuation

Stimuli-responsive micro/nanostructures that exhibit not only programmable but also reprogrammable actuation behaviors are highly desirable for various advanced engineering applications (e.g., anticounterfeiting, information encoding, dynamic imaging and display, microrobotics, etc.) but yet to be realized with state-of-the-art technologies. Here we report a concept and a corresponding experimental technique for core-shell magnetic micropillars enabling simultaneously programmable and reprogrammable actuations using a simple magnetic field. The micropillars are composed of elastomeric hollow shells for shaping encapsulated with liquid magnetic nanocomposite resin cores for actuating. The spatial distribution of the magnetic nanoparticles inside the resin channels can be dynamically modulated within individual micropillars, which consequently regulates the magnetomechanical responses of the pillars upon actuation (bending deformation varied near 1 order of magnitude under the same actuation field). We demonstrate that the micropillars with contrasting bending responses can be configured in an arbitrary spatial pattern by direct magnetic writing, and the written pattern can then be easily magnetically erased to facilitate next-round rewriting and reconfiguration. This reprogrammable actuation capability of the micropillars is further demonstrated by their potential applications for rewritable paper and recyclable displays, where various microscale characteristics can be controlled to dynamically appear and disappear at the same or different locations of one single micropillar array. The core-shell magnetic micropillars reported here provide a universal prototype for reprogrammable responsive micro/nanostructures through rational design and facile fabrication from conventional materials.

Titanate coupling agent surface modification effect on the magnetic properties of iron-based alloy powder coil prepared using screen printing

A molded-type coil is prepared by filling and dry pressing granulated alloy magnetic powders directly onto enameled wire. As the molded-type coil is developed toward miniaturization, the granules consisting of magnetic powder and organic binder cannot uniformly fill the small space in the coil center column during molding. This leads to a porous microstructure or cracks. In this study, magnetic alloy powder coils were prepared using a screen-printing process using high-solid-content magnetic pastes. The magnetic powder was surface-modified with titanate coupling agent to improve the magnetic powder and epoxy resin compatibility, thereby improving magnetic powder mixing with epoxy resin and reducing the high solid content magnetic paste viscosity. The experimental results showed that the relative density and magnetic properties (such initial permeability, core loss, and coercivity) can be significantly enhanced using titanate coupling agent surface modification.

Quantitative nascent proteome profiling by dual-pulse labelling with O-propargyl-puromycin and stable isotope-labelled amino acids.

Monitoring translational regulation in response to environmental signals is crucial for understanding cellular proteostasis. However, only limited approaches are currently available for quantifying acute changes in protein synthesis induced by stimuli. Recently, a clickable puromycin analogue, O-propargyl-puromycin (OPP), was developed and applied to label the C-termini of nascent polypeptide chains (NPCs). Following affinity purification via a click reaction, OPP allows for a proteomic analysis of NPCs. Despite its advantage, the affinity purification of NPCs using magnetic beads or resins inherently suffers from significant non-specific protein binding, which hinders accurate quantification of the nascent proteins. To address this issue, we employed dual-pulse labelling of NPCs with both OPP and stable isotope-labelled amino acids to distinguish bona fide NPCs from non-specific proteins, thereby enabling the accurate quantitative profiling of NPCs. We applied this method to dissecting translation responses upon transcriptional inhibition and quantified ∼3,000 nascent proteins. We found that the translation of a subset of ribosomal proteins (e.g. RPSA, RPLP0) as well as signalling proteins (e.g. BCAR3, EFNA1, DUSP1) was significantly repressed by transcription inhibition. Together, the present method provides an accurate and broadly applicable nascent proteome profiling for many biological applications at the level of translation.

Fabrication of magnetic polymeric resin for the removal of toxic metals from aqueous medium: Kinetics and adsorption mechanisms

Discharge of heavy metals without proper treatment of the industrial wastewater and resulted damages to the aquatic ecosystems and human health. In the present study, a magnetic adsorbent containing carboxylic acid and amino functional groups was fabricated using ethylenediaminediacetic (EDDA) acid, glutaraldehyde and CuFe2O4 nanoparticles. The structure and composition of the fabricated nanocomposite (EG@ CuFe2O4) was analyzed by FTIR, TGA, XRD, BET, SEM, TEM, XPS etc, and employ for the removal of Hg(II) and Pb(II) from aqueous medium. The adsorption kinetics and adsorption isotherm model was used for further characterization of the adsorption process for the metal ions, and support the pseudo- second order kinetics and Langmuir model. The thermodynamic parameters (ΔGo < 0, ΔHo > 0) support, spontaneous and endothermic adsorption. All these results revealed that the as fabricated magnetic EG@ CuFe2O4 nanocomposite can be used as an eco-friendly, proficient and cheap adsorbent for the adsorption of heavy metals form aqueous solution.

Synthesis of triethylene tetramine-modified water-insoluble corn flour caged in magnetic chitosan resin and its adsorption application for removal of patulin from apple juice.

In this study, triethylene tetramine-modified water-insoluble corn flour caged in magnetic chitosan resin (TETA-WICF/MCR) was firstly prepared, which indicates novel aspects for immobilization and chemically modification of mycotoxin adsorbents. The TETA-WICF/MCR was characterized using zoom stereo microscope, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometer (XRD), and magnetic separation performance analysis. Experimental results confirmed successful layer by layer modification of chitosan, biosorbent water-insoluble corn flour (WICF), TETA onto the surface of magnetic beads. The mean diameter of the TETA-WICF/MCR was 2.63mm with good magnetic-responsive ability. Subsequently, the adsorption performance of the TETA-WICF/MCR obtained toward patulin was assessed in batch adsorption system and the results demonstrated that the adsorption process was strongly depended on adsorbent dosage, contact time, temperature, and initial patulin concentration. The results of SEM images and FTIR analysis showed obvious changes in the porous structure of TETA-WICF/MCR after adsorbing patulin, and -NH2 and -OH groups were predominantly involved in the adsorption of patulin. Furthermore, the adsorption kinetics followed the mechanism of pseudo-second-order model, and equilibrium data were well fitted in the Freundlich isotherm model. It was also found that the TETA-WICF/MCR had good reusability without any adverse changes in apple juice. PRACTICAL APPLICATION: Patulin is a regulated toxin biosynthesized by certain fungi that contaminate agricultural commodities, such as fruits, juices, and other beverages. Several approaches have been studied to reduce patulin levels in apple juice and other aqueous systems. There is need for more low-cost and eco-friendly adsorbent capable of detoxifying patulin contaminated. In this sense, triethylene tetramine-modified water-insoluble corn flour caged in magnetic chitosan resin (TETA-WICF/MCR) was first prepared and exhibits easy solid-liquid separation and high adsorption capacity for removing patulin from contaminated apple juice.

The effect of incorporating inorganic materials into quaternized polyacrylic polymer on its mechanical strength and adsorption behaviour for ibuprofen removal

Quaternized polyacrylic polymer has many applications in water treatment because of its ion exchange effects, but its further industrial applications are largely restricted because of its poor mechanical strength. In this work, a magnetic anion exchange resin with a polyacrylic matrix (MAP) was prepared by incorporation of Fe3O4 and subsequent modification with tetraethyl orthosilicate (TEOS) to improve the mechanical strength and adsorption performance. The incorporation of Fe3O4 significantly enhanced the mechanical strength of the polymer and improved the sphericity rate after ball milling of the polyacrylic resin from 80.1% to 97.2% as a result of hydrogen bonding between the -OH groups on Fe3O4 and the -NH- groups on the resin matrix. Further TEOS modification could effectively prevent Fe3O4 particles from dislodging from the resins. The adsorption performance was evaluated by using ibuprofen as a model compound. The adsorption kinetics showed that adsorption equilibrium was reached in 150 min. XPS analysis indicated that hydrogen bonding greatly contributed to the adsorption of ibuprofen onto the MAP. Adsorption isotherm analysis indicated that the adsorption was endothermic.

Rapid 3D Printing Magnetically Active Microstructures with High Solid Loading

The cover image presents a 3D printed 9-mm-height magnetically-active structure featuring intricate 3D shapes and fine (sub-75-μm) features. The strong magnetic interaction allows it to be suspended against gravity using a small magnet on the top. It was accomplished via the synergy of the optimization of magnetic photopolymerizable resin and the high-speed 3D printing using micro-continuous liquid interface production (μCLIP) process. Further details can be found in the article, number 1900911 by Longqiu Li, Cheng Sun, and co-workers.

Development and Characterization of Stable Polymer Formulations for Manufacturing Magnetic Composites

Polymer bonded permanent magnets find significant applications in a multitude of electrical and electronic devices. In this study, magnetic particle-loaded epoxy resin formulations were developed for in-situ polymerization and material jetting based additive manufacturing processes. Fundamental material and process issues like particle settling at room temperature and elevated temperature curing, rheology control and geometric stability of the magnetic polymer during the thermal curing process are addressed. Control of particle settling, modifications in rheological behavior and geometric stability were accomplished using an additive that enabled the modification of the formulation behavior at different process conditions. The magnetic particle size and additive loading were found to influence the rheological properties significantly. The synergistic effect of the additive enabled the developing of composites with engineered magnetic filler loading. Morphological characterization using scanning electron microscopy revealed a homogenous particle distribution in composites. It was observed that the influence of temperature was profound on the coercive field and remanent magnetization of the magnetic composites. The characterization of magnetic polymers and composites using rheometry, scanning electron microscopy, X-ray diffraction and superconducting quantum interference device (SQUID) magnetometry analysis enabled the correlating of the behavior observed in different stages of the manufacturing processes. Furthermore, this fundamental research facilitates a pathway to construct robust materials and processes to develop magnetic composites with engineered properties.

Rapid 3D Printing Magnetically Active Microstructures with High Solid Loading

The capability of fabricating magnetically active 3D microstructures is crucial for miniaturization of microrobots or microactuators. While additive manufacturing using magnetic nanoparticle‐infused polymer resin offers the highly desirable precision and flexibility, the difficulty in handling resin with higher solid loading of magnetic nanoparticles needed to maximize the magnetic actuation forces remains to be the main obstacle. The increased viscosity of the magnetic resin not only significantly reduces the fabrication speed, but also makes the process vulnerable to the precipitation of the suspended magnetic nanoparticles. Herein, a comprehensive solution that synergizes the optimization of magnetic photopolymerizable resin and the high‐speed 3D printing using microcontinuous liquid interface production (μCLIP) process is reported. An optimized magnetic photopolymerizable resin with 30 wt% solid loading of Fe3O4 nanoparticles is well dispersed over 72 h. Process characteristics of the magnetic photopolymerizable resins with variation in the solid loading of magnetic nanoparticles are investigated experimentally. The capability of 3D printing centimeter‐size samples with sub‐75 μm fine features using high solid loading (30 wt%) is also demonstrated. The increased printing speed using μCLIP significantly reduces the fabrication time to the order of minutes to hours, making the process more robust against the precipitation of the magnetic particles.

Efficient removal of acid dyes using permanent magnetic resin and its preliminary investigation for advanced treatment of dyeing effluents

Abstract In order to deal with the contamination of dyes in wastewater, a new kind of magnetic strongly basic anion-exchange resin (noted as CDD-1) was prepared and characterized in this study. Batch experiments were performed to investigate its adsorption behaviors of two acid dyes sunset yellow (FCF) and acid green (AG9) under different experimental conditions. The reusability and adsorption performance of CDD-1 resin for biologically treated dyeing effluents treatment were also evaluated. The maximum adsorption capacity of FCF and AG9 onto CDD-1 resin at 308 K were 1.85 and 1.44 mmol/g, respectively. When the initial concentrations of two dyes were 0.05, 0.25 and 0.50 mmol/L, the initial adsorption rates of FCF were 1.76, 4.09 and 7.37 times higher than that of AG9, respectively. The FCF appeared a homogeneous monolayer chemisorption, while the AG9 adsorption was more like a multilayer adsorption, indicating other interactions except ion exchange may occur during the AG9 adsorption. The CDD-1 resin could be reused with most of its virgin adsorption capacity (93.6% for FCF and 78.9% for AG9) after 10 successive adsorption-desorption cycles. For real dyeing effluents treatment by the CDD-1 resin, the removal efficiencies of color degree were more than 90%, while that of CODcr were about 35–60%, which rendered it great potential for advanced treatment of dyeing effluents.

Study on the adsorption and desorption performance of magnetic resin for Congo red

ABSTRACT This study was to evaluate the adsorption capability of a magnetic resin (NDMP) to the removal of Congo red (CR) from aqueous solution. The adsorption kinetic and isotherm of NDMP were studied, as well as the desorption performance of NDMP. The results showed that the adsorption process of NDMP on CR was more suitable for Pseudo-second-order kinetic model. The whole adsorption process was affected by intraparticle diffusion and ion exchange. The adsorption isotherm of CR by NDMP was fitted better with Langmuir model. It showed that the adsorption of CR on NDMP resin was single layer adsorption. The maximum adsorption capacity (Qm ) of CR at 308 K can reach 354.29 mg/g. In the desorption, 10% NaCl and NaOH eluents had better desorption rate for CR than other mass fraction. While NaCl(10%)-MeOH mixed eluent with volume ratio of 3:7 had the best regeneration performance. The desorption rate can reach 90% within 30 min. The adsorption performance of NDMP on CR didn't decrease after 13 times successive adsorption–desorption by NaCl(10%)-methanol eluent, indicating that NDMP can be efficiently regenerated. The excellent adsorption–desorption performance of NDMP on CR suggests that the magnetic resin has a great potential for treating CR dye wastewater.

Efficient co-removal of copper and tetracycline from aqueous solution by using permanent magnetic cation exchange resin

This work aimed to examine a permanent magnetic cation-exchange resin (MCER) for synergistic co-removal of Cu(II) and tetracycline (TC) from their mixed solutions. Batch adsorption experiments and characterizations were performed to elucidate the adsorption mechanisms. The adsorption of Cu(II) followed the Langmuir isotherm model in most cases, while Freundlich isotherm model was more suitable for fitting TC adsorption, which was due to the surface coordination between adsorbed Cu(II) and TC and the formation of multilayer MCER-Cu-TC complexes. The equilibrium TC adsorption amount in binary Cu/TC system was about 5.5–13.5 times of that in sole system, whereas Cu(II) uptake was nearly unchanged. Decomplexing-bridging was ascribed as the primary mechanism, which involved the [Cu-TC] decomplexing and [resin-Cu] bridging for TC uptake. Moreover, these MCER microbeads could be reused with negligible loss in adsorption capacity during five adsorption-desorption cycles, indicative of great potential in synergistic co-removal of organics-Cu complexes from aqueous solutions.

Preparation of magnetic resin microspheres M-P(MMA-DVB-GMA) and the adsorption property to heavy metal ions

Magnetic resin microspheres called MPMDG2 were prepared by suspension polymerization combined with basic and acidic hydrolysis. The adsorption property of resin microspheres to heavy metal ions was investigated. Structural and morphological analysis revealed that the resin had high specific surface area and mesoporous structure. The resin contained about 9.2 wt% Fe3O4 and exhibited a high magnetic response. Adsorption experiments showed that the resin can selectively absorb Cr(III) and Pb(II) ions. The adsorption process was well described by a pseudo-second-order kinetic model, and the equilibrium adsorption data fitted the Langmuir isotherm model better than the Freundlich model. Ion exchange along with chemistry chelating was the most probable mechanisms for the adsorption of metal ions on the resin. The superior magnetic response, regeneration and selective adsorption property of the MPMDG2 make it a good candidate as an adsorbent for removing Cr(III), Pb(II) and Cu(II) from wastewater.

Preparation of magnetic mesoporous epoxy resin by initiator-free ring-opening polymerization for extraction of bile acids from human serum

In this work, we reported a simple two-step method for the synthesis of magnetic mesoporous epoxy resin (MMER), including one-pot template-free hydrothermal synthesis of nanoscale amine-functionalized magnetic nanoparticles (MN-NH2) and initiator-free ring-opening polymerization of epoxy resin. The resultant MMER was characterized in detail by transmission electron microscope (TEM), Fourier transform-infrared (FT-IR) spectra, X-ray photoelectron spectroscopy (XPS), thermogravimetic analysis (TGA) and magnetization curves. These results demonstrated successful synthesis of MMER with sufficient magnetic property and excellent thermal stability. The epoxy resin was covalent bonding MN-NH2 on and synthesized by hydrophobic monomers, so the MMER exhibited excellent adsorption quantity for hydrophobic bile acids. The MMER was used as magnetic solid-phase extraction (MSPE) sorbent, and combined with liquid chromatography-tandem mass spectrometry to extract and monitor 11 kinds of bile acids from serum sample. The proposed MSPE combined with LC–MS/MS method exhibited low limit of detection between 0.1 and 5 ng mL−1. In blank serum sample, 9 kinds of bile acids were detected, and ranged from −2.29 ng mL−1 to 6.86 ng mL−1. In standard addition recovery test, the recovery values of detectable bile acids ranged 102.4% to 108.5%, 96.0% to 104.0% and 82.3% to 103.3% when spiked with 0.2, 2.0 and 20 ng mL−1, respectively. The intra- and inter-day precision (n = 6) ranged 3.7% to 5.9% and 7.0% to 9.5%, respectively. The above results demonstrated that the MSPE combined with LC–MS/MS method was accurate and effective for quantitative determination of bile acids from complex biological samples.

MagC, magnetic collection of ultrathin sections for volumetric correlative light and electron microscopy.

The non-destructive collection of ultrathin sections on silicon wafers for post-embedding staining and volumetric correlative light and electron microscopy traditionally requires exquisite manual skills and is tedious and unreliable. In MagC introduced here, sample blocks are augmented with a magnetic resin enabling the remote actuation and collection of hundreds of sections on wafer. MagC allowed the correlative visualization of neuroanatomical tracers within their ultrastructural volumetric electron microscopy context.

Synthesis and characterization of egg-albumen-formaldehyde based magnetic polymeric resin (MPR): Highly efficient adsorbent for Cd(II) ion removal from aqueous medium

In this study, egg-albumen-formaldehyde based magnetic polymeric resin (MPR) was synthesized and used for the removal of Cd(II) ion from aqueous solution. Different variables affecting the adsorption of Cd(II) ion such as sorption time, pH of the solution, initial concentration of Cd(II) ion and temperature were also examined. The percentage removal of Cd(II) ion was increased with increasing contact time and temperature. The highest removal of Cd(II) ion was observed at pH 7 and the equilibrium was achieved within 4 h. Thermodynamic factors such as ΔG°, ΔH° and ΔS° were also evaluated from graphical interpretation of the experimental results. Thermodynamic and kinetic analyses showed that the adsorption process was spontaneous and endothermic, which fitted well with the pseudo-first-order kinetic model and Langmuir isotherm model. The maximum adsorption capacity which was obtained using Langmuir equation was found to be 149.3 mg g−1 at 298 K which was increased with increasing temperature. Regeneration studies were also performed using 0.1 M HCl solution to examine the reusability characteristics of MPR. Consequently, it was concluded that the MPR could be successfully used for the removal of the Cd(II) ion from aqueous medium.

Efficient removal of Cu(II) and citrate complexes by combined permanent magnetic resin and its mechanistic insights

Owing to the enormous threat from anthropogenic contamination in water resources, the effective control of heavy-metal pollution has become increasingly important. In this study, the combination of permanent magnetic anion exchange resin (MAER) and magnetic cation exchange resin (MCER) was employed to efficient removal of Cu(II) and citrate acid (CA). The removal mechanisms were systematically investigated by batch adsorption experiments, and also certificated by species distribution calculation, kinetic tests and solid-phase characterizations. The presence of CA markedly inhibited the adsorption of Cu(II) onto MCER, while the co-existing Cu(II) was beneficial for CA uptake onto MAER. With the increase of Cu(II) concentrations, the adsorption amount of CA onto MAER gradually increased and reached a plateau, with promotion rates ranging of 24.4%–47.9%. For combined magnetic resins treatment, as the MAER dosage increased from 0 to 1.50 g/L, the removal efficiencies of CA and Cu(II) were enhanced from 1.1% and 33.2% to 98.8% and 99.1%, respectively. The anionic [Cu-CA] complexes (mainly CuL− and a small fraction of Cu2L22−) in bi-solutes system possessed higher affinity than free-CA species towards MAER, resulting in a mutual enhancement of Cu(II) and CA uptake. Both decomplexing-adsorption of Cu(II) from neutral Cu species (CuHL0) by MCER and direct complex-adsorption of anionic complex species (CuL− and Cu2L22−) by MAER were proposed as the mechanisms for synergetic removal of CA and Cu(II) in combined processes. Furthermore, nanoscale Cu powders were recovered from the desorption liquid by chemical reduction. The combined magnetic resins exhibited superior reusability over five repeated cycles, indicating their great potential in treatment of complexing heavy metal-organic acid wastewaters.

A novel magnetic mesoporous resorcinol–melamine–formaldehyde resin for removal of phenols from aqueous solution

Here, a novel resorcinol–melamine–formaldehyde based mesoporous magnetic resin (m-RMF) was prepared via simple steps. The m-RMF resin was characterized by Fourier Transfer Infrared, scanning electronic microscopy and vibrating sample magnetometer. The m-RMF possesses a specific surface area of 520 m2/g, a pore volume of 0.45 cm3/g and an average pore diameter of 8.6 nm. The adsorptive performance of the m-RMF was investigated for phenol and 4-chlorophenol removal from simulated aqueous solutions under varying conditions. The results showed that m-RMF exhibited better adsorption performance for the removal of phenol (2.49 mmol/g) than 4-chlorophenol (1.5 mmol/g). The adsorption data were represented by pseudo-second order and Langmuir isotherm equations. The removal mechanism was realized by synergistic proton donor–acceptor complex, π–π interactions and hydrophobic effects.

Integrated treatment of tailing material for the selective recovery of uranium, rare earth elements and heavy metals

Processed ores may contain substantial amounts of residual valuable metals. In the case of the mining wastes issued from the exploitation of gibbsite bearing shale ore in the Southwestern Sinai, the characterization of the residue shows the presence of uranium, rare-earth elements (REEs), aluminum and zinc that can be valorized. Pug leaching at 120 °C with an acid consumption of about 200 kg H2SO4 per ton of ore succeeded in leaching more than 94% of U(VI) and REEs (in addition to substantial amounts of Al(III) and Zn(II)). A series of selective precipitation steps allowed successively recovering (almost quantitatively) Zn(II), Fe(III) and Al(III). In a second step, a magnetic resin has been used for enriching the pregnant leaching solution (by a factor close to 19) through sorption/desorption steps. In the last stage of the process, REEs were recovered by selective precipitation using 25% (w/w) oxalate solution at pH 1.5, while uranium was fully recovered by precipitation with NaOH at pH 9. Energy dispersive X-ray analysis performed on the different precipitates showed purity grades systematically superior to 93%.