Eco-friendly strategy for preparation of high-purity silica from high-silica IOTs using S-HGMS coupling with ultrasound-assisted fluorine-free acid leaching technology.

Iron ore tailings (IOTs), a typical hazardous solid waste, seriously threaten human health and the ecological environment. However, the abundance of quartz, particularly in high-silica IOTs, renders them useful. Yet, state-of-the-art technologies have rarely reported the preparation of high-purity silica from high-silicon IOTs. Thus, this study proposed an eco-friendly technology for producing high-purity silica from high-silica IOTs through the coupling of superconducting high gradient magnetic separation (S-HGMS) preconcentration with leaching followed by the use of ultrasound-assisted fluorine-free acid solution. Following an analysis of the separation index and chemical composition, the optimum conditions for the quartz preconcentration were determined as a magnetic flow ratio of 0.068 T s/m, a slurry flow velocity of 500 mL/min, and a pulp concentration of 40 g/L. Consequently, the SiO2 grade increased from 69.32% in the raw sample to 93.12% in quartz concentrate following the application of S-HGMS, with the recovery reaching 45.24%. X-ray diffraction, vibrating sample magnetometer, and scanning electron microscope analyses indicated that quartz was effectively preconcentrated from the tailings by S-HGMS. Subsequently, employing the "ultrasound-assisted fluorine-free acid leaching process," impurity elements were removed and high-purity silica was produced. Under optimal leaching conditions, the SiO2 purity of silica sand increased to 97.42%. Following a three-stage acid leaching process with 4 mol/LHCl +2 mol/LH2C2O4, the removal efficiency of Al, Ca, Fe, and Mg exceeded 97% for all cases, and the SiO2 purity in high-purity silica reached 99.93%. Thus, this study proposes a new strategy for the preparation of high-purity quartz from IOTs, which facilitated the effective realization of the high-value utility of the tailings. Furthermore, it provides a theoretical basis for the industrial application of IOTs, which is of great scientific significance and practical application value.

Agglomeration behaviour of magnetic microparticles during separation and recycling processes in mRNA purification.

Purification of mRNA with oligo(dT)-functionalized magnetic particles involves a series of magnetic separations for buffer exchange and washing. Magnetic particles interact and agglomerate with each other when a magnetic field is applied, which can result in a decreased total surface area and thus a decreased yield of mRNA. In addition, agglomeration may also be caused by mRNA loading on the magnetic particles. Therefore, it is of interest how the individual steps of magnetic separation and subsequent redispersion in the buffers used affect the particle size distribution. The lysis/binding buffer is the most important buffer for the separation of mRNA from the multicomponent suspension of cell lysate. Therefore, monodisperse magnetic particles loaded with mRNA were dispersed in the lysis/binding buffer and in the reference system deionized water, and the particle size distributions were measured. A concentration-dependent agglomeration tendency was observed in deionized water. In contrast, no significant agglomeration was detected in the lysis/binding buffer. With regard to magnetic particle recycling, the influence of different storage and drying processes on particle size distribution was investigated. Agglomeration occurred in all process alternatives. For de-agglomeration, ultrasonic treatment was examined. It represents a suitable method for reproducible restoration of the original particle size distribution.

Development of a 3D-printed single-use separation chamber for use in mRNA-based vaccine production with magnetic microparticles.

Laboratory protocols using magnetic beads have gained importance in the purification of mRNA for vaccines. Here, the produced mRNA hybridizes specifically to oligo(dT)-functionalized magnetic beads after cell lysis. The mRNA-loaded magnetic beads can be selectively separated using a magnet. Subsequently, impurities are removed by washing steps and the mRNA is eluted. Magnetic separation is utilized in each step, using different buffers such as the lysis/binding buffer. To reduce the time required for purification of larger amounts of mRNA vaccine for clinical trials, high-gradient magnetic separation (HGMS) is suitable. Thereby, magnetic beads are selectively retained in a flow-through separation chamber. To meet the requirements of biopharmaceutical production, a disposable HGMS separation chamber with a certified material (United States Pharmacopeia Class VI) was developed which can be manufactured using 3D printing. Due to the special design, the filter matrix itself is not in contact with the product. The separation chamber was tested with suspensions of oligo(dT)-functionalized Dynabeads MyOne loaded with synthetic mRNA. At a concentration of cB = 1.6-2.1 g·L-1 in lysis/binding buffer, these 1 µm magnetic particles are retained to more than 99.39% at volumetric flows of up to 150 mL·min-1 with the developed SU-HGMS separation chamber. When using the separation chamber with volumetric flow rates below 50 mL·min-1, the retained particle mass is even more than 99.99%.

Recovery of Metals from Heat-Treated Printed Circuit Boards via an Enhanced Gravity Concentrator and High-Gradient Magnetic Separator.

The recovery and reuse of waste printed circuit boards (PCBs) has attracted more and more attention from global researchers, as recycling of waste PCB metals is of great significance to the rational utilization of metal material resources. This study puts forward a clean and economical method in which enhanced gravity separation and wet high-gradient magnetic separation were combined to recover waste PCBs with heat treatment at a temperature of 240 °C. The heat treatment could improve the metal liberation effect of the PCBs, and the thermal behavior was measured by thermogravimetric analysis (TGA). The pyrolysis of the non-metal fraction (NMF) began around 300 °C, and the glass transition temperature of epoxy resin was 135.17 °C. The enhanced gravity separation technique was used for the separation of metals and NMF under the compound force field. The metals grade of the gravity concentrates fraction (GRF) was 82.97% under the optimal conditions, and the metals recovery reached 90.55%. A wet high-gradient magnetic separator was applied to classify the GRF into magnetic (MA) and non-magnetic (NMA) fractions, which could achieve iron and copper enrichment. After the three stages combined process, the copper and iron grades of the NMA and MA fractions were 70.17% and 73.42%, and the recovery reached 74.02% and 78.11%, respectively.

Low-Resource Nucleic Acid Extraction Method Enabled by High-Gradient Magnetic Separation.

Nucleic acid-based diagnostic tests often require isolation and concentration of nucleic acids from biological samples. Commercial purification kits are difficult to use in low-resource settings because of their cost and insufficient laboratory infrastructure. Several recent approaches based on the use of magnetic beads offer a potential solution but remain limited to small volume samples. We have developed a simple and low-cost nucleic acid extraction method suitable for isolation and concentration of nucleic acids from small or large sample volumes. The method uses magnetic beads, a transfer pipette, steel wool, and an external magnet to implement high-gradient magnetic separation (HGMS) to retain nucleic acid-magnetic bead complexes within the device's steel wool matrix for subsequent processing steps. We demonstrate the method's utility by extracting tuberculosis DNA from both sputum and urine, two typical large volume sample matrices (5-200 mL), using guanidine-based extraction chemistry. Our HGMS-enabled extraction method is statistically indistinguishable from commercial extraction kits when detecting a spiked 123-base DNA sequence. For our HGMS-enabled extraction method, we obtained extraction efficiencies for sputum and urine of approximately 10 and 90%, whereas commercial kits obtained 10-17 and 70-96%, respectively. We also used this method previously in a blinded sample preparation comparison study published by Beall et al., 2019. Our manual extraction method is insensitive to high flow rates and sample viscosity, with capture of ∼100% for flow rates up to 45 mL/min and viscosities up to 55 cP, possibly making it suitable for a wide variety of sample volumes and types and point-of-care users. This HGMS-enabled extraction method provides a robust instrument-free method for magnetic bead-based nucleic acid extraction, potentially suitable for field implementation of nucleic acid testing.

First comprehensive view on a magnetic separation based protein purification processes: From process development to cleaning validation of a GMP-ready magnetic separator.

Magnetic separation processes are known as integrated bioanalytical protein purification method since decades and are well described. However, use of magnetic separation processes in a regulated industrial production environment has been prevented by the lack of suitable process equipment and prejudice against the productivity of the process and its qualification for cleaning-in-place operation. With the aim of overcoming this prejudice, a comprehensive process development approach is presented, based on a GMP-compliant magnetic separator, including an optimization of the batch adsorption process, implementation into a technical-scale, and the development and validation of cleaning routines for the device. By the implementation of a two-step counter-current binding process, it was possible to raise the yields of the magnetic separation process even for very low concentrated targets in a vast surplus of competing proteins, like the hormone equine chorionic gonadotropin in serum, from 74% to over 95%. For the validation of the cleaning process, a direct surface swabbing method combined with a total organic carbon analysis was established for the determination of two model contaminants. The cleanability of the process equipment was proven for both model contaminants by reliably meeting the 10 ppm criteria.

Recovery of LaPO4:Ce,Tb from waste phosphors using high-gradient magnetic separation.

LaPO4:Ce,Tb (LAP) containing high terbium concentration was successfully recovered from waste phosphor from end-of-life fluorescent lamps by high-gradient magnetic separation (HGMS). In addition to HGMS, some contaminants in the waste phosphor, e.g., iron oxide and glass powder, were also removed by sieving and sedimentation. Repeating the magnetic separation procedure three times yielded LAP with a purity of 87%. Luminescence spectra intensities of recovered LAP were as high as 95% compared with virgin LAP. This recovery method will be useful during rare-earth crises.

One-step integrated clarification and purification of a monoclonal antibody using Protein A Mag Sepharose beads and a cGMP-compliant high-gradient magnetic separator.

Monoclonal antibodies are a dominant component of today's biopharmaceutical market and are typically purified by classical platform processes. However, high costs and rising demands are drivers for the development of new, efficient and flexible integrated purification processes. Currently, high-gradient magnetic separation as a direct capturing tool for protein purification suffers from the lack of suitable GMP-compliant separation equipment for industrial scale. As a solution for this bottleneck, we present a purification process for a monoclonal antibody directly from CHO cell culture by use of protein A-functionalized magnetic particles together with the first pilot-scale GMP-compliant 'rotor-stator' high-gradient magnetic separator. Five consecutive purification cycles were performed, achieving consistent yields of over 85% and purities of over 95%. Stable cell viabilities during the magnetic separation process enable integration of the device as an in situ product removal tool. A comparison with state-of-the-art protein A column-based purification processes reveals a 3-times higher process productivity per mL of applied resin and demonstrates the great potential of magnetic separation in downstream processing.

Magnetic Separation on a New Level: Characterization and Performance Prediction of a cGMP Compliant "Rotor-Stator" High-Gradient Magnetic Separator.

The growing market of biopharmaceuticals and the constant developments in upstream fermentation have generated a strong demand for new downstream purification methods. Magnetic separation in combination with functional magnetic particles has been known for many years as a promising candidate for a direct capturing tool in protein purification but the lack of suitable GMP-compliant purification equipment has prevented the launch of this technology in large scale bioprocessing. To tackle this bottle-neck, the principle of a "rotor-stator" high-gradient magnetic separator is fully redesigned to meet the rigorous requirements of modern cGMP biotechnology purification processes. In order to fulfill regulatory requirements, the separation chamber is reengineered to allow effective cleaning and sterilization in place while maintaining excellent separation capacities and efficiencies. Two kinds of commercially available magnetic particles are used to validate key performance data and determine system related parameters in order to calculate process performance figures for process optimization of the new magnetic separation device. With separation capacities of over 400 g of magnetic particles per liter of separation chamber volume and separation efficiencies as well as recovery rates over 99%, the system is able to process more than 200 l crude feedstock per day and capture more than 1.6 kg target compounds.

Adsorption combined with superconducting high gradient magnetic separation technique used for removal of arsenic and antimony.

Manganese iron oxide (MnFe2O4), an excellent arsenic(As)/antimony(Sb) removal adsorbent, is greatly restricted for the solid-liquid separation. Through the application of superconducting high gradient magnetic separation (HGMS) technique, we herein constructed a facility for the in situ solid-liquid separation of micro-sized MnFe2O4 adsorbent in As/Sb removal process. To the relative low initial concentration 50.0µgL-1, MnFe2O4 material sorbent can still decrease As or Sb below US EPA's drinking water standard limit. The separation of MnFe2O4 was mainly relied on the flow rate and the amount of steel wools in the HGMS system. At a flow rate 1Lmin-1 and 5% steel wools filling rate, the removal efficacies of As and Sb in natural water with the system were achieved to be 94.6% and 76.8%, respectively. At the meantime, nearly 100% micro-sized MnFe2O4 solid in the continuous field was readily to be separated via HGMS system. In a combination with the experiment results and finite element simulation, the separation was seemed to be independent on the magnetic field intensity, and the maximum separation capacities in various conditions were well predicted using the Thomas model (R2=0.87-0.99).

A sensitive biosensor using double-layer capillary based immunomagnetic separation and invertase-nanocluster based signal amplification for rapid detection of foodborne pathogen.

Combining double-layer capillary based high gradient immunomagnetic separation, invertase-nanocluster based signal amplification and glucose meter based signal detection, a novel biosensor was developed for sensitive and rapid detection of E. coli O157:H7 in this study. The streptavidin modified magnetic nanobeads (MNBs) were conjugated with the biotinylated polyclonal antibodies against E. coli O157:H7 to form the immune MNBs, which were captured by the high gradient magnetic field in the double-layer capillary to specifically separate and efficiently concentrate the target bacteria. Calcium chloride was used with the monoclonal antibodies against E. coli O157:H7 and the invertase to form the immune invertase-nanoclusters (INCs), which were used to react with the target bacteria to form the MNB-bacteria-INC complexes in the capillary. The sucrose was then injected into the capillary and catalyzed by the invertase on the complexes into the glucose, which was detected using the glucose meter to obtain the concentration of the glucose for final determination of the E. coli O157:H7 cells in the sample. A linear relationship between the readout of the glucose meter and the concentration of the E. coli O157:H7 cells (from 102 to 107 CFU/mL) was found and the lower detection limit of this biosensor was 79 CFU/mL. This biosensor might be extended for the detection of other foodborne pathogens by changing the antibodies and has shown the potential for the detection of foodborne pathogens in a large volume of sample to further increase the sensitivity.

Working principle and application of magnetic separation for biomedical diagnostic at high- and low-field gradients.

Magnetic separation is a versatile technique used in sample preparation for diagnostic purpose. For such application, an external magnetic field is applied to drive the separation of target entity (e.g. bacteria, viruses, parasites and cancer cells) from a complex raw sample in order to ease the subsequent task(s) for disease diagnosis. This separation process not only can be achieved via the utilization of high magnetic field gradient, but also, in most cases, low magnetic field gradient with magnitude less than 100 T m-1 is equally feasible. It is the aim of this review paper to summarize the usage of both high gradient magnetic separation and low gradient magnetic separation (LGMS) techniques in this area of research. It is noteworthy that effectiveness of the magnetic separation process not only determines the outcome of a diagnosis but also directly influences its accuracy as well as sensing time involved. Therefore, understanding the factors that simultaneously influence the efficiency of both magnetic separation process and target detection is necessary. Moreover, for LGMS, there are several important considerations that should be taken into account in order to ensure its successful implementation. Hence, this review paper aims to provide an overview to relate all this crucial information by linking the magnetic separation theory to biomedical diagnostic applications.

Effect and mechanism of a High Gradient Magnetic Separation (HGMS) and Ultraviolet (UV) composite process on the inactivation of microbes in ballast water.

The patented technology of a High Gradient Magnetic Separation (HGMS)-Ultraviolet (UV) composite process was used to treat ballast water. Staphylococcus aureus (S. aureus) was selected as the reference bacteria. After treatment by the HGMS-UV process, the concentration of S. aureus on the log 10 scale was lower than 2 at different flow rates, S. aureus suffered the most serious damage, and K(+) leakage of the bacteria was 1.73mg/L higher than separate 60min UV irradiation (1.17mg/L) and HGMS (0.12mg/L) processes. These results demonstrated that the HGMS-UV composite process was an effective approach to treat ballast water. Further, the HGMS process had synergistic action on the subsequent UV irradiation process and accelerated cell membrane damage. Meanwhile, the results of superoxide dismutase (SOD) activities of bacteria and DNA band analyses indicated that the inactivation mechanisms were different for HGMS and UV irradiation.