Removal Of Impurities Research Articles

Harnessing ceramic hydroxyapatite as an effective polishing strategy to remove product- and process-related impurities in bispecific antibody purification

Bispecific antibody (bsAb), a novel therapeutic modality, provides excellent treatment efficacy, yet poses numerous challenges to downstream process development, which are mainly due to the intricate diversity of bsAb structures and impurity profiles. Ceramic hydroxyapatite (CHT), a mixed-mode medium, allows proteins to interact with its calcium sites (C-sites) through metal affinity and/or its phosphate sites (P-sites) through cation exchange interactions. This dual-binding capability potentially offers unique bind and elute behaviours for different proteins of interest, resulting in optimal product purity when suitable elution conditions are employed. In this study, the effectiveness of CHT as a polishing step for bsAb purification was investigated across three model molecules and benchmarked against the traditional cation exchange chromatography (CEX). For both asymmetric and symmetric IgG-like bsAb post Protein A eluates, at least 97% product purity was achieved after CHT polishing. CHT delivered a superior aggregate clearance to CEX, resulting in low high molecular weight (HMW) impurities (0.5%) and low process-related impurities in the product pools. Moreover, CHT significantly mitigated "chromatography-induced aggregation" whereas eightfold more HMW was generated by CEX. This study illustrated the developability of CHT in effectively eliminating low molecular weight (LMW) impurities through post-load-wash (PLW) optimization, resulting in an additional reduction of up to 48% in LMW impurities. A mechanistic explanation regarding the performance of impurity removal and mitigation of the chromatography-induced aggregation by CHT was proposed, illustrating unique CHT capability is potentially driven by C-site cooperation, of which effectiveness could depend on the bsAb composition and size.Graphical abstract

Study on magnetic and structural properties of Fe65Co35 soft magnetic alloy prepared by arc melting and subsequent annealing

Fe65Co35 based soft magnetic alloys (SMAs) have been gaining attention for their superior magnetic features and playing significant roles in composite permanent magnets, magnetic storage and automotive electrification technologies. In the present work, the Fe65Co35 alloy were produced by arc melting with subsequent annealing. The effects of arc melting and annealing upon the structural and magnetic properties of the soft magnetic phase of the alloy Fe65Co35 have been investigated. The variation in magnetic and microstructural characteristics with melting and annealing have been observed using the X-ray diffractometer (XRD), scanning electron microscope (SEM), and the vibrating sample magnetometer (VSM). The XRD patterns verified the existence of the Fe65Co35 alloy. After melting and annealing, the alloy surface morphologies were examined using SEM. In this approach, the Fe65Co35 alloy was annealed at 600 °C for 4 h in an argon environment which resulted in the highest saturation magnetization of 237 emu/g and the lowest coercivity of 31 Oe. The rise in saturation magnetization was attributed to the removal of impurities, during the melting and annealing process.

Porous materials with suitable pore size and dual‐functional sites for benchmark one‐step ethylene purification

AbstractMultiple impurities removal represents one of the most daunting challenges in gas purification, but the attainment of efficient adsorptive separation is hindered by the difficulty in designing adsorbents that could simultaneously capture different impurities. Herein, we revealed a molecular trap within Zn‐trz‐ox (trz = 1,2,4‐triazole; ox = oxalic acid) that featured positive H and negative O sites, and the suitable pore size, which exhibited remarkable one‐step C2H4 purification performance directly from quaternary C2H4/C2H2/C2H6/CO2 mixtures. The separation selectivities of C2H4 with respect to CO2, C2H2, and C2H6 are 9.8, 2.6, and 2.5, higher than the sole adsorbent yet reported. Meanwhile, polymer grade C2H4 (≥99.95%) could be directly obtained with record C2H4 productivity of 1.5 mol kg−1, over 10 times higher than that of the previous benchmark material. The deep insight into the binding behavior revealed by simulation studies offers important clues for the design of advanced adsorbent for multiple impurities capture.

Ten-Year Recycling of Vanadium Alloy in Fusion Reactors

Low-activation characteristics and dominant radioactive isotopes limiting materials recycling were analyzed for a fusion-reactor-grade vanadium alloy, NIFS-HEAT-2. In order to reduce contact dose rate after use in fusion reactors, purification of the base metal vanadium was examined by chemical aqueous separation, electron-beam vacuum melting and zone refining, focusing on the removal of the dominant high-activation impurities, such as Co, Cu, Fe, Nb, Ni and Mo. Based on the measured impurity levels, remote recycling of vanadium alloy is possible within ten years after use in fusion reactors under operation condition with 100 dpa irradiation. Early quasi-hands-on recycling requires further purification and re-design of alloy composition especially with low Ti and high Cr content. The present paper discusses status of material R&Ds for the ten-year recycling and impact on operation of fusion reactors.

Preparation of natural antibacterial regenerated cellulose fiber from seed-type hemp

Seed-type hemp fiber is hard to spinning and weaving because of its high lignin and hemicellulose content. In this work, the impurities in seed-type hemp fiber were removed by alkali degumming method, ammonium oxalate-complex enzyme method, ethylenediamainetetraacetic acid disodium -complex enzyme method, ammonium oxalate-complex enzyme-chemical method and ethylenediamainetetraacetic acid disodium -complex enzyme-chemical method, and the results were compared. The fibers were characterized by scanning electron microscopy (SEM) and fourier-transform infrared spectroscopy (FTIR). The fiber after impurity removal is prepared into pulp, and the structure of pulp was characterized by fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The hemp pulp was dissolved into ZnCl2 aqueous solution at a specific temperature to prepare a spinning solution and spun to produce antimicrobial seed-type hemp regenerated cellulose fibers by using a self-made spinning machine. The surface morphology, strength, moisture regain, and antibacterial properties were evaluated, the regenerated fibers had a superior performance.

Evaluation of Uses of Some Enzymes in Removal of Plant Impurities from Raw Wool Fabrics

In this study, phytase from Bacillus megaterium EBD9-1 and cellulase from Bacillus subtilis 171ES obtained from isolated from different provinces soils, and commercial pectinase enzymes were investigated for the removal potential of plant impurities from raw wool fabrics. Enzymatic removal of plant impurities is usually carried out at pH 4.0. The efficiency of the enzyme was shown at pH 7.0, but the best effect was obtained with pH 4.0. Enzymes were effective alone, but the effects of double and triple enzyme mixtures on plant impurities were more. It was determined that the effect decreased in case the enzyme amount was used low, and the effect increased even more in the presence of the concentrated enzyme. With this study, which was carried out for the first time with local isolate, the operability of more environmentally friendly enzymes in carbonization processes traditionally performed with chemical substances was demonstrated.

Influence of Surface Waves on Liquid-to-Gas Mass Transfer in Molten Silicon

Abstract The paper focuses on the numerical analysis of the mass transfer of impurities from the wavy surface of molten silicon to the gas phase. The mathematical model is described herein, with the modelling of a wavy silicon melt surface being done with the moving mesh technique. The model employs assumptions about the mass transfer process on the surface, namely, that it can be modelled with effective diffusion across the interface. The assumption is verified against limited experimental data for a stationary melt surface, and reasonable agreement is obtained. Thereafter, numerical studies are undertaken for a wavy melt surface. The dependence of impurity removal rate on the wave amplitude, wavelength and frequency is analysed. It is shown that the waves on the surface of the liquid increase the mass transfer rate in a certain parameter range. Finally, results are analysed to find an explanation for this increase and to determine technological factors that impact it. Surface enlargement due to waves and altered flow patterns near the silicon melt are determined as potential reasons for the improved impurity removal rate. A dimensionless criterion for the minimal wave amplitude required to obtain improved impurity removal is found and discussed.

Electrochemical selective lithium extraction and regeneration of spent lithium iron phosphate

In this paper, a green, efficient and low-cost process for the selective recovery of lithium from spent LiFePO4 by anodic electrolysis is proposed. The leaching rates of Li, Fe and P under different conditions were explored and the optimal conditions are obtained. In the optimal conditions, Li, Fe and P leaching rates were 96.31%, 0.06% and 0.62% respectively. The Li/Fe selectivity was over 99.9%. The product obtained is isostructural FePO4 and retains the original particle morphology. The FePO4 obtained can be synthesised into LiFePO4/C by direct regeneration process or impurity removal regeneration process. The material synthesized by the latter process has a better electrochemical performance, with a discharge specific capacity of 144.5 mAh/g at 1.0C and a capacity retention of 92.0% over 500cycles. The superior performance can be attributed to an impurity removal process that reduced agglomeration and improved particle morphology.

Sulfur impurity removal in magnesium aluminate spinel by acid treatment

MgAl2O4 is a versatile and stable oxide that is useful in various applications. However, the presence of impurities originating as a part of the powder synthesis process can potentially impair desired properties. In this work, we performed acidic treatments with mixtures of HNO3 and H2SO4 on commercial MgAl2O4 nanopowders. The treated powder structure and morphology was found to be largely retained, while changes in specific surface area, adsorbed CO2, and sulfur content were detected. Two sulfur species populations were identified (i.e., S2+ and S6+) and their concentration throughout the surface and bulk of the particles was analyzed. Notably, S2+ was beforehand unknown as a contaminant in MgAl2O4. The S2+ concentration could be diminished below detection limit of XPS by increasing the percentage of H2SO4. The insights gained on sulfur impurities present in commercial nanopowders and their removal possibilities or limitations can help utilize such oxides in applications sensitive to chemical purity.

As Fast As We Can: Rational Design of Rapid Chimeric Antigen Receptor T Cell Manufacturing

Background Chimeric antigen receptor T cell proved to be a promising approach to treat hematological malignancies. There are six autologous CAR-T drugs approved by FDA in US. The production of autologous CAR-T cells is carried out by a time-consuming manufacture process typically need 2-3 weeks. Unfortunately, about 25% patients died while awaiting their CAR-T product. Rapid manufacturing CAR-T cells still is an unmet clinical need for fast processing diseases. We developed the “DASH CAR-T” manufacturing platform which harvested CAR-T cell in two-three days. Our first product, autologous DASH CD19 CAR-T demonstrated greater anti-tumor efficacy in murine study correlated with higher T cell expansion compared with conventional CAR-T. In this study, we designed a simplified novel CAR-T manufacturing process with optimized culture and harvest time between 48 hours to 72 hours. Methods Rapid manufacturing CAR-T cells comprising common key steps as the conventional CAR-T product : select T cells from PBMC, activated T cells by CD3/28 Dynabeads, transduced with retroviral vector expressed CD19-28z CAR construct, and then the CAR-T cells harvested and cryopreserved for clinical use. We investigated the shortest time for each steps by various reagents, medium and process. Then we compressed the whole process and our novel approaches completed all manufacturing process less than 72 hours. Results First, we compared the harvest timing based 3 batches CAR-T cells from health donors. A various factors, such as cell viability, CD3+%, Annexin V-/PI- population, percentage of residual CD19+ cells, and naïve T cell proportion were very similarly between 48 hours CAR-T cells and 72 hours CAR-T cells, indicated comparable harvest timing for manufacture. Second, we investigated 3 batches of CAR-T cells manufactured from B cell malignancy patients. In this scenario, 72 hours CAR-T exhibited better cell viability, increased naïve T cell population, and more Annexin V-/PI- cells in the culture compared to 48 hours CAR-T. The different performance of patient cells and healthy donor cells suggested the importance of the choice of starting material for process development of cell therapy. All batches successfully manufactured in 72 hours. Tumor cell-xenograft NOG mice models were confirmed the anti-tumor activity of DASH CD19 CAR-T cells in vivo. Conclusions This study reported an optimized DASH CAR-T process with 48 hours and 72 hours manufacturing. Cell viability, stemness of T cells, CAR expression, and removal of impurity were improved in the CAR-T product manufactured by this novel process. Based on the preclinical study results, an investigator-initiated trial (IIT) has launched to explore the safety, efficacy, pharmacokinetic/pharmacodynamics characteristics in patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL).

Efficient Synthesis of Nickel-Molybdenum/USY-Zeolite Catalyst for Eliminating Impurities (N, S, and Cl) in the Waste Plastic Pyrolysis Oil: Dispersion Effect of Active Sites by Surfactant-Assisted Melt-Infiltration

The upgrading of waste plastic pyrolysis oil (WPPO) through hydrotreating (HDT) is crucial for transforming plastic waste into chemical feedstock. The catalytic role of HDT is of paramount importance for this conversion procedure. In this study, bimetallic catalysts based on Ni and Mo were prepared using the surfactant-assisted melt-infiltration (SAMI) method, completely omitting the use of liquid solutions. Thorough analysis via X-ray diffraction, transmission electron microscopy, and hydrogen temperature-programmed reduction confirmed that the addition of Span60 surfactant effectively prevented the aggregation of Ni and Mo components, reduced the size of metal particles, and improved the dispersion of active sites on the zeolite supports. Consequently, NiMo-based catalysts incorporating Span60, synthesized using the SAMI method, exhibited a superior catalytic performance in the removal of nitrogen, sulfur, and chloride impurities from WPPO during HDT compared to those without surfactant. Specifically, the catalyst prepared with Span60 exhibited 15% higher nitrogen conversion compared to the catalyst prepared without Span60.

Effective adsorptive removal of trace CO2 from olefin using alkanolamine‐polyethylenimine‐functionalized fumed silica

AbstractThe purification of gaseous olefins, such as C2H4 and C3H6, requires the efficient removal of trace CO2 impurities. However, the development of ideal adsorbents with high CO2/olefin selectivity has remained a challenge. In this study, we synthesized a novel adsorbent, denoted as PEI/DEA@FS, by modifying fumed silica (FS) with a combination of polyethylenimine (PEI) and diethanolamine (DEA). At 298 K and 0.0004 bar, PEI/DEA@FS presented the highest CO2 adsorption capacity among previously studied adsorbents, with a value of 2.12 mmol/g. Notably, PEI/DEA@FS demonstrated very high ideal adsorption solution theory selectivity for CO2/C2H4 (>1010) and CO2/C3H6 (>107) at 298 K and 0.01 bar. Breakthrough experiments revealed its excellent separation performance, producing olefins (C2H4 and C3H6) with ultra‐high purity (>99.9%) from a CO2/olefin (1/99) mixture. Moreover, PEI/DEA@FS exhibited outstanding stability over 20 adsorption and desorption cycles, and its CO2 adsorption performance remained almost unchanged under 75% relative humidity in the feed stream.

Removal of Low-Content Impurities from Pure Al by Supergravity Combined with Semi-Solid Method

Recently, the purification technology for high-purity aluminum (Al) has become the focus and difficulty of the majority of researchers. In this study, a novel approach for removing iron (Fe) impurities from pure Al via combining the supergravity field and semi-solid refining was proposed. Various separation temperatures (T), holding times (th), and separation times (ts) were applied within a gravitational field to explore their impact on the purification process and its underlying mechanisms. The optimal conditions were achieved at T = 653 °C, th = 40 min, ts = 3 min, and a gravity coefficient G = 1000, with the loss rate of purified Al reaching up to 4.1% and the removal rate of Fe reaching 81.9%. The Fe content in pure Al was reduced from 0.32 wt.% to 0.06 wt.%. Moreover, the purified mechanism of supergravity in a semi-solid method was reported for the first time. It was concluded that supergravity could decrease the value of the effective distribution coefficient (ke), thereby promoting the continuous migration of Fe impurities at the solidification interface into the liquid phase. The Fe-rich phase in the Al melt was completely filtered to the lower part of the crucible in the supergravity field, completing the further purification of the pure Al.

Effect of Melt Superheating Treatment on the Microstructures and Purity of a Directionally Solidified Superalloy

In this paper, the effects and the mechanisms of melt superheating treatment (MST) on a directionally solidified alloy were investigated. The mass loss rate of the superalloy becomes severe as the MST temperature rises. The chromium, tantalum, and hafnium are the primary evaporation elements during MST. As the MST temperature increases from 1500 to 1600 °C, the secondary dendrite arm spacing is reduced by 13.3%, and the average size of γ′ particles are reduced by 11.5% and 18.2% in the dendrite core and inter-dendritic area, respectively. The content of oxygen and nitrogen gradually reduces with the increase in the MST temperature. However, the sulfur content is not significantly affected by the MST temperature. The essential cause of γ′ phases transition is supposed to be the MST-induced changes in solute distribution and the decomposition of atomic clusters. In addition, the nitrides and Ti (N, C)-type carbides are continuously dispersed as the MST temperature increases, which promotes the removal of nitrogen impurities.

Recovery of tungsten from spent selective catalytic reduction catalyst by sulfuric acid precipitation and evaporation crystallization method

AbstractBACKGROUNDSelective catalytic reduction (SCR) can effectively handle NOx from flue gas in coal‐fired power plants. However, as the core part of the SCR method, V2O5–WO3/TiO2 catalyst has a limited operational life in the complex flue gas environment. The recovery of rare metals from spent catalyst would not only bring economic benefits but also solve environmental problems. The process of reducing acid leaching and further roasting‐water leaching could realize the efficient recycling of vanadium, tungsten and titanium.RESULTSAfter reducing acid leaching and roasting‐water leaching to treat spent SCR catalyst, the obtained solution containing tungsten was used as the raw material in this study. The optimal pH value of solution for removal of silicon and aluminum impurities was 9.2–9.5. The best tungsten precipitation conditions were shown as follows: a tungsten concentration of 30 g L−1, a sulfuric acid concentration of 8 mol L−1, reaction temperature of 70 °C and reaction time of 2 h. Under the optimal tungsten precipitation conditions, the tungsten precipitation efficiency can reach 92.53%. Finally, in order to further improve the purity of the crude H2WO4, the crude H2WO4 was fully dissolved in ammonia, followed by filtration and evaporation crystallization to obtain 5(NH4)2O.12WO3.5H2O (APT) crystals with a purity of 93.05 wt%. The crystallization efficiency of APT was 73.37% at 60 °C for 2 h with a rotor speed of 400 rpm.CONCLUSIONThese results indicated that a higher purity of APT crystals can be obtained by the steps of removing silicon and aluminum, precipitation of tungsten by sulfuric acid, ammonia dissolution and evaporation crystallization. © 2023 Society of Chemical Industry (SCI).

High-quality separation and recovery of nylon and dyes from waste carpet via non-destructive dissolution and controlled precipitation for sustainable recycling

Pure recycled nylon fibers were developed for the first time from carpets without environmentally irresponsible dye destruction and costly polymer degradation. The lack of economically viable separation technology has resulted in more than 97 % of carpets ending up in landfills, posing severe environmental and health concerns. A sustainable and cost-effective separation and purification technology is the key to successful carpet recycling on a large scale. Impurities removal via depolymerization, although technically feasible, faces intolerable economic challenges, limiting its large-scale application. Cost-effective spinning of dye-containing nylon into fibers did not work since acid dyes considerably lowered the crystallinity and mechanical properties of re-spun fibers. Here, we present a closed-loop recycling approach involving controlled dissolution and precipitation (ReNylon via D&P), allowing for the complete separation of nylon and dyes without damaging their chemical structures. The non-destructive dissolution in butanediol completely removed the colored nylon fibers from both the face and back of carpets. The temperature-induced precipitation resulted in colorless amorphous nylon separated from acid dye solution. Recycled colorless fibers from purified nylon demonstrated the same quality as fibers before the recycling. Acid dyes from carpet were redyed onto nylon in an energy-conservative butanediol-based solution and showed identical dyeability and colorfastness to virgin dyes. The overall costs based on preliminary estimation to produce nylon fibers via our recycling is less than 23 % of that via the petroleum-based method, indicating a high economic viability of the recycling. This clean recycling process minimized waste generation by recovering more than 99 % of biodegradable and low-toxic butanediol. The recycling technology could also apply to other textile blends for closed-loop circulation.

OMNI: Gas Chromatograph Captures Seven Common PET Radiotracer Analytes in under 5 Minutes.

A novel gas chromatography method was developed using automatic injections to identify and quantify the amount of residual solvents or analytes in samples of fluorine-18 and carbon-11 radiopharmaceuticals. This approach evaluates seven analytes in less than 5 versus 13 min of acquisition time. The method additionally includes a 3 min bakeout to aid in the removal and carry-over of higher-boiling impurities. Chromatographic parameters such as column temperature, hold time, column pressure, flow rate, and split ratios were adjusted and optimized to analyze radioactive drug samples containing analytes which include methanol, ethanol, acetone, acetonitrile, triethylamine, N,N-dimethylformamide, and dimethyl sulfoxide. The relative standard deviation for each solvent was determined to be no greater than 1.6%. The method limit of detection (LOD) and limit of quantification (LOQ) were between 0.053 and 0.163 and 0.000 (5.791 × 10-6) and 0.520 mg/mL, respectively. This GC technique, using flame ionization detection (FID), was validated and is currently employed for the routine quality control of all approved IND and RDRC PET radiopharmaceuticals at our center.

Removal of impurities from Metallurgical silicon by adding ZnO and BaO to the CaO–SiO2 slag system

One of the essential techniques for eliminating metallurgical silicon impurities during a metallurgical process is slag refining. In the present investigation, BaO and ZnO were added to a binary slag system composed of CaO–SiO2 in weight percentages that varied from 5 to 20 %, and the effects of various slag system compositions, Slag-Si mass ratios (slag-silicon ratios), and refining times on the content of metallurgical silicon impurities were investigated. The mass transfer coefficients βAl and βB for Al and B were 3.01×10−6m·s−1, 6.80×10−7m·s−1, respectively, and the apparent rate constants (kB, kAl) of Al and B obtained for the refining time were 3.84×10−4s−1 and 8.67×10−5s−1, respectively, The experimental results show that in the slagging refining process, the loss rate of silicon increases slightly with the extension of the refining time and is much smaller than that of the blowing refining, so it can be considered to be a more superior method of removing impurities from industrial silicon.

Properties of Carbon Dots versus Small Molecules from "Bottom-up" Synthesis.

A major challenge in the "bottom-up" solvothermal synthesis of carbon dots (CDs) is the removal of small-molecule byproducts, noncarbonized polyamides, or other impurities that confound the optical properties. In previously reported benzene diamine-based CDs, the observed fluorescence signal already has been shown to arise from free small molecules, not from nanosized carbonized dots. Here we have unambiguously identified the small-molecule species in the synthesis of CDs starting with several isomers of benzene diamine by directly matching their NMR, mass spectrometry, and optical data with commercially available small organic molecules. By combining dialysis and chromatography, we have sufficiently purified the CD reaction mixtures to measure the CD size by TEM and STM, elemental composition, optical absorption and emission, and single-particle blinking dynamics. The results can be rationalized by electronic structure calculations on small model CDs. Our results conclusively show that the purified benzene diamine-based CDs do not emit red fluorescence, so the quest for full-spectrum fluorescence from isomers of a single precursor molecule remains open.

Removing boron from the diamond wire saw silicon powder by MgF2-sintering synergized with Na2CO3-enhanced refining to prepare low-boron silicon

Recycling environmentally hazardous diamond wire saw silicon powder (DWSSP) to prepare low-boron silicon is crucial for environmental pollution and waste resources recycling. For reutilization, the decomposition of impurity-containing SiO2 layers and the removal of boron are the two main issues that need to be addressed. Therefore, the addition of MgF2 to DWSSP for sintering to damage the containing-impurities SiO2 layers and remove harmful boron was first studied. The results showed the SiO2 layer was effectively decomposed by reaction with MgF2 and the removal rate of harmful boron impurity was 86.9 % at 1300 °C for 120 min with 20 % MgF2 addition. Subsequently, the effect of Na2CO3 on the removal of boron impurity in the refining process was analyzed, finding that 10 % Na2CO3 addition enhanced the boron removal rate to 95.6 % at 1600 °C for 60 min with CaO/SiO2 ratio of 1.2. Finally, the removal mechanism of harmful B impurities via MgF2-sintering synergized with Na2CO3-enhanced refining was analyzed. This work provides a simple and feasible alternative for recycling DWSSP to prepare low-boron silicon as feedstock for solar-grade silicon preparation.