High-purity Production Research Articles

Improving the Long-term Enantioselectivity of a Silicon-Carbon Bond-Forming Enzyme.

Enantioselectivity is a key advantage of enzymatic catalysis. Understanding the most important factors influencing enantioselectivity necessitates thorough investigation for each specific enzyme. In this study, we explore various approaches to optimize reaction conditions for organosilicon production using an immobilized Cytochrome C recently tailored via directed evolution. Over extended reactions, this enzyme experiences a loss of enantioselectivity. Mass spectrometry (MS) revealed covalent modifications on the enzyme, but mutating the respective amino acids did not restore enantioselectivity. Nuclear magnetic resonance (NMR), along with a detailed comparison of the influence of reaction components such as cosolvents and reducing agents, indicated significant conformational changes in the presence of the diazo ester substrate. Additionally, we identified sodium ascorbate as a suitable and milder reducing agent compared to the previously used sodium dithionite, ensuring anaerobic conditions for silicon-carbon bond formation. Ultimately, maintaining a high enzyme-to-substrate ratio in the reaction was found to be crucial for achieving high enantiomeric purity of the organosilicon product over four days in sequential, repetitive batch reactions, thus improving the previously established reaction system. The methods and findings presented here are particularly valuable for addressing enantioselectivity issues in other enzymes that operate with diazo compounds as the substrates in carbene-transfer reactions.

High-Purity Ethylene Production from Ethane/Ethylene Mixtures at Ambient Conditions by Ethane-Selective Fluorine-Doped Activated Carbon Adsorbents.

Energy-efficient separation of light alkanes from alkenes is considered as one of the most important separations of the chemical industry today due to the high energy penalty associated with the applied conventional cryogenic technologies. This study introduces fluorine-doped activated carbon adsorbents, where elemental fluorine incorporation into the carbon matrix plays a unique role in achieving high ethane selectivity. This enhanced selectivity arises from specific interactions between surface-doped fluorine atoms and ethane molecules, coupled with porosity modulation. Consequently, an equilibrium ethane/ethylene selectivity of as high as 3.9 at 298 K and 1 bar was achieved. Furthermore, polymer-grade ethylene (purity >99.99%) with a productivity of 1.6 mmol/g was obtained in a breakthrough run at ambient conditions from a binary ethane/ethylene (1/9 v/v) mixture. The ethane selectivity of the fluorine-doped carbons was further elucidated through Monte Carlo simulations and density contours of the adsorbed components. In addition to the high ethane selectivity, the adsorbents exhibited a hydrophobic surface, high stability under moisture, and excellent regenerability over multiple adsorption-desorption cycles under both equilibrium and dynamic conditions, demonstrating a sustainable performance.

Dehydration-enhanced Ion Recognition of Triazine Covalent Organic Frameworks for High-resolution Li+/Mg2+ Separation.

The precise and rapid extraction of lithium from salt-lake brines is critical to meeting the global demand for lithium resources. However, it remains a major challenge to design ion-transport membranes with accurate recognition and fast transport path for the target ion. Here, we report a triazine covalent organic framework (COF) membrane with high resolution for Li+ and Mg2+ that enables fast Li+ transport while almost completely inhibiting Mg2+ permeation. The remarkably high rejection of Mg2+ by the COF membrane is achieved via imposed ion dehydration and the construction of the energy well. The proper hydrophilic environment of the COF channel promotes the dissociation of Li+ from the negatively charged functional groups, allowing Li+ for hopping transport supported by the sulfonate side-chains to shorten the diffusion path of Li+. Under high-salinity electrodialysis conditions, the COF membrane demonstrates robust Li+/Mg2+ separation performance (No Mg2+ were detected in the collected solution), achieving efficient lithium recovery and high product purity (Li2CO3: 99.3%). This membrane design strategy enables high energy efficiency and powerful lithium extraction in the electrodialysis lithium extraction process, and can be generalized to other energy and separation related membranes.

High-level biosynthesis and purification of the antimicrobial peptide Kiadin based on non-chromatographic purification and acid cleavage methods

Antimicrobial peptides (AMPs) are renowned for their potent bacteriostatic activity and safety, rendering them invaluable in animal husbandry, food safety, and medicine. Despite their potential, the physiological toxicity of AMPs to host cells significantly hampers their biosynthetic production. This study presents a novel approach for the biosynthesis of the antimicrobial peptide Kiadin by engineering a DAMP4–DPS–Kiadin fusion protein to mitigate host cell toxicity and achieve high-level expression. Leveraging the unique properties of the DAMP4 protein, we developed a non-chromatographic purification method to isolate the DAMP4–DPS–Kiadin fusion protein with high purity. The instability of the D–P peptide bond under acidic conditions, combined with the thermal and saline stability of DAMP4, enabled efficient separation of Kiadin through acid cleavage and isoelectric precipitation, yielding Kiadin with 96% purity and a production yield of 29.3 mg/L. Our optimization of acid cleavage temperature, duration, and isoelectric precipitation conditions proved critical for maximizing the purification efficiency and expression levels of Kiadin. The biosynthesized Kiadin exhibited robust bacteriostatic activity against Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Bacillus cereus and Staphylococcus aureus. Notably, Kiadin demonstrated significant post-antibiotic effects by disrupting bacterial membrane integrity, inducing cytoplasmic leakage, and inhibiting biofilm formation in E. coli K88 and S. aureus Mu50, without cytotoxicity towards mouse macrophages. In vivo studies further confirmed Kiadin's exceptional therapeutic efficacy against abdominal infections caused by E. coli K88. The acid cleavage and non-chromatographic purification techniques developed in this study offer a cost-effective and efficient strategy for the high-purity production of AMPs.

High-purity H2 production from biomass through cascade processes based on alkaline thermal treatment

A cascade process consisting of three techniques of alkaline thermal treatment, catalytic steam reforming, and alkali absorption is introduced to produce high-purity H2. The effect of NaOH and biomass molar ratio is investigated for H2 production, and the interactions between the three components was carried out specially to investigate the effect on H2 and CH4 production for the alkaline thermal treatment of real biomass. Synthesized mesoporous 10 wt% Ni/Al2O3 catalyst is applied in steam reforming of CH4. The NaOH supported on CaO was used for the absorption of CO and CO2 during the alkali absorption process. The results show that the high H2 production of 68.04 mmol·g-1 cellulose with a purity of 99.93 vol.% is achieved under optimized conditions. The cascade process for sawdust results in a 103% increase in H2 production compared with one-step alkaline thermal treatment, and the H2 purity is greater than 99.9 vol.%.

Utilizing NCP@PO(OH)2 as a Core-Shell Magnetic Nano-Catalyst for the Conversion of β-Hydroxy Nitrile to α,β-Unsaturated Carboxylic Acid

The synthesis of α,β-unsaturated compounds is crucial in organic chemistry, especially in drug discovery and pharmaceutical development. In this study, NCP@POCl<sub>2</sub>-x (Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>@ chitosan@POCl<sub>2</sub>-x) has been introduced as a new, environmentally friendly, and highly efficient heterogeneous magnetic nanocatalyst for the synthesis of α,β-unsaturated carboxylic acids. This catalyst facilitates the <i>in situ</i> transformation of POCl<sub>2</sub>-x to PO(OH)<sub>2</sub> in the presence of water, effectively converting β-hydroxy nitriles into α,β-unsaturated carboxylic acids through a specific mechanism involving water and heat. The reactions display notable regioselectivity, leading to high-purity products and quantitative yields. NCP@PO(OH)<sub>2</sub> exhibits heterogeneity, magnetic properties, straightforward recovery, and outstanding performance, making it a valuable catalyst for efficient and selective transformations of β-hydroxy nitriles. Additionally, it can be easily separated from the mixture of reactions using external magnetic forces.

Improving Process Design for Reaching Energy Efficiency, Environmentally Friendly, and Producing High Purity Methyl Chloride of Dehydrochlorination Process of Methanol and Hydrogen Chloride

Methyl chloride, also known as chloromethane, plays a vital role in producing various industrial goods. The current demand for methyl chloride in Indonesia exceeds production levels, making the design of a methyl chloride plant essential. This research focuses on improving methyl chloride production economically and operationally by exploring plant design using simulations that emphasize energy efficiency and high purity. The objective of this research is to develop a process design for producing methyl chloride from methanol and hydrogen chloride, aiming for energy efficiency, an environmentally friendly factory, and high-purity methyl chloride products. The research employed an iterative simulation method to compare the basic and modified processes for methyl chloride production. The process involved constructing a simulation model using Aspen HYSYS, analyzing the simulation results using Aspen Energy Analyzer V12, and iteratively adjusting process parameters until achieving the desired performance or results. The research findings indicate that the methyl chloride modification process exhibits a lower energy requirement compared to the methyl chloride base process. Moreover, the modification process demonstrates minimal carbon emissions, establishing it as a sustainable and environmentally friendly design. Additionally, the methyl chloride produced in the modification process achieves a higher percentage of purity. In the initial process, the methyl chloride purity stood at 98.17%, while in the modified process, it saw an elevation to 99.35%. Considering these three aspects, the modification process is conclusively more efficient than the basic process system. Copyright © 2024 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Supercritical Ethane Processing of ZIF-8 Membranes towards Pressure-Resistant C3H6/C3H8 Separation.

ZIF-8 membranes have shown great promise in industrial-scale C3H6/C3H8 separation. Nonetheless, sustainable preparation of pressure-resistant ZIF-8 membranes remains a grand challenge. In this study, we pioneered the use of supercritical ethane (scC2H6) as reaction medium for preparing pressure-resistant ZIF-8 membranes. Membrane growth in neutral organic environment was proven to have less disturbance to structure integrity compared with supercritical CO2 (scCO2). Gas permeation results indicated that obtained ZIF-8 membrane exhibited an ideal C3H6/C3H8 selectivity of 172.1 with C3H6 permeance of 5.9×10-9 mol ⋅ m-2 ⋅ s-1 ⋅ Pa-1. Of particular note, the membrane maintained stable C3H6/C3H8 selectivity of ~150 with C3H6 flux of ~1.6×10-3 mol ⋅ m-2 ⋅ s-1 at operation pressure of 6 bar, which was significantly different from ZIF-8 membranes obtained from scCO2 reaction medium. Through combining with advantages of zero pollutant discharge and full ligand recovery, our protocol holds great promise in sustainable preparation of pressure-resistant ZIF-8 membranes towards practical application in high-purity C3H6 production.

Delayed linker addition (DLA) synthesis of dual linker ZIF-8 for separation mono- and di-branched isomers of hexane

The separation of mono- and di-branched C6 alkane isomers is one of the most challenging industrial processes for the production of high-octane gasoline components. In this work, ZIF-8 with dual ligands of imidazole (IM) and 2-methylimidazole (2-MIM), named as DLA-ZIF-8-IM, was synthesized by the method of delayed linker addition, and the microstructure of DLA-ZIF-8-IM was analyzed. Adsorption thermodynamic, kinetic and separation properties of C6 alkane isomers were investigated. The results show that compared with SALE-ZIF-8-IM prepared by the solvent-assisted ligand exchange method, the synthesis method of DLA-ZIF-8-IM is simpler and the BET specific surface area and pore volume (2136 m2·g−1 and 0.72 cm3·g−1) of DLA-ZIF-8-IM are increased by 21 % and 14 %, which is more conducive to adsorption and diffusion of 3-methylpentane (3MP) on DLA-ZIF-8-IM. The equilibrium adsorption capacity of 3MP on DLA-ZIF-8-IM reaches up to 2.89 mmol·g−1, which is 1.1 times than that on SALE-ZIF-8-IM, and the ratio of diffusion time constants between 3MP and 2,3-dimethylbutane (23DMB) on DLA-ZIF-8-IM (5.13) is 2.2 times than that on SALE-ZIF-8-IM. Moreover, at 30℃, the breakthrough adsorption capacity of 3MP on DLA-ZIF-8-IM is 1.46 mmol·g−1, which is 1.6 times more than that of SALE-ZIF-8-IM (0.90 mmol·g−1), while the breakthrough adsorption capacity of 23DMB is basically the same. The separation factor between 3MP and 23DMB on DLA-ZIF-8-IM is 2.96 via the synergy of thermodynamic and kinetic mechanism and the dynamic adsorption capacity of 3MP reaches 1.46 mmol·g−1. DLA-ZIF-8-IM achieves complete separation of C6 alkane mixtures for obtaining single high-purity product. This work provides a novel synthesis strategy for developing C6 alkane (clear) adsorption separation materials by modulating microporous structures of dual-ligand MOFs.

Study on the difference of composition between traditional and modern lime used in the restoration of Qufu San Kong Ancient Architectural

In recent years, a decline in the binding strength and frost resistance of lime binder used in the restoration of the Qufu San Kong ancient architectural complex in Shandong Province has been observed, which has significantly affected the quality of restoration. In this study, lime binder samples were collected from the Kuiwen Pavilion roof, limestone samples in the vicinity of the Confucius Temple, and modern industrial quicklime from various provinces in China. Analytical methods including X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy were employed. Results indicate that the local limestone in Qufu contains impurities such as Si or Mg. XRD patterns reveal that the main phase of the Kuiwen Pavilion roof lime binder samples is calcite. Using FTIR and Scanning Electron Microscope- Energy Dispersive Spectrometer (SEM-EDS), the presence of hydrated calcium silicate (C-S-H) gel is identified in the samples. This suggests that the traditional quicklime-production process in Qufu yields a multiphase composite system. Modern industrial quicklime, aged for two months, showed no presence of C-S-H gel in the FTIR spectra and SEM-EDS results, indicating that it is a comparatively pure system primarily comprising CaO. The study suggests that traditional quicklime-production processes typically involve burning limestone with higher Si content, leading to the generation of a significant amount of dicalcium silicate. Additionally, the use of high-ash coal as fuel introduces reactive silicon dioxide into the quicklime product. These factors contribute to the formation of C-S-H gel in hydrated lime. The presence of C-S-H gel enhances lime binder properties such as binding strength and frost resistance. Modern quicklime production, which selects limestone with lower Si content and employs low-ash coal as fuel, aims to minimize or avoid the formation of C-S-H gel in hydrated lime. High-purity CaO quicklime products align with the principles of modern fine processing; however, they compromise the binding strength and durability of lime binder required for traditional architectural restoration.

Reaction performance and energy consumption analysis of high-purity hydrogen production system of in-situ CO2 absorption enhanced aqueous phase reforming of methanol

High-purity hydrogen was efficiently produced through an environmentally conscious process that combines aqueous phase reforming of methanol (APRM) with in-situ CO2 absorption. By integrating La-promoted Ni-based catalysts derived from layered double hydroxides (LDHs) with CO2 capture technology, the system not only enhanced hydrogen yield but also suppressed the formation of undesired by-products. The introduction of alkali into APRM process resulted in significant increase in methanol conversion, hydrogen production rate and hydrogen concentration in gas phase product, attributed to an equilibrium shift towards the forward APRM reaction, facilitated by in-situ CO2 absorption. This shift also suppressed the methanation reaction and improved catalyst stability. Optimal conditions were identified based on the calcination temperature of catalyst, the temperature of reactions and the molar ratio of methanol to KOH in substrate. Energy consumption analysis across three different systems demonstrated that the APRM system with in-situ CO2 absorption by KOH exhibited lower energy consumption (78.87 kJ/mol-H2) and greater viability for practical applications. Future perspectives for process development are also discussed, with a focus on improving reaction efficiency, reducing energy consumption, recycling alkali, and extending catalyst life.

Challenges for Hybrid Water Electrolysis to Replace the Oxygen Evolution Reaction on an Industrial Scale

To enable a future society based on sun and wind energy, the transformation of electricity into chemical energy in form of fuels is crucial. Electrolysis offers a promising solution, achieving this transformation by splitting water. At the anode, the oxygen evolution reaction (OER) produces protons and electrons that are used at the cathode for the hydrogen evolution reaction (HER) to generate hydrogen fuel. While hydrogen is the desired product, oxygen has limited economic value. From a techno-economic standpoint, a more attractive approach is hybrid water electrolysis, which replaces the OER with value-added oxidation reactions of abundant organic feedstocks.However, significant challenges stand in the way of widespread adoption of hybrid water electrolysis for large-scale industrial applications. This work provides a critical analysis of these hurdles, delving deeper into each aspect:Higher Kinetic Overpotentials for Organic Oxidation Reactions: Compared to the well-established OER, organic oxidation reactions generally have a lower energy consumption, but generally necessitate greater overpotentials to overcome kinetic limitations. Addressing this challenge requires the development of novel electrocatalysts that can significantly reduce the activation energy for organic oxidation reactions, bringing their kinetic performance closer to that of the OER.Limited Availability and Product Demand of Feedstocks and Products: The organic feedstocks suitable for these reactions may be less abundant or have a lower market demand compared to hydrogen (or even CO2 reduction). This scarcity or limited economic value of the organic substrates and products can potentially hinder the overall economic viability of hybrid water electrolysis. Extensive research into utilizing readily available and sustainable organic feedstocks is crucial. Additionally, exploring and developing markets for the products generated from these oxidation reactions would be necessary for widespread adoption.Additional Purification Needs: The products formed during organic oxidation reactions might require further purification steps to meet the specifications required for downstream applications. These additional purification processes add complexity and increase the cost associated with hybrid water electrolysis. Developing selective electrocatalysts that generate the desired products in high purity could significantly alleviate this challenge.High Activity: The catalysts should possess a high intrinsic activity for the target organic oxidation reactions, ensuring fast reaction rates and maximizing product yield.Selectivity for the Desired Products: Indiscriminate oxidation of the organic feedstock can lead to the formation of undesired byproducts, reducing the efficiency and necessitating complex downstream separations. Therefore, catalysts with high selectivity for the targeted products are essential.Long-Term Stability: Electrocatalysts must maintain their activity and selectivity over extended periods under operating conditions. Degradation of the catalysts can occur due to various factors, including chemical and structural transformations during operation. Developing electrocatalysts with exceptional long-term stability is paramount for the practical application of hybrid water electrolysis.By outlining these challenges, we aim to stimulate discussion and guide research efforts within the academic community. Addressing these critical aspects is essential to pave the way for the successful implementation of hybrid water electrolysis at an industrial scale, ultimately enabling a sustainable energy future.Kahlstorf, J. N. Hausmann, T. Sontheimer, P. W. Menezes, Challenges for Hybrid Water Electrolysis to Replace the Oxygen Evolution Reaction on an Industrial Scale. Global Challenges 2023, 7, 2200242. Figure 1

(Digital Presentation) Electrochemical Synthesis of Chromium Carbide Coatings on the Surface of Carbon Fibres in NaCl-KCl-CrCl3-Cr Melt and Study of Their Electrocatalytic Properties

Composite materials based on carbides of refractory metals are of exceptional interest in various fields of application. They have unique characteristics such as high hardness, catalytic activity [1,2], etc. They are widely used in industry due to their high corrosion and oxidation resistance at high temperatures. Chromium carbide can be produced in various ways, for example, the most common method of production is physical deposition from the gas phase (PVD coating). Other synthesis methods are not so popular, but they are also widely known (electron beam surfacing, plasma arc welding, etc.). These methods have both advantages and disadvantages. Refractory metal carbide coatings obtained by electrochemical methods in molten salts have a number of advantages, such as the possibility of obtaining homogeneous coatings on products with complex shape, low porosity of coatings, high adhesion to the substrate.Coatings of refractory metal carbides on a developed surface can also be used as electrocatalytic systems in reducing and oxidizing reactions. At the same time, the advantage of using electrocatalysis is the possibility of carrying out various reactions in a wide range of conditions from an extremely reducing environment to an extremely oxidizing one, the ability to control the route of the reaction by precisely adjusting the potential. Unlike common catalysis, electrocatalytic reactions do not leave reagents in the form of oxides, hydroxides or salts in the products. In electrochemical processes, an electron acts as a reducing agent, therefore high purity products are formed.The purpose of this study was the electrochemical synthesis of chromium carbide in molten salts on a substrate made of carbon fibres Carbopon-B-22, as well as the study of electrocatalytic properties of the obtained composites.To precipitate chromium onto a carbon substrate, a non-pressure transfer method in a molten equimolar mixture of NaCl and KCl containing 20 wt.% CrCl3, which is in contact with metallic chromium, was used. The synthesis of chromium carbides was carried out at temperatures of 1123 and 1223 K for 8-16 hours.To study the kinetics of the electrocatalytic decomposition of hydrogen peroxide on the surface of carbon fiber–synthesized chromium carbides, a method based on measuring the volume of the released oxygen gas was used [3,4]. The initial carbon fiber Carbopon-B-22 was used as the cathode, and a carbon fiber electrode with Cr3C2 and Cr7C3 chromium carbides coatings was used as the anode.In this study, two integral methods were used to determine the order of the hydrogen peroxide decomposition reaction: the substitution method (calculation of reaction rate constants according to equations for different reaction orders) and graphical (plotting of various concentration dependences on time and determining the linear dependence of one of them). The reaction rate constant was determined by the slope tangent of the straight line in the corresponding coordinates.The activation energy of the process was calculated based on experimental data obtained at different temperatures.References Stulov Yu., Dolmatov V., Dubrovskiy A. and Kuznetsov S. Electrochemical synthesis of functional coatings and nanomaterials in molten salts and their application // 2023. V. 13. 352.Dolmatov V.S., Kuznetsov S.A. Synthesis of Refractory Metal Carbides on Carbon Fibers in Molten Salts and Their Electrocatalytic Properties // Journal of The Electrochemical Society. V. 168. 122501.D. G. Miklashov, V. S. Dolmatov and S. A. Kuznetsov The currentless synthesis of tantalum and niobium carbide coatings on the carbon fibers and their electrocatalytic activity for the hydrogen peroxide decomposition reaction J. Phys.: Conf. Ser. 1281 012054.Yang G., Chen F., Yang Z. Electrocatalytic Oxidation of Hydrogen Peroxide Based on the Shuttlelike Nano-CuO-Modified Electrode // Inter. J. Electrochem. – 2011. – № 2012. – P. 1-6.

(Digital Presentation) 2D Transition Metal Borides: Different Etchants for Al Removal from MAB and Application in Cd2+, Pb2+, Cu2+ and Hg2+ Sensing

Despite significant progress in MBene research, achieving perfect layered structures and high purity under different etching conditions remains challenging. Additionally, their potential for heavy metal ion detection in electrochemical applications is underexplored. The synthesis of MBenes, particularly MoB, involves removing Al precursor MoAlB. Recent advancements focus on high-temperature solid-state etching using Lewis bases or chemical wet etching, with wet etching proving more economical, milder, and higher purity products. This study compares various non-fluoride etchants' effects. Ammonium persulfate (APS) achieved a significant etching rate of ~71% for Al, resulting in restacked accordion-like multilayered MBene. However, high temperatures led to stable, insoluble AlxO, reducing product purity. CuCl₂ etching yielded a lower rate of ~54%, producing flake structures with copper impurities. Acid etching resulted in a perfect layered structure but lower purity, while alkali etching provided similar etching rates to APS with the highest purity. Complete Al removal at elevated temperatures caused the loss of the layered structure. Maintaining a small amount of Al during hydrothermal etching supports the layered structure, and subsequent room-temperature etching produces fluffy open-layered MBene MoB (OL-MBene).Electrochemical studies revealed that OL-MBene-modified GCE exhibited excellent performance in detecting Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺ ions individually and simultaneously, with high sensitivity and selectivity. Notably, the sensor exhibited superior performance for Cu²⁺ and Pb²⁺ ions. The varying adsorption energies of these ions explain the differences in sensitivity and selectivity, and Pb²⁺ demonstrated the highest sensitivity due to its lowest adsorption energy on the MBene surface. Competitive adsorption studies indicated that Pb²⁺ competes with Hg²⁺ for adsorption sites while having minimal impact on Cd²⁺ and Cu²⁺ adsorption. This research advances our understanding of MBene synthesis and characterization, introducing a new avenue for leveraging MBenes in sensitive and selective electrochemical sensors for environmental monitoring. Figure 1

Bifunctional Cofe-Spinel@Cu for Peroxymonosulfate Activation and Electrochemical Nitrate Reduction Towards High Purity Ammonia Production

Ammonia is a valuable chemical feedstock and energy carrier with lower corbon footprint during conversion to H2. Haber-Bosch process is the predominant method for industrial NH3 production, but it is associated with high energy consumption and substantial CO2 emission. Recently, electrochemical nitrate reduction reaction (NO3RR), powered by renewable energy in ambient condition, has emerged as a promising method for sustainable NH3 production from nitrate containing wastewater. However, the purity of generated NH3 by NO3RR is also a critical issue that has been overlooked in state-of-the-art reports. In the case of nuclear and steelmaking wastewater, abundant nitrate ions and organic pollutants coexist. Therefore, additional step is required to separate the NH3 generated by the NO3RR from the wastewater matrix. Herein, we designed a coupled NO3RR-PMS activation electrocatalytic system to achieve a high-purity NH3 production. CoFe-spinel on Cu foam (CoFe/CF) was employed both as a cathode for NO3RR and catalyst for chemical PMS activation. The CoFe-spinel was prepared through a straightforward hydrothermal deposition on Cu foam, followed by cathodization in nitrate solution. It achieved 90% faradaic efficiency for NO3 --to-NH3 conversion and NH3 production rate of 1.10 mmol h-1 cm-2 at -0.4 V RHE, together with long-term durability for about 150 h (in 0.1 M nitrate solution at pH 14). Additionally, it demonstrated approximately 90% efficiency in removing organic pollutants via PMS activation (with 10 mg L-1 SMX solution at pH 14). Thus, the coupled NO3RR-PMS activation system, utilizing the CoFe/CF catalyst, produced NH3 with a high purity. The cathodization step generated CoFe2O4 nanostructure with well-developed oxygen vacancies, to provide plentiful active hydrogen for the observed cutting-edge figures of merit for NO3 --to-NH3 conversion. Operando analysis based on X-ray absorption spectroscopy is ongoing to reveal the genuine active site for PMS activation or NO3RR. The proposed system would offer an efficient technology for high-purity NH3 production from nitrate wastewater.

225Aс/213Bi generator for direct synthesis of 213Bi-labeled bioconjugates

Background213Bi is a short-lived radionuclide currently trialed for alpha therapy of various oncological diseases. A serious obstacle to the wide medical use is decay losses of 213Bi during a conventional synthesis of radiopharmaceuticals. In this work, we aimed to develop a two-column 225Aс/213Bi generator providing the accumulation of 213Bi separately from the parent 225Ac via continuous circular separation and decay of intermediate 221Fr. When attaining the transient equilibrium, 213Bi could be promptly extracted from the generator with an appropriate complexing agent, including chelator-protein bioconjugates. MethodsSorption behavior of Bi(III) ions onto the cross-linked dextran gel Sephadex G-25 was studied from solutions of hydrochloric and nitric acid, and from sodium chloride, sodium acetate and DTPA solutions. A bifunctional chelating agent p-SCN-Bn-DTPA was conjugated to an antibody Nimotuzumab specific to the epidermal growth factor receptor, and the procedure of 207,213Bi-DTPA-Nimotuzumab synthesis in the dextran gel medium was developed. The parameters of 225Aс/213Bi generator system were evaluated. ResultsThe weight distribution ratios of Bi(III) adsorbed onto the Sephadex G-25 gel were obtained. Up to 85 % of 213Bi was accumulated in the second Sephadex-filled column of 225Aс/213Bi generator after four-hour circulation of 0.15 M NaCl (pH 5.5) solution. Having passed the solution of DTPA-Nimotuzumab bioconjugate through the second column, a fraction of 213Bi-DTPA-Nimotuzumab radioimmunoconjugate was produced with the radiochemical yield of 64 % ± 3 % (n = 6). High radionuclidic and radiochemical purity of product was achieved. ConclusionsThe circulating 225Aс/213Bi generator provides a 213Bi-labeled bioconjugate as a final product. While a conventional synthesis route including generator milking, bioconjugate labeling and size-exclusion purification takes >20 min, the duration of 213Bi-DTPA-Nimotuzumab production by the method proposed in this work is reduced to 6–8 min.

Dynamic Modeling of Polymer Electrolyte Membrane Water Electrolysis System and Dynamic Response

Water electrolysis to produce hydrogen using electric energy is classified into polymer electrolyte water electrolysis, alkaline water electrolysis, solid oxide water electrolysis, and anion exchange membrane water electrolysis according to the type of electrolyte applied. Among them, polymer electrolyte membrane water electrolysis has a lower operating temperature than other types of water electrolysis, and it is possible to operate high-efficiency, high-power density hydrogen production with high current density. In addition, polymer electrolyte water electrolysis has the advantage of fast response to changes in power supply, so empirical studies for green hydrogen production linked to renewable energy are being conducted most actively compared to other water electrolysis. However, research on coupling polymer electrolyte water electrolysis with renewable energy generation with intermittent and irregular power generation has mainly focused on materials, cells, and stacks. In order to keep the hydrogen production reaction of water electrolysis stack stable under the condition of supply power fluctuation, the peripheral devices should be optimally installed and controlled.In this study, a dynamic model of a polymer electrolyte water electrolysis system was developed using Aspen HYSYS®. To accurately predict the hydrogen production efficiency, a stack model considering electrochemical reactions and crossovers through the electrolyte was developed and internalized in a spread sheet. A heat exchanger model from the model library was used to simulate dynamic changes in the electrolyte temperature flowing through the water electrolysis stack. The developed stack model was extended to a system model by integrating the feed pump, separator, condenser, heater, and cooling system. The developed water electrolysis system model was simulated in connection with power ramp variations and renewable energy output, and the optimal operation strategy of each module unit was derived to ensure the stability of high-purity hydrogen production under transient conditions.

Direct Electrochemical Conversion of Amine-Captured CO2 into High Concentrated C1 Products

Electrochemical CO2 conversion (eCO2R) into value-added products presents a promising strategy for mitigating global warming. However, this technology faces a significant challenge: supplying high-purity CO2 and purifying the product requires a substantial amount of thermal energy, as most systems typically use highly concentrated CO2 as a reactant. Herein, we suggested a new concept of system that bypasses energy-intensive conditioning by directly converting amine-captured CO2 into highly concentrated syngas and formic acid, using a novel amine-type CO2 absorbent, triethylamine (TREA). Our experiments show that the CO2 absorption rate (>84%) of TREA is comparable to conventional alkanolamine, with the majority of CO2 captured as bicarbonate‒a form preferred for direct electrochemical use due to its easy desorption. To efficiently convert TREA-captured CO2 into C1 products, we optimized the system configuration based on the membrane electrode assembly (MEA) electrolyzer, and bipolar membrane applied MEA emerged as optimal. This system requires different mass transport approaches since the reactant is delivered in liquid phase, not as gaseous CO2. We developed a hydrophilic coral-Ag/carbon electrode that provides CO production active sites and facilitates interaction with TREA-captured CO2. This electrode achieved 70% CO Faradaic efficiency (FE) and 30% H2 FE at 20 mA cm-2, with selectivity varying by current density in the TREA-captured CO2 conversion system. Moreover, we discovered that high-purity syngas production is possible due to the re-capturing of unreacted CO2 in TREA, eliminating the need for post-production purification. Based on the experimental results and rigorous process modeling, we reveal that this system can produce high pressure syngas at a reasonable cost with negligible CO2 emissions.To enhance system feasibility, we also developed TREA-captured CO2 conversion to produce highly concentrated formic acid, which exists primarily as formate (HCOO-) in aqueous solutions. In conventional eCO2R systems, converting formate to formic acid involves energy- and cost-intensive steps, including acidification and purification to separate formic acid from electrolyte precursors. Our method directly converts TREA-captured CO2 to formate using a Sn-Cu alloy catalyst, simplifying the purification of formate to formic acid in two-steps. Protonated TREA chemically stabilizes formate through ionic interaction, allowing for the stabilization of highly concentrated formate in the TREA solution. The Sn-Cu alloy achieved maximum 60% of formate FE at 50 mA cm-2 with 28% of H2 FE and 14% of CO, with selectivity varying by current density. During long-term operation at a constant current density condition of 100 mA cm-2, the Sn-Cu alloy produced 2.6 M formate in the TREA-captured CO2 system, recording 94% conversion captured CO2. The purification process of formate into formic acid does not require high temperatures (not exceeding 150°C) or harsh chemicals by utilizing amine switching method, highlighting our system's environmental and practical benefits. These demonstrate the practical feasibility and minimal global warming impact of the TREA-captured CO2 conversion system, compared to other advanced Carbon Capture and Utilization strategies. Figure 1

Lithium Redox Behavior at Liquid Lithium-Lead Alloy Electrodes in Molten LiCl–KCl

IntroductionFusion energy is vital in a carbon-free society and stable energy supply. The advanced liquid blanket concepts allow high-efficiency (~50%) power generation by applying gas-turbine cycles. In particular, liquid Li17Pb83 (lithium-lead eutectic alloy) coolant enables higher-temperature (850~1000 ℃) heat applications, such as effective hydrogen and synthetic fuel production, and process heat for industrial uses. For realizing the Li17Pb83 blanket systems, molten salt electrochemistry technologies can be applied to lithium isotope enrichment, high-purity Li17Pb83 production, and online lithium replenishment for the lithium burn-up through neutron nuclear reaction: 6Li(n,t)4He, under the operation of a fusion reactor. These application developments need to obtain the chemical activity of lithium (a Li) and to clarify lithium redox behavior at liquid LixPb100-x electrodes; 0 < x ≤ 17 at.%. Previous studies investigated the a Li in liquid LixPb100-x [1,2], and lithium redox potential (E Li) was estimated according to the following Nernst equation: E Li =E Li 0+(RT/F)ln(a Li+ /a Li in alloy). Thus, this study aims to clarify the lithium oxidation/reduction behavior at the LixPb100-x electrodes.ExperimentalThe experimental apparatus was installed in a glove box under a purified argon gas atmosphere. The working electrodes were a coil-like Ni wire (φ: 0.5 mm, A: 1.0 cm2), liquid Pb (A: 0.28 cm2), and liquid LixPb100-x (x: 4.6 or 14.8, A: 0.28 cm2). The liquid Pb and LixPb100-x were stored in J-shaped glass tubes (made of borosilicate glass, φ: 8 mm, t: 1 mm). The molar ratio of the LixPb100-x was quantified by ICP-MS (Inductively Coupled Plasma-Mass Spectrometry). The quasi-reference electrode was a coil-like Mo wire (φ: 0.5 mm), and the redox potential was calibrated with Li+/Li standard potential. The counter electrode was a glassy carbon plate (t: 1 mm). The electrolytic bath was LiCl-KCl eutectic, and the bath temperature was controlled within ±2 ℃. Cyclic voltammetry and amperometry were performed at 500 ℃ to investigate the unsteady-state and steady-state polarization behaviors, respectively. In polarization measurements, the open circuit potential and chrono-amperometry were applied to adjust the lithium concentration of the LixPb100-x electrodes.Results and DiscussionFigure 1 shows cyclic voltammograms obtained at Ni, Pb, Li4.6Pb95.4, and Li14.8Pb85.2 electrodes at 500 ℃. Li+-ion was reduced and formed into lithium metal at 0.0 V on the surface of the Ni electrode. Nickel is significantly difficult to alloy with lithium[3], thus deposited lithium can be regarded as a pure substance: a Li = 1.0. Li+-ion was reduced and immediately dissolved in the liquid Pb, Li4.6Pb95.4, and Li14.8Pb85.2 electrodes. The relationship of E Li was summarized as follows: Ni < Li14.8Pb85.2 < Li4.6Pb95.4 < Pb. According to the Nernst equation, these results suggest that the relationship of a Li is estimated as follows: 0.0 < Pb < Li4.6Pb95.4 < Li14.8Pb85.2 < Ni = 1.0. The increasing tendency of a Li is in good agreement with the previous studies[1,2].Figure 2 shows steady-state polarization curves obtained at Li4.6Pb95.4 and Li14.8Pb85.2 electrodes at 500 ℃. In the case that the absolute value of overpotential (η) was large enough, current density (i) was an exponential of η in both electrodes. The polarization curves were fitted well with the following Tafel equations: η » 0, i ≃ i a = i0exp(αa Fη/RT), η « 0, i ≃ i c = i0exp(αc Fη/RT). These results suggest that a charge transfer is the rate-limiting step of lithium redox behavior at the LixPb100-x electrodes. The lithium redox behaviors at different temperatures will be presented at the meeting.

Structural and Electronic Modification of Electrocatalyst By Se Doping for Hydrogen Evolution Coupled Selective Electrooxidation of Ethylene Glycol to Glycolic Acid

Chemical reforming by electrochemical reaction has attracted great attention due to mild reaction condition and ease of control. As the raw materials for electrochemical reforming, ethylene glycol (EG) is advantageous for its large-scale production and cheap market price. Various organic acids such as glycolic acid (GCA), oxalic acid (OXA) and formic acid (FA) can be produced with simultaneous production of high purity of dihydrogen gas during ethylene glycol oxidation reaction (EGOR). In particular, EG selective oxidation targeted at the production of GCA, which has broad applications in skin care, textile industry and adhesives.Herein, a noble catalyst material of Pt nanoparticles supported on Se-doped porous carbon (Pt/SePC) is prepared and investigated for the selective EGOR to GCA. The Pt/SePC achieved a maximum EG conversion of 94.6% and GCA selectivity of 84.4%, and maintained this high performance with a negligible degradation during durability tests. The effect of Se doping was investigated through the experimental analyses and theoretical DFT calculations, that lattice deformation and defects introduction caused by Se led to electronic localization in Pt nanoparticle, thus the adsorption energy of intermediate reactants on Pt surface were modified. Furthermore, EGOR required low overpotential compared with oxygen evolution reaction, thus coupling EGOR and hydrogen evolution reaction required potential of 0.60 V while 1.58 V is necessary for water electrolysis. Our study could highlight favorable strategy of catalyst design with heteroatom doping for catalyst stabilization and promoting ethylene glycol conversion to value-added glycolic acid.