Low Vapor Pressure Research Articles

Recovery and Reuse of Acetone from Pharmaceutical Industry Waste by Solar Distillation

Solvents are particularly hazardous among the mixture of pollutants found in the air, as their low vapor pressure allows them to reach the atmosphere, causing damage to ecosystems, and producing secondary deleterious effects on living organisms through a wide variety of possible reactions. In response, innovative, sustainable, and ecological methods are being developed to recover solvents from industrial wastewater, which is typically contaminated with other organic compounds. This study describes the procedure for recovering acetone from a residue from the pharmaceutical industry. This compound contains a high amount of solid organic compounds, which are generated during the manufacture of medicines. The treatment consisted of performing a simple solar distillation using a single-slope glass solar still, which separated the acetone from the mother solution. Under ideal circumstances, the use of solar radiation allowed an efficiency rate of 80% using solar concentration by means of mirrors to increase the temperature and 85% without the use of mirrors in the production of distilled acetone, which was characterized to evaluate its quality using instrumental analytical techniques: NMR, IR, and GC. The results obtained indicate that the acetone recovered by this procedure has a good quality of 84%; however, due to this percentage obtained, its reuse is limited for certain applications where a high degree of purity is required, such as its reuse for pharmaceutical use; for this reason, it was proposed to use said compound to eliminate the organic impurities contained in the catalyst waste granules used in a Mexican oil refinery. The resulting material was examined by SEM and EDS, revealing a high initial carbon content that decreased by 29% after treatment. Likewise, as an additional study, a study was carried out to evaluate the characteristics of the residues obtained at the end of the distillation where rubidium, silicon, carbon, nitrogen, oxygen, and chlorine contents were observed.

Effects of Different Ionic Liquids on Microbial Growth and Microbial Communities' Structure of Soil.

Ionic liquids (ILs) are widely used "green solvent" as they have a low vapor pressure and can replace volatile solvents in industry. However, ILs are difficult to biodegrade and are potentially harmful to the environment. This study, herein, investigated the toxicity of three imidazole ILs ([C8MIM]Cl, [C8MIM]Br, and [C8DMIM]Br) towards soil microorganisms. The results showed that the ILs inhibited the growth of soil culturable microorganisms and affected the activity of soil enzyme. In addition, microbial communities' species and abundance in soil were altered. Finally, functional prediction analysis revealed that ILs mainly affected the carbohydrate metabolism and amino acid metabolic processes of the microorganisms. ILs with single methyl substituent had a more pronounced effect than those with double methyl substituents. The study indicates that the use of ILs with double methyl substituents is more environmentally safe, and that the toxicity of ILs should be taken into account in industrial production for the design and production of more environmentally safe types, such as ILs with double methyl substituents.

Supramolecular Ionic Gels for Stretchable Electronics and Future Directions.

Ionic gels (IGs), ionic liquids (ILs) dispersed in polymers, exhibit extremely low vapor pressure, electrochemical and thermal stability, and excellent mechanical characteristics; therefore, they are used for fabricating stretchable sensors, electrochemical transistors, and energy storage devices. Although such characteristics are promising for flexible and stretchable electronics, the mechanical stress-induced ruptured covalent bonds forming polymer networks cannot recover owing to the irreversible interaction between the bonds. Physical cross-linking via noncovalent bonds enables the interaction of polymers and ILs to form supramolecular IGs (SIGs), which exhibit favorable characteristics for wearable devices that conventional IGs with noncovalent bonds cannot achieve. Herein, we review recent material designs and interactions used for fabricating SIGs, such as ionic interactions and hydrogen bonding. We present SIG characteristics achieved via the interaction of polymers and ILs, such as extreme toughness, self-healing capability, and self-adhesion favorable for human body sensors. We conclude this Perspective by discussing the potential of SIGs as a power source for implants, wearable devices, and environmental sensing applications.

Recovery of iron as hematite and separation of trivalent lanthanide ions from spent hard disk magnet leach liquor using [P66614][Cy272] ionic liquid.

The widespread use of neodymium-iron-boron (NdFeB) magnets has raised concerns about the environmental impact of their disposal, prompting the need for sustainable recycling strategies. Traditional solvents used in recycling are toxic and flammable, making them risky to use. Ionic liquids are safer and greener options with low vapor pressure, high stability, and less flammability. This study introduces an eco-friendly recycling approach utilizing the [P66614][Cy272] ionic liquid to selectively extract iron and recover rare earth elements (REEs) from the leach liquor of waste NdFeB magnets. Pre-treatment processes enhanced metal concentration before leaching, including demagnetization, grinding, and screening. Optimal leaching conditions: 2 mol L-1 HCl, 80 °C, 10 g L-1 pulp density, and 90 minutes, resulted in complete leaching of REEs (Dy, Pr, Nd), iron, and boron. Using 0.01 mol L-1 [P66614][Cy272] ionic liquid, 100% of the iron was removed from the leach liquor with minimal co-extraction of REEs (∼4%). Precipitation of iron leading to Fe2O3 (hematite) after calcination and is verified through XRD and SEM-EDS analyses. The ionic liquid also enabled 81.1% recovery of HCl from the leach liquor, reducing neutralization needs and operational costs. Subsequent REEs separation using 0.01 mol L-1 [P66614][Cy272] ionic liquid demonstrated high selectivity, achieving separation factors of 18.55 (Dy/Pr) and 15.52 (Dy/Nd) at pH 2.03. Dy(iii) was successfully separated from NdFeB leach solutions using counter-current extraction, leaving 6.0 mg L-1 in the raffinate, requiring two extraction stages at a 2 : 3 organic-to-aqueous phase (O/A) ratio. The reusability of the ionic liquid further enabled a sustainable, closed-loop recycling process. This approach highlights the potential for integrating ionic liquids into green technologies for NdFeB magnet recycling, ensuring resource recovery while minimizing environmental impact.

An improved endwall-injection technique for examining high-temperature ignition of lubricating oils in shock tubes.

Ignition of the lubricating fluid in a mechanical system is a highly undesirable and unsafe condition that can arise from the elevated temperatures and pressures to which the lubricant is subjected. It is therefore important to understand the fundamental chemistry behind its ignition to predict and prevent this condition. Lubricating oils, particularly those with a mineral oil base, are very complex mixtures of thousands of hydrocarbons. Additionally, these oils have very low vapor pressures and high viscosities. These physical characteristics present considerable barriers to examining and understanding lubricant ignition chemistry. Therefore, a novel experimental design was devised to create and introduce a lubricant aerosol into a shock-tube facility in a reliable yet relatively simple manner. In this way, the lubricant can be quasi-homogeneously introduced into the shock tube where it will be vaporized by the incident shock wave, and combustion can be observed behind the reflected shock wave. To characterize the technique and anchor it with previously established methods, n-hexadecane was chosen to be tested both with the endwall injection and the well-established, heated shock tube techniques. This comparison showed good agreement, proving the ability of the simple technique to produce reliable ignition delay time (IDT) results. From here, Jet-A was also tested with the current injection technique and compared to a previous generation of the technique to highlight the advantages of the present method. Then, IDT results for mineral oil were collected to establish a baseline IDT set to which off-the-shelf lubricants and additional mixtures can be compared. Finally, IDTs for the off-the-shelf, mineral-based lubricant Mobil DTE 732 were obtained and compared to the baseline as well as the n-hexadecane results. All experiments were conducted near atmospheric pressure and for temperatures between 1084 and 1530K. An analysis of the system estimated the effective stoichiometry to be around ϕ = 1.15. Although no kinetics mechanisms exist for lubrication oils, preliminary model predictions made by modern chemical kinetics mechanisms for an alkane with 16 carbon atoms were then compared to the results to elucidate some of the chemistry this new method will allow the community to probe. This paper establishes the new method as a viable way to study and compare the ignition behavior of lubricating oils and other very low-vapor-pressure fuels in a shock tube.

Recent Advancement in the Development of Detection and Removal of Heavy Metal Ions by Deep Eutectic Solvents: A Review

: Heavy metal pollution is one of the most serious environmental problems, because of the non-degradable nature of heavy metals and their accumulation in the food chain, which poses a severe threat to the environment and human health even at low concentrations. Most of these metal ions can coordinate with biological molecules and disturb their function. Exposure to heavy metals can cause different health threats such as endothelial dysfunction, allergy, infant mortality, cancer, neurological diseases, respiratory diseases, oxidative stress, cardiovascular disorders and kidney diseases. Therefore the detection and removal of these toxic species are very important. Deep eutectic solvents (DESs) are green solvents and have excellent applications in many fields. They contain nonsymmetrical ions that have low lattice energy, low vapor pressure, dipolar nature, nonflammability, low volatility, low melting points, excellent thermal and chemical stability and high solubility. DESs are also better in terms of the availability of raw materials, easy synthetic procedure, low cost of their starting materials and their easy storage. DESs have an excellent ability for the detection and removal of heavy metal ions. In this review, we discussed various DES-based spectrophotometric and fluorimetric chemosensors for the detection of heavy metal ions in different matrixes. Additionally, we have also explored the capabilities of different DESs in removing heavy metals.

State-of-the-art advances in homogeneous molecular catalysis for the Guerbet upgrading of bio-ethanol to fuel-grade bio-butanol.

The upgrading of ethanol to n-butanol marks a major breakthrough in the field of biofuel technology, offering the advantages of compatibility with existing infrastructure while simultaneously offering potential benefits in terms of transport efficiency and energy density. With its lower vapour pressure and reduced corrosiveness compared to ethanol, n-butanol is easier not only to manage but also to transport, eliminating the need for costly infrastructure changes. This leads to improved fuel efficiency and reduced fuel consumption. These features position n-butanol as a promising alternative to ethanol in the future of biodiesel. This review article delves into the cutting-edge advancements in upgrading ethanol to butanol, highlighting the critical importance of this transformation in enhancing the value and practical application of biofuels. While traditional methods for making butanol rely heavily on fossil fuels, those that employ ethanol as a starting material are dominated by heterogeneous catalysis, which is limited by the requirement of high temperatures and a lack of selectivity. Homogeneous catalysts have been pivotal in enhancing the efficiency and selectivity of this conversion, owing to their unique mode of operation at the molecular level. A comprehensive review of the various homogeneous catalytic processes employed in the transformation of feedstock-agnostic bio-ethanol to fuel-grade bio-n-butanol is provided here, with a major focus on the key advancements in catalyst design, reaction conditions and mechanisms that have significantly improved the efficiency and selectivity of these Guerbet reactions.

Kinetics, thermodynamics, and catalysis of the cation incorporation into GeO2, SnO2, and (SnxGe1−x)O2 during suboxide molecular beam epitaxy

Rutile GeO2 is a promising ultra-wide bandgap semiconductor for future power electronic devices whose alloy with the wide bandgap semiconductor rutile-SnO2 enables bandgap engineering and the formation of heterostructure devices. The (SnxGe1−x)O2 alloy system is in its infancy, and molecular beam epitaxy (MBE) is a well-suited technique for its thin-film growth, yet it presents challenges in controlling the alloy composition and growth rate. To understand and mitigate this challenge, the present study comprehensively investigates the kinetics and thermodynamics of suboxide incorporation into GeO2, SnO2, and (SnxGe1−x)O2 during suboxide MBE (S-MBE), the latest development in oxide MBE using suboxide sources. We find S-MBE to simplify the growth kinetics, offering better control over growth rates than conventional MBE but without supporting cation-driven oxide layer etching. During binary growth, SnO incorporation is kinetically favored due to its higher oxidation efficiency and lower vapor pressure (limiting its loss by desorption) compared to those of GeO. In (SnxGe1−x)O2 growth, however, the GeO incorporation is preferred and the SnO incorporation is suppressed, indicating a catalytic effect, where SnO promotes GeO incorporation. The origin of this catalytic effect cannot be understood by comparing the binary kinetics or thermodynamics (cation–oxygen bond strengths), thus calling for further theoretical studies. Our experimental study provides guidance for controlling the growth rate and alloy composition of (SnxGe1−x)O2 in S-MBE, highlighting the impact of the substrate temperature and active oxygen flux besides that of the mere SnO:GeO flux stoichiometry. The results are likely transferable to further physical and chemical vapor deposition methods, such as conventional and hybrid MBE, pulsed laser deposition, mist-, or metalorganic chemical vapor deposition.

Removal of phenol from water using fenchol-menthol hydrophobic deep eutectic solvent

Hydrophobic deep eutectic solvents (HDESs) are regarded as a potential green alternative to conventional organic solvents in separation processes such as liquid-liquid extraction, due to their favourable properties, such as lower vapour pressure and tunable properties. The present work investigated the application of HDES which is synthesised from fenchol and menthol, in the removal of phenol from water. The HDES was synthesised experimentally at a fenchol mole fraction range of 0.1 to 0.9. The experimental results showed that stable liquidus HDES was successfully formed when the fenchol mole fraction in the HDES was 0.2 – 0.9. Further investigation showed that HDES with a fenchol mole fraction of 0.2, which had a low viscosity and high stability in water, had the highest phenol removal efficiency. The phenol removal process was highly sensitive to solution pH and solution-to-HDES ratio. In contrast, phenol removal was less affected by initial concentration and temperature. A high phenol removal efficiency of up to 95.9% was achieved in this study, which further showed the positive feasibility of HDES to serve as an alternative to conventional organic solvents in the liquid-liquid extraction of phenol from water.

Preparation and Characterization of Novel Core-Shell Microcapsules Containing C6F12O for Initial Fire Suppression

As an environmentally friendly and efficient fire extinguishing agent, C6F12O (CFO) is widely used for various types of fires. However, due to its low vaporization temperature and high vapor pressure, it is difficult to store and utilize. In order to reduce the loss and improve fire suppression efficiency of CFO, the complex coacervation method was employed to encapsulate CFO using a polymer material shell composed of gelatin (GE) and arabic gum (GA). The experimental results demonstrated that the preparation parameters had a significant impact on the microcapsule encapsulation efficiency. When the coacervation temperature was set to 40°C, the coacervation pH value was maintained at 3.8, the shell material concentration was adjusted to 8%, and the core-shell mass ratio was kept at 4:1, the microcapsule encapsulation efficiency reached its peak at 26.4%. CFO was successfully encapsulated as confirmed by characterization techniques such as TG, FT-IR, SEM, and 19F-NMR. CFO was released by breaking through the shell when the microcapsules reached the thermal response temperature. Additionally, the fire suppression tests showed that the microcapsules exhibited highly efficient fire extinguishing performance. They decreased the maximum temperature of the n-heptane flame by 196.7°C, lowered the temperature rate by 4.07°C/s, and shortened the self-extinguishing time by 47s. These results provide a new and effective solution for the microencapsulation of heat-sensitive materials and early-stage fire suppression.

A tough and high adhesive ionogel electrolyte achieved by in-situ phase separation for high-performance electrochromic devices

Ionogels are promising candidates for electrolytes used in electrochromic devices(ECDs) attributed to their good thermal stability, low saturation vapour pressure and high ionic conductivity. However, the poor mechanical and adhesive...

Deeply revealing the deactivation and decomposition mechanism of ammonium bisulfate on nanotube structured SCR catalysts for the low-temperature NH3-SCR reaction

The nanotube structure led to the strong interactions between the metals and improved the catalytic activity of the Ce–Mn-TNTs catalyst, and the lower vapor pressure inside the nanotube channels promoted the rapid decomposition of ABS.

Microplasma Controlled Nanogold Sensor for SERS of Aliphatic and Aromatic Explosives with PCA-KNN Recognition.

Nanogold is an emerging material for enhancing surface-enhanced Raman scattering (SERS), which enables the detection of hazardous analytes at trace levels. This study presents a simple, single-step plasma synthesis method to control the size and yield of Au nanoparticles by using plasma-liquid redox chemistry. The pin-based argon plasma reduces the Au3+ precursor in under 5 min, synthesizing Au spherical particles ranging from ∼20 nm at 0.025 mM to ∼90 nm at 1.0 mM, in addition to plate-like particles occurring at concentrations of 0.25-1.0 mM. The enhanced SERS responses correlated with the UV-vis absorption and reflectance profiles, which can be attributed to synergistic plasmonic hotspots created by the sphere-sphere, plate-sphere, and plate-plate nanogold interactions. This nanogold mixture, combined with gold-plated CPU grid pin arrays, facilitated the detection of trace explosives, including aromatic (TNT, TNB, and TNP) and aliphatic (RDX, PETN, and HMX) compounds. We demonstrate that stabler aliphatic analytes, associated with lower vapor pressure (10-8-10-11 atm), exhibit smaller signal fluctuations (RSD ∼ 6-10%) compared to their more volatile (10-5 atm) aromatic (RSD ∼ 12-17%) counterparts at similar analyte concentrations. The calculated limit of detection (LoD) was found to be ∼2-6 nM and ∼600-900 pM for aromatic and aliphatic explosives, respectively. Finally, we show that the poorer performance of aromatic explosives under the same sensing conditions affects SERS-PCA separation, which can then be improved either by a machine learning approach (PCA with k-NN classification) or by consideration of a specific NO2 symmetric stretching fingerprint range.

The elusive nature of Martian liquid brines

The possible presence of brines on Mars adds an intriguing dimension to the exploration of Martian environments. Their potential involvement in the formation of recurring slope lineae has sparked debates on the existence of liquid water versus alternative dry processes. In situ instrumentation on rovers and landers has been instrumental in providing valuable data for comprehending the dynamics of brines. Laboratory experiments and thermodynamic simulations conducted under Martian conditions offer insights into the formation and persistence of brines, shedding light on the planet’s current hydrological processes. Despite these findings, the prevailing surface conditions on Mars, characterized by a combination of low temperature, pressure, and water vapor pressure, generally hinder the stability of most brines. In such environments, only a few select salts, notably calcium perchlorate, could play a pivotal role in potentially forming brines through deliquescence or melting. These environmental factors emerge as critical contributors influencing the stability of brines, but such limitations generally restrict the locations, timescales, and amounts of brine formed. However, the exploration of brines extends beyond geochemical considerations, serving as a lens through which we can examine potential habitability and gain a broader understanding of the Martian climate. Therefore, observing brines on Mars would offer valuable insights into the dynamic interplay of various factors that influence their stability, contributing to our overall comprehension of Mars’ unique environmental conditions.

Responses of field-grown maize to different soil types, water regimes, and contrasting vapor pressure deficit

Abstract. Drought is a serious constraint on crop growth and production of important staple crops such as maize. Improved understanding of the responses of crops to drought can be incorporated into cropping system models to support crop breeding, varietal selection, and management decisions for minimizing negative impacts. We investigate the impacts of different soil types (stony and silty) and water regimes (irrigated and rainfed) on hydraulic linkages between soil and plant, as well as root : shoot growth characteristics. Our analysis is based on a comprehensive dataset measured along the soil–plant–atmosphere pathway at field scale in two growing seasons (2017 and 2018) with contrasting climatic conditions (low and high vapor pressure deficit). Roots were observed mostly in the topsoil (10–20 cm) of the stony soil, while more roots were found in the subsoil (60–80 cm) of the silty soil. The difference in root length was pronounced at silking and harvest between the soil types. Total root length was 2.5–6 times higher in the silty soil than in the stony soil with the same water treatment. At silking time, the ratios of root length to shoot biomass in the rainfed plot of the silty soil (F2P2) were 3 times higher than those in the irrigated silty soil (F2P3), while the ratio was similar for two water treatments in the stony soil. With the same water treatment, the ratios of root length to shoot biomass of silty soil were higher than for stony soil. The seasonally observed minimum leaf water potential (ψleaf) varied from around −1.5 MPa in the rainfed plot in 2017 to around −2.5 MPa in the same plot of the stony soil in 2018. In the rainfed plot, the minimum ψleaf in the stony soil was lower than in the silty soil from −2 to −1.5 MPa in 2017, respectively, while these were from −2.5 to −2 MPa in 2018, respectively. Leaf water potential, water potential gradients from soil to plant roots, plant hydraulic conductance (Ksoil_plant), stomatal conductance, transpiration, and photosynthesis were considerably modulated by the soil water content and the conductivity of the rhizosphere. When the stony soil and silt soil are compared, the higher “stress” due to the lower water availability in the stony soil resulted in fewer roots with a higher root tissue conductance in the soil with more stress. When comparing the rainfed with the irrigated plot in the silty soil, the higher stress in the rainfed soil resulted in more roots with a lower root tissue conductance in the treatment with more stress. This illustrates that the “response” to stress can be completely opposite depending on conditions or treatments that lead to the differences in stress that are compared. To respond to water deficit, maize had higher water uptake rate per unit root length and higher root segment conductance in the stony soil than in the silty soil, while the crop reduced transpired water via reduced aboveground plant size. Future improvements in soil–crop models in simulating gas exchange and crop growth should further emphasize the role of soil textures on stomatal function, dynamic root growth, and plant hydraulic system together with aboveground leaf area adjustments.

Long-Range Surface Forces in Salt-in-Ionic Liquids.

Ionic liquids (ILs) are a promising class of electrolytes with a unique combination of properties, such as extremely low vapor pressures and nonflammability. Doping ILs with alkali metal salts creates an electrolyte that is of interest for battery technology. These salt-in-ionic liquids (SiILs) are a class of superconcentrated, strongly correlated, and asymmetric electrolytes. Notably, the transference numbers of the alkali metal cations have been found to be negative. Here, we investigate Na-based SiILs with a surface force apparatus, X-ray scattering, and atomic force microscopy. We find evidence of confinement-induced structural changes, giving rise to long-range interactions. Force curves also reveal an electrolyte structure consistent with our predictions from theory and simulations. The long-range steric interactions in SiILs reflect the high aspect ratio of compressible aggregates at the interfaces rather than the purely electrostatic origin predicted by the classical electrolyte theory. This conclusion is supported by the reported anomalous negative transference numbers, which can be explained within the same aggregation framework. The interfacial nanostructure should impact the formation of the solid electrolyte interphase in SiILs.

“Low-Hanging Fruit” Practices for Improving Water Productivity of Rainfed Potatoes Using Integration of Cultivar Selection, Mulch Application, and Different Agroecological Zones in Sub-Tropical, Semi-Arid Regions

Unevenly distributed rainfall leads to reduced potato water productivity (WP) under rainfed production conditions. Understanding the practices that can increase WP is vital. Our objectives were to understand (i) the seasonal variables that influence WP under rainfed conditions and (ii) the effect of the integration of cultivar x locality x mulch on potato WP. The study was undertaken in smallholder settings in two agroecological zones: Appelsbosch (Mbalenhle locality) and Swayimane (Stezi and Mbhava locality). A split plot, in a randomized complete block design experiment, included mulching (mulch and no mulch), four selected cultivars, and s three localities. Soil water content (SWC), yield, and climatic data were collected, and actual crop evapotranspiration (ETa) and WP were calculated. Rainfall, ETa, and crop growth and development had a significant influence on the seasonal WP. Cultivar × mulch × locality had an insignificant effect on the WP, however, locality × cultivar significantly altered the WP. The localities that had lower vapor pressure deficit (VPD), high relative humidity, and sandy soil had a higher potato WP for all cultivars, with the highest (18.38 kg m−3) being that from Electra. The findings suggest that using localities that have less atmospheric dryness and a cultivar (Electra) that shows stability of yield across the seasons can be an easy-to-apply practice for increasing potato WP in a resource-limited environment.

The Chemistry of Atmospheric Aerosols: At the Nexus Between Climate, Energy, and Air Quality

Atmospheric aerosols can be emitted directly as particles or formed in the atmosphere from phase transitions of gaseous compounds with low enough vapor pressure. During their lifecycle in the atmosphere, aerosols undergo multiphase changes, altering chemical composition, reactivity, physical and optical properties, ultimately influencing how they impact climate, human health and ecosystems. The understanding of the chemical processes in the atmosphere is crucial to assess these effects. Here we provide a brief overview on relevant aerosol chemical processes and measurement techniques with no claim to completeness and describe the Swiss contribution to the European infrastructure ACTRIS for long-term monitoring and its relevance for the research field.

Application of liquid metal driven-abrasive flow to material removal for the inner surface of channel

Gallium-based eutectic liquid metal alloys possess unique properties such as deformability, high electrical conductivity, and low vapor pressure. These characteristics have generated significant interest in their application for stretchable electronics and microelectromechanical systems (MEMS). Precise manipulation of liquid metal within electrolytes is essential to meet specific functional requirements. This study investigates the electrostatic manipulation of liquid metal in an alkaline solution with abrasives for material removal from the inner surfaces of flow channels. The polarization of the double layer at the gallium‑indium alloy and electrolyte interface is analyzed, elucidating the principle of electrolyte propulsion via continuous electrowetting. A theoretical model is developed, and two- and three-dimensional transient and steady-state simulations of the liquid metal-driven abrasive flow are conducted. Results demonstrate that this method effectively removes material from the inner walls of straight channels during cyclic motion. Utilizing continuous electrowetting, an experimental apparatus was designed, where gallium‑indium liquid metal propelled silicon carbide abrasives against PMMA channel walls. Experimental results showed effective material removal, consistent with finite element simulations, confirming the feasibility of this innovative approach.

Reactive Capture of CO2 via Amino Acid

The electrochemical production of carbon monoxide (CO) from carbon dioxide (CO2) has conventionally relied on gas-phase CO2 electrolysis with complex upstream capture and downstream gas separation processes. Reactive capture of CO2 – an integrated approach that combines CO2 capture and electrochemical conversion – uses chemisorbed CO2 directly as the feedstock and thereby avoids CO2 purification and associated costs.To date, reactive capture has relied on hydroxide-based capture solutions (e.g. potassium hydroxide (KOH)) suitable for direct air capture (DAC) processes or amines (e.g. monoethanolamine (MEA)) that have been conventionally used for point source capture. However, in hydroxide-based systems that capture CO2 in the form of carbonate, the CO Faradaic efficiency (FE) is limited to 50% due to the interaction between in-situ regenerated CO2 and local hydroxides that reduce CO2 availability at the cathode. Amine-based reactive capture can overcome this selectivity challenge when CO2 is captured in the form of carbamate and bicarbonate; compared to carbonate, these forms of chemisorbed CO2 require less electron-coupled protons to regenerate in-situ CO2, and thus yield more CO2 at the cathode. However, conventional amines are volatile and have poor oxygen tolerance, rendering them inapplicable to oxygen-rich CO2-lean conditions.Here, we report amino acid salt (AAS)-based reactive capture of CO2 that exceeds the CO energy efficiency (EE) achieved in amine- and hydroxide- based systems. The AAS capture solution, potassium glycinate (K-GLY), contains amino functional groups for efficient CO2 capture while offering advantages including oxygen tolerance, low vapor pressure, and low toxicity. We synthesized a nickel single atom (Ni-N/C) catalyst to improve conversion efficiency, optimized the capture solution composition to reduce the electrolysis overpotential at high current densities, and elevated the operating temperature and pressure to increase availability of dissolved in-situ CO2 at the cathode. We achieve CO production with 64% CO FE and a measured full cell voltage of 2.74 V at 50 mA cm-2, resulting in an CO EE of 31% and an energy intensity of 40 GJ tCO-1. The feasibility of the full reactive capture process was demonstrated with both simulated flue gas and direct air input.