Amino Acid Salt Research Articles

Investigation on vapour–liquid equilibrium (VLE) solubility of CO2 in aqueous solutions of amino sugars

AbstractAmino sugars, which are candidate CO2‐capturing solvents, react reversibly with CO2, thereby setting up vapour–liquid equilibrium (VLE). Knowing equilibrium data is useful for designing gas–liquid contactors for CO2 absorption. In this work, VLE data for two amino sugars, glucosamine (GA) and N‐methyl‐D‐glucamine (NMG), was measured and reported at 303, 308, and 313 K using a high‐pressure VLE setup for the first time. The equilibrium CO2 partial pressure was high (up to 1500 kPa). The molarity of sugar in the aqueous solution was in the 0.5–1.25 M range. It was found that the CO2 loading capacity of NMG was much higher than that of GA. For instance, 1.25 M NMG loaded 1.066 mol/mol at 303 K and 1500 kPa CO2 partial pressure. Using regression, empirical equations were developed to predict VLE data for GA and NMG. To enable comparison, VLE trials were also performed using two amines, monoethanolamine (MEA) and 2‐amino‐2‐methyl‐1‐propanol (AMP), and an amino acid salt potassium glycinate (PG). It was found that CO2 solubility (α, mol/mol) in NMG was comparable to that in MEA and higher than that in PG. Besides, it was also found that CO2 was most soluble in AMP. The effect of promoter addition on the loading capacity at T = 308 K was studied too. The value of CO2 solubility in GA solution (1 M) at = 1450 kPa was α = 0.298 mol CO2/mol amino sugar. It improved to α = 0.46 mol/mol in GA/NMG (1/0.5 M) mixtures. Similarly, the CO2 solubility in NMG solution (0.75 M) at = 250 kPa was α = 0.76 mol CO2/mol amino sugar. It improved to 0.94 and 0.93 mol/mol in NMG/PZ and NMG/AMP (0.75/0.25 M) mixtures (here, PZ denotes piperazine). In this way, this work provided new and useful VLE data for individual and blended sugar solutions.

Rapid carbonate precipitation induced by carbamate coating: A new approach to form impermeable thin barrier and its mechanism

Various coating strategies have been explored in the past to prevent the ingress of aggressive substances into concrete. However, either the durability or performance is still far from satisfaction. Here, carbamate solutions were prepared by pre-absorbing CO2 into amino acid salts (AASs) to carbonize the surface of cementitious materials. The high concentration of carbonate ions provided by the carbamate induced rapid surface carbonation, resulting in the formation of an AAS-CaCO3 composite barrier with a thickness of 2–3 μm and possessing high micromechanical properties. Additionally, it was observed that the barrier's effectiveness depends on the molecular structures of the amino acids employed. Coatings formed by arginine-based carbamates demonstrated excellent performances, likely due to the highly compacted calcite particles they produced. This easy-to-operate and effective strategy has the potential to open new avenues for the development of highly durable and impermeable coating barriers for practical applications.

Experimental investigation of CO2 capture at high pressure using energy-efficient amino acid salt solvents

The increase in energy consumption has led to greenhouse gas emissions, specifically CO2. This has caused many researchers to explore the possibility of capturing CO2 emissions. The utilization of typical water-based solvents, such as amine solutions, poses challenges in large-scale operations owing to the substantial energy consumption associated with their regeneration process. To decrease the energy required to regenerate the solvent, new types of phase change solvents, known as lean water amino acid-based phase change solvents, were invented. This study investigated the absorption capacity of an amino acid salt made up of glutamine and potassium hydroxide in a water-based solution including N,N-dimethylformamide (DMF) as a co-solvent. The measurement of absorption capacity was conducted under elevated pressures ranging from 5 to 30 bar. Additionally, an investigation was conducted to assess the impact of DMF volumetric concentration on absorption capacity. The findings of the study indicated that augmenting both the pressure and concentration of DMF increased the capacity for CO2 absorption. This enhancement was achieved by simultaneously raising the rates of physical and chemical absorption. The results obtained from the C NMR phase analysis revealed that the solid phase had carbon bonds that were related to the absorption of CO2, whilst the upper liquid phase did not contain any CO2. This phase might readily be recycled into the absorption process without the need for regeneration. The absorption capacity of this solvent was also assessed following three absorption-reduction cycles. The results indicated a decrease in absorption capacity by only 6.6 %.

Improved efficiency and stability of inverse perovskite solar cells via passivation cleaning

Amidst the global energy and environmental crisis, the quest for efficient solar energy utilization intensifies. Perovskite solar cells, with efficiencies over 26% and cost-effective production, are at the forefront of research. Yet, their stability remains a barrier to industrial application. This study introduces innovative strategies to enhance the stability of inverted perovskite solar cells. By bulk and surface passivation, defect density is reduced, followed by a "passivation cleaning" using Apacl amino acid salt and isopropyl alcohol to refine film surface quality. Employing X-ray diffraction (XRD), scanning electron microscope (SEM), and atomic force microscopy (AFM), we confirmed that this process effectively neutralizes surface defects and curbs non-radiative recombination, achieving 22.6% efficiency for perovskite solar cells with the composition Cs0.15FA0.85PbI3. Crucially, the stability of treated cells in long-term tests has been markedly enhanced, laying groundwork for industrial viability.

Reactive capture of CO2 via amino acid

Reactive capture of carbon dioxide (CO2) offers an electrified pathway to produce renewable carbon monoxide (CO), which can then be upgraded into long-chain hydrocarbons and fuels. Previous reactive capture systems relied on hydroxide- or amine-based capture solutions. However, selectivity for CO remains low (<50%) for hydroxide-based systems and conventional amines are prone to oxygen (O2) degradation. Here, we develop a reactive capture strategy using potassium glycinate (K-GLY), an amino acid salt (AAS) capture solution applicable to O2-rich CO2-lean conditions. By employing a single-atom catalyst, engineering the capture solution, and elevating the operating temperature and pressure, we increase the availability of dissolved in-situ CO2 and achieve CO production with 64% Faradaic efficiency (FE) at 50 mA cm−2. We report a measured CO energy efficiency (EE) of 31% and an energy intensity of 40 GJ tCO−1, exceeding the best hydroxide- and amine-based reactive capture reports. The feasibility of the full reactive capture process is demonstrated with both simulated flue gas and direct air input.

Investigation of CO2 Rapid Phase Change Absorbent System Based on Amino Acid Salts and Ether Solvents

Investigation of CO₂ Rapid Phase Change Absorbent System Based on Amino Acid Salts and Ether Solvents

Phosphoric acid salts of amino acids as a source of oligopeptides on the early Earth

Because of their unique proton-conductivity, chains of phosphoric acid molecules are excellent proton-transfer catalysts. Here we demonstrate that this property could have been exploited for the prebiotic synthesis of the first oligopeptide sequences on our planet. Our results suggest that drying highly diluted solutions containing amino acids (like glycine, histidine and arginine) and phosphates in comparable concentrations at elevated temperatures (ca. 80 °C) in an acidic environment could lead to the accumulation of amino acid:phosphoric acid crystalline salts. Subsequent heating of these materials at 100 °C for 1–3 days results in the formation of oligoglycines consisting of up to 24 monomeric units, while arginine and histidine form shorter oligomers (up to trimers) only. Overall, our results suggest that combining the catalytic effect of phosphate chains with the crystalline order present in amino acid:phosphoric acid salts represents a viable solution that could be utilized to generate the first oligopeptide sequences in a mild acidic hydrothermal field scenario. Further, we propose that crystallization could help overcoming cyclic oligomer formation that is a generally known bottleneck of prebiotic polymerization processes preventing further chain growth.

A study on degradation and CO2 capture performance of aqueous amino acid salts for direct air capture applications

AbstractWe have previously proposed amino acid salts solutions as potential absorption liquids for direct air capture (DAC) of CO2 from the atmosphere. However, little is known about their relevant CO2 solubilities, CO2 mass transfer rates, and susceptibility to oxidative and thermal degradation under conditions relevant to DAC. We report here on the overall solubility of CO2 and CO2 mass transfer rates into a series of amino acid salts solutions. Additionally, the robustness of various amino acid salt solutions to thermal and oxidative degradation has been assessed.CO2 absorption rates into the amino acid salts solutions were observed to be in the same order of magnitude as aqueous monoethanolamine (MEA), with sarcosinate and lysinate solutions providing the fastest and slowest CO2 mass transfer rates at 25°C, respectively. Degradation data revealed that all amino acid salt solutions investigated in this study displayed elevated rates of thermal degradation at both 120 and 150°C relative to MEA. The opposite trend was observed with respect to oxidative degradation where all amino acid salt solutions showed a greater resistance to oxidative degradation than that observed for MEA under the conditions investigated here. Considering the degradation, CO2 absorption capacity, and CO2 mass transfer rate data, we propose the potassium salts of proline and sarcosine as the most promising amino acid salts (of those considered here) for further evaluation in DAC processes. Overall, this study provides valuable insight into the suitability of various amino acid salt solutions as absorption liquid for DAC. © 2024 The Author(s). Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley &amp; Sons Ltd.

Investigation of carbon dioxide absorption performance in amine amino acid salts for upgrading biogas applications: Blended absorbents of piperazine and amino acid solutions

BackgroundThe increasing amount of CO2 in the atmosphere is a critical environmental issue, necessitating the development of efficient CO2 capture technologies. Amine amino acid solutions (AAAS) have demonstrated potential in improving CO2 absorption and desorption. This study explores the efficiency of various AAAS, including piperazine (PZ), glycine (Gly), lysine (Lys), sarcosine (Sar), and alanine (Ala), under specific experimental conditions. MethodologyThe CO2 absorption and desorption processes were investigated using AAAS under conditions of 45 % CO2 at 313.15 K and with pure N2 at 353.15 K, respectively. The findings obtained for CO2 loading, regeneration rate, CO2 desorption heat, and 13C nuclear magnetic resonance (NMR) are valuable for understanding their impacts on the design and improvement of energy efficiency CO2 capture techniques. Furthermore, the physicochemical properties of PZ + lysine solutions such as density, viscosity, and vapor pressure were also measured at equimolar concentration ranges such as 0.75 M, 1.0 M, 1.25 M, and 1.5 M at T = 303.15 K to 353.15 K and 0.1 MPa pressure. Significant findingsThe study revealed significant enhancements in CO2 absorption and desorption with the addition of AAAS compared to monoethanolamine (MEA) solutions. Notably, among all the solutions, the PZ + lysine solution exhibited the maximum CO2 cyclic capacity at 0.792 mol CO2/mol absorbent, and the lowest regeneration heat. These findings provide valuable insights into the design and improvement of energy-efficient CO2 capture techniques.

INVESTIGATION OF CARBON DIOXIDE ABSORPTION CAPACITY AND DISSOLUTION RATE WITH AMINO ACID SALT SOLUTIONS: SODIUM AND POTASSIUM GLYCINATE

Global warming is a major world problem and causes climate change. The primary cause of global warming is carbon dioxide (CO2) emissions. Ongoing studies are being conducted to mitigate the effects of this problem. Anthropogenic CO2 emissions occur by burning fossil fuels to generate power and heat. To combat this problem, CO2 must be captured from point emission sources or directly from air. The conventional method to remove CO2 at the point emission sources is post-combustion systems. In these systems, absorption process is generally used to diminish CO2 emission and capturing at the source. Current researches aim to find an efficient and alternative solution to absorption. In this work, sodium glycinate (NaGly) and potassium glycinate (KGly), which are amino acid salt solutions, were investigated for CO2 absorption. Amino acid salt solutions have shown similar absorption kinetics and capacities to amine-based solutions due to same functional group. These solutions are usually more stable to oxidative degradation and have low volatilities, higher surface tensions and the viscosities are very close to waters. Experiments were performed using a stirred cell system at ambient temperature (20°C) and atmospheric pressure (91 kPa), in Ankara, Türkiye. In experiments, sodium glycinate and potassium glycinate concentration was ranged between 0.1 and 1.5 M. The experiments were also repeated with sodium hydroxide and potassium hydroxide in the same concentration range for comparison. In addition, the amino acid salt solutions examined in this study were compared with alkaline solutions and glycine in terms of total CO2 absorption capacity and CO2 dissolution rate. As a result of the experiments, the potassium glycinate solutions gave approximately 1.4 times better results than the sodium glycinate solutions at the highest concentration. Also, functional groups were determined by FTIR analysis of pure and CO2-loaded potassium glycinate solution.

Partially Ionized Amino Acid Salt Enabling Spatially Vertical n‐Phase Distribution of Quasi‐2D Perovskite for Efficient Deep‐Blue Light‐Emitting Diodes

AbstractThe deep‐blue perovskite light‐emitting diodes (PeLEDs) are of essential and indispensable for the application in full‐gamut display. However, the deep blue emission required large bandgap in small n phase exhibits high surface activity that gives rise to the difficulty of n phase distribution control spatially and proportionally in quasi‐2D perovskite films. Here, the deep‐blue pure‐bromide perovskite films is present that exhibit spatially vertical n phase distribution, owing to the partially ionized amino acid salt of 3‐Ammonium propionic acid bromide (3CBr) modulated crystallization kinetic of perovskite. The strong interaction of 3CBr and perovskite lattice improves the stability of small n phases, showing tunable photoluminescence (PL) emission and enhanced PL quantum yield (PLQY). The achieved champion deep blue PeLED shows a maximum EQE of 3.64% at electroluminescence (EL) emission wavelength of 466 nm, locating at the top rank of the similar devices. This work provides an effective strategy to fabricating efficient deep‐blue perovskite films and devices, promoting the development of perovskite‐based application in display.

Experimental study of hollow fiber membrane contactor process using aqueous amino acid salt-based absorbents for efficient CO2 capture

Gas–liquid membrane contactors are a promising alternative to packed columns that suffer from channeling, bubble formation, and flooding problems. In this study, potassium serinate + piperazine (PSZ) and potassium alaninate + piperazine (PAZ), which are amino acid salts with good CO2 absorption performances and high surface tensions, are investigated to determine the effects of the operating parameters on the CO2 removal efficiency, CO2 absorption flux, CO2 loading, and overall mass-transfer coefficient in the membrane contactor process. The experimental results demonstrate that the 2.5 M PSZ and 2.5 M PAZ absorbents outperform 2.5 M monoethanolamine (MEA) under various operating conditions, including the gas flow rate, liquid flow rate, CO2 concentration, and CO2-loaded absorbent. Based on these results, an expression for predicting the CO2 loading from the pH is proposed. The amount of cross-over confirmed that amino acids with high surface tension have better resistance to membrane wetting than 2.5 M MEA. In addition, empirical correlation expressions were established from the results of several operating parameters. The absolute average deviation (AAD) values were 6.50 %, 2.95 %, and 4.71 % for 2.5 M MEA, 2.5 M PSZ, and 2.5 M PAZ, respectively, suggesting good agreement between the theoretical and experimental results.

Carrier-driving CO2 separation by amine-rich membranes with intercalated graphene oxide

Amine-rich facilitated transport membranes (FTMs) attract great interest in intensifying the membrane-based CO2 separation processes. The high-molecular-weight polyvinylamine (PVAm) polymers containing fixed-site carriers of the amino groups were used to prepare highly CO2-permeable membranes. The sterically hindered PVAm polymers of poly(N-methyl-N-vinylamine) and poly(N-isopropyl-N-vinylamine) were obtained by functionalization of PVAm to provide superior CO2 solubility. By loading the mobile carriers of amino acid salt (AAS) and CO2-philic graphene oxide (GO), the prepared FTMs render enhanced CO2 permeance and CO2/N2 selectivity. The d-spacing of 8.8 Å and the ultramicropores of 3.5 Å from GO nanosheets provide the combination of both selective surface flow and molecular sieving mechanisms to achieve improved CO2 permeance and CO2/N2 selectivity. In addition, the intercalation of GO hinders N2 transport through the membrane due to a longer pathway, while the mobile carriers of AAS introduced into the PVAm matrix facilitate CO2 transport through the selective layer. Therefore, the CO2/N2 selectivity of the prepared FTMs was significantly enhanced to 171 based on the intensified carrier-driving transport mechanism. It can be concluded that amine-rich membranes based on both fixed and mobile carriers of the amino groups together with intercalated GO can synergistically improve the CO2/N2 separation performance, and be potentially applied for CO2 capture from flue gas.

Interface engineering for highly efficient carbon-based all-inorganic perovskite solar cells using functionalized amino acid salts

Interface engineering for highly efficient carbon-based all-inorganic perovskite solar cells using functionalized amino acid salts

Insight into CO2 capture by aqueous solutions of N,N‐diethylethanolamine promoted with potassium salts of amino acids

AbstractN,N‐Diethylethanolamine (DEEA) is a potential high‐capacity CO2‐capturing solvent. The CO2 reactivity of DEEA can be improved by the addition of rate promoters. Both equilibrium CO2 solubility and desorption rate are also influenced by promoters. In this work, the effect of promotion of DEEA with three amino acid salts, potassium arginate (PA), potassium prolinate (PP), and potassium glycinate (PG), was investigated. In a stirred cell reactor, CO2 reactivity of the promoted solutions was studied at 303 K. Rate promotion with PA was most effective; this was then followed by PP and PG. The value of the liquid‐side mass transfer coefficient (0.005 cm/s) for CO2 absorption in water inside the stirred cell was found. Equilibrium CO2 solubility in the promoted mixtures was measured. Empirical equations that predicted solubility data (accuracy 99%) were proposed. Desorption trials were performed at 363 K. PA, PP, and PG lowered sensible energy constraint by 59%, 32%, and 30%. PA was most‐suited for faster desorption of aqueous solutions of DEEA. Overall, potassium salts of arginine, proline, and glycine were promising candidates for improving the performance of the tertiary amine DEEA. Finally, catalytic desorption of loaded solutions of DEEA was studied and it was found that alumina was a promising catalyst for faster desorption.

Research progress of small molecule carbon dioxide capture agent

At present, the excessive emission of carbon dioxide has threatened people 's living environment and future development. More and more countries have begun to pay attention to carbon emission reduction. China has set the dual-carbon strategic goal of “carbon dioxide content reaches its peak” and “carbon neutrality”. According to the research on carbon dioxide capture technology by many scholars at home and abroad, it is found that the use of chemical absorbents to capture carbon dioxide is a relatively low cost, less technical difficulty, and can be widely put into industrial production. In this paper, several common chemical absorbents such as hot potassium alkali method, organic amine absorption method, amino acid salt, ionic liquid and phase change absorbent are reviewed. Through the research of various kinds of absorbents by researchers from various countries, their reaction principle, performance advantages and disadvantages, research status are introduced, and the future development direction of carbon dioxide negative emission technology is analyzed.

Recognition of Amino Acid Salts by Temperature-Dependent Allosteric Binding with Stereodynamic Urea Receptors.

Positive homotropic artificial allosteric systems are important for the regulation of cooperativity, selectivity and nonlinear amplification. Stereodynamic homotropic allosteric receptors can transmit and amplify induced chirality by the first ligand binding to axial chirality between two chromophores. We herein report stereodynamic allosteric urea receptors consisting of a rotational shaft as the axial chirality unit, terphenyl units as structural transmission sites and four urea units as binding sites. NMR titration experiments revealed that the receptor can bind two carboxylate guests in a positive homotropic allosteric manner attributed to the inactivation by intramolecular hydrogen-bonding between urea units within the receptor. In addition, the VT-CD spectra observed upon binding of the urea receptor with l- or D-amino acid salts in MeCN showed interesting temperature-dependent Cotton effects, based on the differences of the receptor shaft unit and the guest structure. The successful discrimination of hydrocarbon-based side chains of amino acid salts indicated that the input of chiral and steric information for the guest was amplified as outputs of the Cotton effect and the temperature-dependence of VT-CD spectra through cooperativity of positive allosteric binding.

Deep eutectic solvents formed by novel metal-based amino acid salt and dihydric alcohol for highly efficient capture of CO2

Deep eutectic solvents (DESs) are considered to be potential absorbents for CO2 capture compared to traditional amine solutions, because they have many advantages such as lower volatility and better thermal stability. In this study, a series of novel γ− and ε− m−based amino acid salts (AASs) were prepared through one-step hydrolysis reaction of accessible and cheap lactams as hydrogen bond acceptor (HBA). The chemical structures of these AASs were characterized by ESI-MS and NMR. Dihydric alcohol was selected as hydrogen bond donor (HBD) to prepare AAS-based DESs because of its low specific heat capacity and high boiling point. The physical properties of AAS-based DESs, such as density at 313.2–353.2 K, viscosity at 313.2–353.2 K, the melting temperature from 173.2 to 273.2 K, and thermal decomposition temperature from 300 to 750 K, were also determined. The gas absorption experiments were carried out on a dual-chamber at temperatures from 313.2 to 333.2 K and pressures up to 1.1 bar. It is found that K[Gaba]-EG has the largest CO2 uptake capacity with 0.12 g·g−1 at 1.0 bar and 313.2 K, better than almost all absorbent with AASs reported in literatures (0.02 g·g−1 ∼ 0.07 g·g−1). The CO2 absorption mechanisms were proved to be a combination of 2:1 and 1:1 stoichiometric reaction through thermomechanical analysis and NMR. This paper will present distinctive insights into the preparation of CO2 absorbent for effective carbon capture.

Cadmium induced changes in rhizosphere microecology to enhance Cd intake by Ligusticum sinense cv. Chuanxiong

As the most famous and widely used traditional Chinese medicine (TCM), Ligusticum sinense cv. Chuanxiong (L. Chuaniong) has been affected by cadmium (Cd) exceeding with high ability of Cd accumulation. There is relatively little research on Cd absorption and storage process in L. Chuanxiong, which is an important reason for the poor remediation efficiency. Hence, this study takes L. Chuanxiong as the point of penetration to explore how L. Chuanxiong affects rhizobacteria through root exudates to alter soil Cd intake, as well as to explore the migration and storage of Cd in its body with 0.10 (T0), 5.00 (T5), 10.00 (T10) mg/kg Cd contaminations. The results showed that the relative abundance of amino acids and phospholipids secreted from L. Chuanxiong root noticeably increased with increasing Cd levels, which directly activated soil Cd or extremely significantly (P < 0.01) recruited bacteria such as Bacillus, Arthrobacter to indirectly increase Cd availability. Under the interaction of root exudates and rhizobacteria, Cd bioavailability increased by 80.00% in rhizosphere soil and Cd accumulation in L. Chuanxiong increased 5.44–6.65 mg/kg. Cd subcellular distribution analysis demonstrated that Cd was mainly stored in the root (10-fold more than in the leaf), whose Cd content was cytoderm>cytoplasm>organelle in tissues. The sequential extraction results found that non-soluble phosphate and protein-chelated Cd dominated (85.00–90.00%) in the cell, while Cd cheated with alcohol soluble protein, amino acid salts, water-soluble organic acid in cell was minimal (5.50%). The phenomenon indicated that L. Chuanxiong fixed Cd in root (the medical part) with low translocation ability. This study can provide theoretical support for the high-quality production of L. Chuanxiong and other root medical plant in heavy metal influenced sites.

Selectivity in Catalytic Asymmetric Formal [3 + 3] Annulation of 2-Enoyl-pyridine N-Oxide with Benzyl Methyl Ketone

The asymmetric formal [3 + 3] annulation process of (E)-2-(3-phenylacryloyl)pyridine N-oxide with benzyl methyl ketone was investigated. The possibility of a stereoselective outcome was checked using salts of natural amino acids, as well as chiral bifunctional derivatives containing amino groups and thiourea or squaramide fragments as organocatalysts. Different types of organocatalysts applied led to opposite enantiomers of 2-(3-oxo-4,5-diphenyl-cyclohex-1-en-yl)pyridine 1-oxide (up to 60% ee). Spectroscopic analysis of the isolated product and analysis of the reaction course was carried out, taking into account the obtained regio- and stereoselectivity. In order to verify the postulated results, calculations of the energy of the intermediate reaction products and the final product using the Kohn–Sham Density Functional Theory (KS-DFT) were made.