Dioxide In Aqueous Solutions Research Articles

Addressing the Effectiveness and Molecular Mechanism of the Catalytic CO2 Hydration in Aqueous Solutions by Nickel Nanoparticles.

Hydration of carbon dioxide in water solution is the rate limiting step for the CO2 mineralization process, a process which is at the base of many carbon capture and utilization (CCU) technologies aiming to convert carbon dioxide to added-value products and mitigate climate change. Here, we present a combined experimental and computational study to clarify the effectiveness and molecular mechanism by which nickel nanoparticles, NiNPs, may enhance CO2 hydration in aqueous solutions. Contrary to previous literature, our kinetic experiments recording changes of pHs, conductivity, and dissolved carbon dioxide in solution reveal a minimal effect of the NiNPs in catalyzing CO2 hydration. Our atomistic simulations indicate that the Ni metal surface can coordinate only a limited number of water molecules, leaving uncoordinated metal sites for the binding of carbon dioxide or other cations in solution. This deactivates the catalyst and limits the continuous re-formation of a hydroxyl-decorated surface, which was a key chemical step in the previously suggested Ni-catalyzed hydration mechanism of carbon dioxide in aqueous solutions. At our experimental conditions, which expand the investigation of NiNP applicability toward a wider range of scenarios for CCU, NiNPs show a limited catalytic effect on the rate of CO2 hydration. Our study also highlights the importance of the solvation regime: while Ni surfaces may accelerate carbon dioxide hydration in water restricted environments, it may not be the case in fully hydrated conditions.

Thermochemical Properties of Synthesized Urea from Recovered Ammonia and Carbon Dioxide in Well-Ordered Nanospaces of Hollow Silica Spheres.

The present work investigated the thermochemical properties of urea synthesized in well-ordered nanospaces of porous hollow silica spheres' shells from recovered ammonia and carbon dioxide in aqueous solution. Thermochemical behaviors of the urea synthesized in well-ordered nanospaces of the hollow spheres' shells prepared with 1-dodeclyamine were analyzed from the results of thermogravimetric analysis (TGA) and differential thermal analysis (DTA), and endothermic peaks assigned as the phase transition and decomposition were observed at ca. 440 and 514 K, respectively, which were higher than those of pristine urea (405 and 408 K, respectively), probably because of the nanoconfinement effect. The decomposition behavior was also confirmed by the result of diffuse reflectance infrared Fourier transform (DRIFT) spectra of the samples treated at various temperatures up to 573 K, and the decomposition of urea synthesized in the well-ordered nanospaces of the hollow spheres' shells started at 468 K and completed up to 533 K.

High-pressure solubility measurement and eNRTL thermodynamics modeling of carbon dioxide in aqueous solutions of 2-((2-aminoethyl) amino) ethanol + dimethyl sulfoxide at different conditions

We measured the solubility of carbon dioxide in the aqueous solution of 2-((2-aminoethyl) amino) ethanol (AEEA) as a chemical solvent plus dimethyl sulfoxide (DMSO) as a physical solvent. A quasi-static high-pressure equilibrium cell was used for the measurement of CO2 solubility in the AEEA + DMSO + H2O systems at the compositions of (10, 20, 70), (15, 15, 70), (20, 10, 70), (25, 5, 70) wt. %. We performed the experiments at temperatures of 318.15, 328.15, and 343.15 K and pressures up to 5000 kPa. Also, we compared the CO2 solubility in the aqueous mixture of 2-((2-aminoethyl) amino) ethanol (AEEA) + dimethyl sulfoxide (DMSO), 2-((2-aminoethyl) amino) ethanol (AEEA) + sulfolane, methyl diethanolamine (MDEA) + dimethyl sulfoxide (DMSO), and methyl diethanolamine (MDEA) + sulfolane. We used the Electrolyte-NRTL thermodynamic model to correlate the solubility of CO2 in the aqueous solutions of AEEA + DMSO and to predict the partial pressure of CO2 versus the acid gas loading. The present modeling provided an excellent representation of the experimental data over the whole temperature range for 121 experimental data, which resulted in an average absolute deviation of 12.96 %.

Performance of a high capacity polyamine: Measurement and modeling of the solubility of carbon dioxide in aqueous solutions of 1, 4-bis (3-amino-propyl) piperazine and its heat of absorption

This study focused on measuring the carbon dioxide (CO2) uptake capacity of an amine, 1, 4-Bis (3-aminopropyl) piperazine. The solubility of CO2 was measured at 313.15 K and 333.15 K for three amine concentrations (10, 20, and 30 wt%) of importance in industry and different CO2 partial pressures up to 2.4 MPa. CO2 loadings (mol of CO2/mol amine) were measured using the pressure decay method. At all concentrations, 1,4-Bis(3-aminopropyl) piperazine showed a higher CO2 loading compared to two benchmark amines namely, ethanolamine (MEA) and Piperazine (PZ). The proposed amine had also a higher capacity for CO2 than all other polyamines found in the literature, except, 3, 3 ’-Iminobis (N, N-dimethyl-propylamine) which has two tertiary and one secondary amino group. The experimental measurements were modeled comprehensively with the electrolyte–Non-Random Two Liquid (NRTL) model and the Redlich-Kwong (RK) equation of state (EOS) for the gas phase. The binary NRTL and molecule–ion pair parameters were regressed and reported. The overall percentage of the average absolute deviation (%AAD) between the experimental and estimated values for the temperature, pressure, and mole fractions were 0.12%, 0.07%, and 0.32%, respectively. Finally, the heats of absorption of CO2 in 1, 4-Bis (3-aminopropyl) piperazine were calculated using the Gibbs-Helmholtz equation based on the obtained experimental solubility data. The modeling results for MEA, DEA, and MDEA between the elec-NRTL and the soft-SAFT models were compared. The estimation of the heat of absorptions for the amines was almost the same.

Relationship between the major parameters of warm-blooded organisms' life activity and the properties of aqueous salt solutions

<abstract> <p>We are devoted to the physical analysis of the habitat area of warm-blooded organisms – humans and many mammals. For this purpose, the establishment of equilibrium distribution of carbon dioxide in aqueous solutions of salts in contact with atmospheric air starting from some time is investigated. More precisely, the relaxation time of carbon dioxide, as a function of temperature and pH, is investigated. It is found that the pH-relaxation time <italic>τ<sub>S</sub></italic> is a very nontrivial function of temperature, pH values, and NaCl salt concentration. It was assumed that the minimum value of pH relaxation time corresponds to the optimal rate of physical processes in living matter. Using this selection principle and our experimental data, we have shown that the optimal temperature for human and mammalian life activity is close to <italic>T<sub>o</sub></italic> ≈ 37 °C. The lower and upper temperature limits for their possible activity are close to <italic>T<sub>l</sub></italic> ≈ 30 °C and <italic>T<sub>u</sub></italic> ≈ 42 °C, respectively. The optimal value of <italic>pH</italic><sub>o</sub>, determined by the same selection principle, also becomes true if supplemented by the influence of albumin and other proteins.</p> </abstract>

Paper-based manganese and β-cyclodextrin sensors for colorimetric sulfur dioxide detection

Reported herein is a novel detection method for sulfur dioxide in aqueous solutions, in which the presence of sulfur dioxide leads to color changes of filter paper modified with both β-cyclodextrin and manganese. This detection method is rapid (less than 5 min required for complete color change), sensitive (limits of detection as low as 33 ppm), broadly applicable (tolerant of a range of pH values), and practical (color changes can be observed via naked eye detection and quantified via straightforward color analysis). Extensive optimization of each component provides insight into the unique stabilizing effect of cyclodextrin in preventing the filter paper from permanganate-induced degradation, and mechanistic analysis points to an oxidation-reduction reaction as responsible for the observed color changes. Overall, these results lay the groundwork for the development of practical sulfur dioxide sensors for use in the food and beverage industry, and provide precedent for the use of cyclodextrin as a stabilizing force in paper-based chemical sensors.

Measurement of the Absorption Rates of Carbon Dioxide in Aqueous Solutions of Piperazine and Sulfolane Using the Stopped-flow Technique

With the accelaration of the exploitation of natural gas reservoirs, the efficient removal of contaminants such as CO2, H2S, RSH, and COS is becoming of critical importance. In recent years, there is a growing interest in using amine blends or mixed solvents instead of a single amine for gas sweetening processes. Mixed solvents composed of a chemical solvent and a physical solvent take advantage of the benefits of both physical and chemical absorptions. The study of the absorption kinetics of the mixed solvent are necessary for designing and optimizing the process for removal of CO2 from natural gas, synthesis gas, or reformer gas. As a physical solvent, Sulfolane has excellent stability and low corrosiveness, in addition to a high capability for CO2 absorption. Sulfinol is a comercially successful process used in more than 200 plants and based on the use of Sulfolane as a physical solvent and either Diisopropanolamine (DIPA) or Methyldiethanolamine (MDEA) as chemical solvents. Mixed Sulfolane-based solvents have recently been proposed for post-combustion CO2 capture. In this study, the reaction kinetics of carbon dioxide (CO2) in aqueous solutions of aqueous piperazine (PZ) and an aqueous mixed solvent of (PZ + Sulfolane) were measured using the stopped flow technique resulting in the meaurement of observed pseudo-first-order rate constants (k0) allowing for the calculation of the second-order reaction rate constants (k2). The experiments were carried out over) concentration ranges of (10 to 60) for PZ, and (10 to 40, 10 to 200) (mol/m3) for PZ and Sulfolane, respectively and temperatures ranging from (298.15 to 313.15) K. Results show that the kinetic rates of the mixed solvent (PZ + Sulfolane + Water) were higher than those in aqueous PZ at all temperatures. The reaction kinetics in aqueous mixed solents of (PZ + Sulfolane) in reaction with CO2 increase with increasing temperature and concentration. The Termolecular mechanisms correlated the aqueous mixed systems of (PZ + Sulfolane) successfully. The reaction kinetics increased with the increase in temperature and concentration. The addition of Sulfolane to aqueous PZ resulted in increased absorption rates. Thus, the mixed solvent of PZ, Sulfolane and water can be considered an attractive alternative to aqueous amines for the enhancement of CO2 capture.

Lignin-Derived Non-Heme Iron and Manganese Complexes: Catalysts for the On-Demand Production of Chlorine Dioxide in Water under Mild Conditions.

A lignin-derived ligand, bis(2-hydroxy-3-methoxy-5-propylbenzyl)glycine (DHEG), was synthesized from 2-methoxy-4-propylphenol (dihydroeugenol (DHE)) and the amino acid glycine. Two mononuclear iron and manganese complexes of DHEG were prepared, characterized, and employed for the oxidation of chlorite to chlorine dioxide in aqueous solution. Peroxyacetic acid (PAA) was used as a "green" oxidant in the redox reactions to initiate the formation of high-valent Fe and Mn (IV)-OH intermediates. EPR studies verified the formation of a high-valent MnIV species. Both Fe and Mn complexes catalyzed chlorite oxidation with bimolecular rate constants of 32 and 144 M-1 s-1, respectively, at pH 4.0 and 25 °C. The Mn complex was found to be more efficient for chlorite oxidation with a turnover frequency of 17 h-1 and remained active during subsequent additions of PAA. The rate of ClO2 decomposition with PAA/Mn-DHEG was first order in PAA and increased significantly as pH increased. A mechanism that accounts for all observations is presented.

A reaction density functional theory study of solvent effect in the nucleophilic addition reactions in aqueous solution

Whereas the proper choice of reaction solvent constitutes the cornerstone of the green solvent concept, solvent effects on chemical reactions are not mechanistically well understood due to the lack of feasible molecular models. Herein, by taking the case study of nucleophilic addition reaction in aqueous solution, we extend the proposed multiscale reaction density functional theory (RxDFT) method to investigate the intrinsic free energy profile and total free energy profile, and study the solvent effect on the activation and reaction free energy for the nucleophilic addition reactions of hydroxide anion with methanal and carbon dioxide in aqueous solution. The predictions of the free energy profile in aqueous solution for these two nucleophilic addition reactions from RxDFT have a satisfactory agreement with the results from the RISM and MD-FEP simulation. Meanwhile, the solvent effect is successfully addressed by examining the difference of the free energy profile between the gas phase and aqueous phase. In addition, we investigate the solvent effect on the reactions occurred near solid–liquid interfaces. It is shown that the activation free energy is significantly depressed when reaction takes place in the region within 10 Å distance to the substrate surface owing to the decrease of hydration free energy at the solid–liquid interface.

An extensive thermodynamic study on amino acids aqueous solutions and their CO2 solubility by taking into account dipolar and quadrupolar contributions

Amino acids are significant biological components that in water form predominant species named zwitterions. They are highly dipolar molecules with negative and positive charges. Aqueous solutions of amino acids have numerous practical applications where knowing their thermodynamic behavior is essential to model, design, and optimize processes concerned with them. Although, dipole-dipole interactions play important roles in aqueous solution of amino acids, dipole-quadrupole and quadrupole-quadrupole ones make significant contributions when considering the solubility a highly quadrupolar component such as carbon dioxide in aqueous solution of amino acids, i.e., CO2 capture by an amino acid aqueous solution. According to the literature, there is still room to apply a more simple and effective thermodynamic model considering dipole-dipole interactions for water + amino acid systems where this work did so by applying Cubic-Plus-Polar (CPP) Equation of State (EoS). Moreover, water + amino acid + carbon dioxide systems were thermodynamically modeled by taking into account dipole-dipole, dipole-quadrupole, and quadrupole-quadrupole contributions which such investigation has not yet been carried out in the literature. The predictive capability of the proposed model were extensively examined by evaluating the model-calculated data of activity coefficient, osmotic coefficient, density, and water activity of numerous aqueous solutions of amino acids including glycine, alanine, α-aminobutyric acid, valine, serine, proline, threonine, leucine, cysteine, methionine, glutamic acid, histidine, and arginine at various temperatures. The osmotic coefficient of water + valine + alanine and water + valine + glycine systems were also predicted by CPP EoS. The solubility of CO2 in aqueous solution of methionine was finally calculated by the proposed model over a wide range of pressure. The quantitative and qualitative results provided by CPP EoS verified its reliability in all studied situations.

Reduction of dissolved carbon dioxide in aqueous solution by UV-LED/TiO2 process under periodic illumination

The application of controlled periodic illumination (CPI) using ultraviolet light-emitting diodes (UV-LED) for the photocatalytic reduction of CO2 in the aqueous phase was investigated in this study. The experiments were conducted with P-25 TiO2 as photocatalyst under the UV light intensity of 160 mW/cm2 with 60 min of total illumination time and pH 2. The target product of the photocatalytic reduction of CO2 by UV-LED process was methanol with the highest selectivity of 28.31 %. The reduction efficiency of CO2 and the reaction rate reached the highest value of 86.31 % and 15.76 × 10−5 M min−1, respectively, for experiment conducted with the smallest duty cycle of 0.09. The photonic efficiency was enhanced from 0.47 % to 2.7 % with decreasing duty cycle from 1.00 to 0.09. The electric energy saving increased significantly from 13.11%–93.34%, including with a decrease of electric energy per order from 139.68 to 10.71 kW h m-3 order-1 for experiments conducted with decreasing γ from 0.91 to 0.09. The photocatalytic reduction of CO2 in the aqueous phase was well modeled by the Langmuir-Hinshewood kinetic equation. Furthermore, the proposed mechanism for photocatalytic CO2 reduction in aqueous phase under CPI was introduced.

Formation of the Reactive Species of Oxygen, Nitrogen, and Carbon Dioxide in Aqueous Solutions under Physical Impacts

A concept is proposed, according to which the water‒air system is an open nonequilibrium system capable of accumulating free energy; the latter can be released under certain weak resonance effects via standard high-energy processes. These processes break chemical bonds and cause formation of reactive species of oxygen, nitrogen, and carbon dioxide.

Absorption of CO2 in aqueous blend of methyldiethanolamine and arginine

AbstractThe objective of this research is to study for the first time the effect of adding l‐arginine (Arg) amino acid on the solubility of carbon dioxide in aqueous solution of N‐methyldiethanolamine (MDEA). The study was carried out at different mixing ratios of MDEA and Arg at a total concentration of 2 moles per litre. The CO2 partial pressure varied from about 10 to 100 kPa, and the temperature varied from 293 K to 323 K. The experimental results showed improved solubility of CO2 with the addition of Arg at CO2 partial pressures below 20 kPa. However, for CO2 partial pressure of above 20 kPa, the addition of Arg caused a decrease in the solubility of CO2. The obtained loading data were correlated using a semiempirical (SE) vapour liquid equilibrium (VLE) model with an average absolute deviation (AAD) less than 4.1% between the predicted and the experimental values. An estimation of the heat of CO2 absorption in the solution was obtained using an analytical expression for ΔHabs derived from the SE model and was found to be in the range of 29‐ to 40‐kJ/mole CO2. From the finding of this work, it is anticipated that the studied novel blended solvent will effectively reduce CO2 capture costs as the CO2 content of most gas streams is less than 20% by volume, which is specifically true for natural gas and a large number of industrial flue gas streams.

Measuring and modeling equilibrium solubility of carbon dioxide in aqueous solution of dimethylaminoethanol and 3-methylaminopropylamine

The equilibrium solubility of carbon dioxide in an aqueous mixture comprised of 40 wt.% dimethylaminoethanol (DMAE) and 5 wt.% 3‒(Methylamino)propylamine (MAPA) was measured at temperatures (313.15, 328.15, 343.15, and 358.15) K and in the total pressure range of (7.9–359.7) kPa. The heat of absorption of carbon dioxide in the aqueous solution was measured at 328.15 K. Equilibrium constant of reaction of formation of carbamate by MAPA was measured experimentally in the temperature range of (298.15–333.15) K. The Deshmukh‒Mather thermodynamic model was applied to correlate the equilibrium solubility data. The small value of average absolute percent deviation (AAD% = 2.56) of the correlated values from experimental data implies good correlative accuracy of the Deshmukh–Mather model. The tuned model was also used to calculate the heat of absorption of carbon dioxide into the aqueous solution of DMAE + MAPA. The AAD% of calculated heat of absorption from the measured values was 3.91.

Experimental measurement and prediction of carbon dioxide clathrate hydrate phase boundary in presence of ethanol + sodium chloride, potassium chloride, magnesium chloride and calcium chloride aqueous solution

The dissociation condition of clathrate hydrate of carbon dioxide in aqueous solutions of ethanol + NaCl, KCl, MgCl2 and CaCl2 are measured in the temperature range of (259.4–274.7) K and pressures up to 3.7 MPa. Isochoric pressure-search method is used for all measurements. In addition for the first time in open literature a machine learning algorithm model based on artificial neural network is developed to predict equilibrium temperatures. Absolute relative deviation (ARD) and correlation coefficient (R2) for trained neural network are 0.0305 and 0.9994, respectively.

Experimental modeling of the solubility of carbon dioxide in aqueous solution of monoethanolamine +1, 3-diaminopropane

The solubility of carbon dioxide in aqueous solutions of 10 wt% MEA + 5 wt% DAP and 12.5 wt% MEA + 2.5 wt% DAP is measured over a temperature range of 313.15 to 333.15 K and pressure ranging from 13 to 215 kPa using pressure decay method. The solubility of CO2 increases by decreasing temperature at constant pressure and increasing pressure at constant temperature. The results showed that CO2 solubility increases with increasing DAP concentration. The Kent-Eisenberg improved model is used to correlate experimental results with good agreement.

Structure, Dynamics, and Hydration Free Energy of Carbon Dioxide in Aqueous Solution: A Quantum Mechanical/Molecular Mechanics Molecular Dynamics Thermodynamic Integration (QM/MM MD TI) Simulation Study.

The solvation of carbon dioxide in solution represents a key step for the capture and fixation CO2 in nature, which may be further influenced by the formation of (bi)carbonate species and/or the formation of CO2 clusters in solution. The latter processes are strongly dependent on the exact environment of the liquid state (e.g., pH value, solvated ions, etc.) and may interfere with the experimental determination of structural, dynamical, and thermodynamic properties. In this work a hybrid quantum mechanical/molecular mechanical (QM/MM) simulation approach at correlated ab initio level of theory resolution-of-identity second-order Møller-Plesset Perturbation Theory (RI-MP2) has been applied in the framework of thermodynamic integration (TI) to study structure, dynamics, and the hydration free energy of a single carbon dioxide molecule in aqueous solution. A detailed analysis of the individual QM/MM potential energy contributions demonstrate that the overall potential remains highly consistent over the entire sampling phase and that no artificial contributions are influencing the determination of the hydration free energy. The latter value of 0.01 ± 0.92 kcal/mol was found in very good agreement with the values of 0.06 and 0.24 kcal/mol obtained via quasi-chemical theory and experimental measurements, respectively. In order to obtain detailed information about the C- and O C-water interaction, conically restricted regions with respect to the main axis of the CO2 molecule have been employed in structural analysis. The presented data not only provide detailed information about the hydration properties of CO2 but act as a critical validation of the simulation technique, which will be beneficial in the study of nonaqueous solvents such as pure and aqueous NH3 solutions, which have been suggested as potential candidates to capture CO2 from anthropogenic sources.

Carbon-carbon bond formation in the reaction of hydrated carbon dioxide radical anions with 3-butyn-1-ol

Electrochemical activation of carbon dioxide in aqueous solution is a promising way to use carbon dioxide as a C1 building block. Mechanistic studies in the gas phase play an important role to understand the inherent chemical reactivity of the carbon dioxide radical anion. Here, the reactivity of CO2−(H2O)n with 3-butyn-1-ol is investigated by Fourier transform ion cyclotron (FT-ICR) mass spectrometry and quantum chemical calculations. Carbon-carbon bond formation takes places, but is associated with a barrier. Therefore, bond formation may require uptake of several butynol molecules. The water molecules slowly evaporate from the cluster due to the absorption of room temperature black-body radiation. When all water molecules are lost, butynol evaporation sets in. In this late stage of the reaction, side reactions occur including H atom transfer and elimination of HOCO.

Effects of piperazine concentration and operating conditions on the solubility of CO2 in AMP solution at low CO2 partial pressure

ABSTRACTIn this study, new equilibrium solubility data for carbon dioxide in aqueous solutions of 2-amino-2-methyl-1-propanol and piperazine (PZ) are provided. The two famous Deshmukh–Mather and Kent Eisenberg thermodynamic models are utilized to predict the CO2 absorption. The experimental data show that the solubility of CO2 decreases as the temperature increases. Our data suggest that the addition of PZ has different effects on CO2 absorption under different partial pressure of the CO2 in the gas stream. For high partial pressure, the addition of PZ promotes the absorption performance. However, at low CO2 partial pressure, PZ addition results in less saturated CO2 loading. The Deshmukh–Mather model can provide an accurate prediction of the experimental data at high partial pressure of CO2 (i.e. AAD = 3.4%) whereas the modified Kent–Eisenberg model can capture the inverse effects of the PZ at low partial pressure and provides a relatively good approximation of experimental data at low partial pressure (i.e. AAD = 10%).

Immobilized carbonic anhydrase: preparation, characteristics and biotechnological applications.

Carbonic anhydrase (CA) is an essential metalloenzyme in living systems for accelerating the hydration and dehydration of carbon dioxide. CA-catalyzed reactions can be applied in vitro for capturing industrially emitted gaseous carbon dioxide in aqueous solutions. To facilitate this type of practical application, the immobilization of CA on or inside solid or soft support materials is of great importance because the immobilization of enzymes in general offers the opportunity for enzyme recycling or long-term use in bioreactors. Moreover, the thermal/storage stability and reactivity of immobilized CA can be modulated through the physicochemical nature and structural characteristics of the support material used. This review focuses on (i) immobilization methods which have been applied so far, (ii) some of the characteristic features of immobilized forms of CA, and (iii) biotechnological applications of immobilized CA. The applications described not only include the CA-assisted capturing and sequestration of carbon dioxide, but also the CA-supported bioelectrochemical conversion of CO2 into organic molecules, and the detection of clinically important CA inhibitors. Furthermore, immobilized CA can be used in biomimetic materials synthesis involving cascade reactions, e.g. for bone regeneration based on calcium carbonate formation from urea with two consecutive reactions catalyzed by urease and CA.