Solubility of carbon dioxide in aqueous solution of 2-amino-2-methyl-1-propanol and piperazine

In this work, new experimental results of the vapour-liquid equilibrium (VLE) of CO₂ in aqueous 2-amino-2-methyl-1-propanol (AMP) and piperazine (PZ) have been presented in the temperature range of 298-328 K and PZ concentration range of 2-8 mass%, keeping the total amine concentration in the solution at 30 mass%. The partial pressures of CO₂ were in the range of 0.1-1450 kPa. A thermodynamic model was developed to correlate and predict the VLE of CO₂ in aqueous AMP + PZ. The electrolyte nonrandom two liquid (ENRTL) theory has been used to develop the VLE model for the quaternary system (CO₂ + AMP + PZ + H₂O) to describe the equilibrium behaviour of the solution. The experimental data from this work and data available in the literature were used to regress the ENRTL interaction parameters. The model predictions are in good agreement with the experimental data of CO₂ solubility in aqueous blends of this work as well as those reported in the literature. The current model can also predict speciation, heat of absorption, pH of the CO₂ loaded solution, and amine volatility.     

Reaction between carbon dioxide and elementary fluorine

Reactions between carbon dioxide and fluorine were examined at temperatures of 303-523 K under various pressure and mixture ratios of both gases. Reactions were carried out similarly under the existence of NaF, CsF and EuF₃.After the reaction, fluorine was removed and the reaction products were analyzed using FT-IR, GC/FT-IR and GC/MS. The major products were CF₃OF, COF₂, CF₄ and CF₂(OF)₂.The best yield of COF₂ was 11.1% under the reaction condition of CO₂/F₂ = 76 kPa/76 kPa with temperature of 498 K for 72 h in a direct reaction. The formation rate of COF₂ in the direct reaction was estimated as 0.232 dm³ mol⁻¹ h⁻¹ under the reaction conditions of CO₂/F₂ = 76 kPa/76 kPa, at 498 K. In the presence of CsF, it was estimated as 1.88 dm³ mol⁻¹ h⁻¹ at CO₂/F₂ = 76 kPa/76 kPa at 498 K.The activation energy of the COF₂ formation in the direct reaction was estimated as 45.7 kJ mol⁻¹ at CO₂/F₂ = 76 kPa/76 kPa at 498 K. In addition, 24.2 and 38.9 kJ mol⁻¹ were evaluated at CO₂/F₂ = 76 kPa/76 kPa at 498 K, respectively, in the presence of CsF and EuF₃.     

Phase diagram of Na2S2O3 + ethanol + water at ambient pressure and temperature

In the present communication, we report the studies concerning liquid–liquid–solid equilibria for the ternary system sodium thiosulphate (Na₂S₂O₃) + ethanol + water at ambient pressure and at room temperature (303 ± 2 K). The solubility data of Na₂S₂O₃ are reported for solutions in water, ethanol and solutions of varying concentrations of ethanol in water. The phase diagram for the said system is developed, described and compared with similar system K₂CO₃ + methanol + water. These results have been explained in terms of structural properties of aqueous ethanol solutions and further discussed in terms of the effect of ions to cause phase separation.     

Solid–liquid equilibria for binary and ternary systems with the Cubic-Plus-Association (CPA) equation of state

A systematic investigation of the CPA model’s performance within solid–liquid equilibria (SLE) in binary mixtures (methane + ethane, methane + heptane, methane + benzene, methane + CO₂, ethane + heptane, ethane + CO₂, 1-propanol + 1,4-dioxane, ethanol + water, 2-propanol + water) is presented. The results from the binary mixtures are used to predict SLE behaviour in ternary mixtures (methane + ethane + heptane, methane + ethane + CO₂). Our results are compared with experimental data found in the literature.     

Facile fabrication of a novel high performance CO2 separation membrane: Immobilization of poly(amidoamine) dendrimers in poly(ethylene glycol) networks

Poly(amidoamine) (PAMAM) dendrimers showed high CO₂ separation properties and were successfully immobilized in a poly(ethylene glycol) (PEG) network upon photopolymerization of PEG dimethacrylate. The PAMAM dendrimer incorporation ratio was readily controlled, and a stable self-standing membrane containing up to 75 wt.% PAMAM dendrimer was obtained. The CO₂ separation properties over smaller H₂ were investigated by changing the PAMAM dendrimer content or generation and CO₂ partial pressure (ΔPCO₂$\mathrm{\Delta }{P}_{\text{C}{\text{O}}_2}$) under atmospheric conditions. Especially, a polymeric membrane containing 50 wt.% PAMAM dendrimer (0th generation) exhibited an excellent CO₂/H₂ selectivity of 500 with CO₂ permeability of 2.74 × 10⁻¹⁴ m³(STP)m/(m² s Pa) or 3.65 × 10³ barrer (1 barrer = 7.5 × 10⁻¹⁸ m³(STP)m/(m² s Pa)) when a mixture gas (CO₂/H₂: 5/95 by vol.) was fed at 25 °C and 100 kPa with 80% relative humidity. This polymeric materials are promising for a novel CO₂ separation membrane.     

Isobaric vapor-liquid equilibrium for binary systems containing benzothiophene

Isobaric vapor-liquid equilibrium (VLE) of the following systems was measured with a recirculation still: benzothiophene + dodecane at 99.6 kPa, benzothiophene + 1-dodecene at 100.1 kPa, and benzothiophene + 1-octanol at 100 kPa. All systems studied exhibit positive deviation from Raoult's law. A minimum temperature azeotrope was found in the systems benzothiophene + dodecane (x₁ = 0.491, P = 99.6 kPa, T = 484.72 K) and benzothiophene + 1-dodecene (x₁ = 0.185, P = 100.1 kPa, T = 484.45 K). No azeotropic behavior was found in benzothiophene + 1-octanol system at 100 kPa. The experimental results were correlated with the Wilson model and compared to COSMO-SAC predictive model. Liquid and vapor phase compositions were determined with gas chromatography. All measured data sets passed the thermodynamic consistency tests. The activity coefficients at infinite dilution are also presented.     

High-pressure phase behaviour of binary (CO2 + nicotine) and ternary (CO2 + nicotine + solanesol) mixtures

This work paper presents vapour–liquid equilibrium (VLE) data for binary (CO₂ + nicotine) and ternary (CO₂ + nicotine + solanesol) mixtures, at 313.2 K and 6, 8 and 15 MPa. The (CO₂ + nicotine) system exhibits three phases (L₁L₂V) in equilibrium at 8.37 MPa. It is estimated that this system most likely follows the type-III phase behaviour. In the ternary system, the presence of solanesol in the vapour phase was detected only at the pressure of 15 MPa. At this pressure, partition coefficients and separation factors for solanesol/nicotine were calculated for different initial nicotine/solanesol compositions and a strong influence of composition was found. The results were modelled using the Peng–Robinson equation of state (PR EOS) coupled with the Mathias–Klotz–Prausnitz (MKP) mixing rule (PR–MKP model). Good correlations of the binary data, particularly in the case of the (CO₂ + nicotine) mixture, were obtained. However, the model could not correlate the ternary data.     

Ash properties of Pinus halepensis needles treated with diammonium phosphate

The ash properties of Pinus halepensis (Aleppo pine) needles before and after treatment with diammonium phosphate (NH₄)₂HPO₄ (DAP) have been investigated, using thermogravimetric analysis (TG), differential thermal analysis (DTA), titrimetry, inductively coupled plasma-emission spectrometry (ICP-ES), X-ray diffraction (XRD) and scanning electron microscopy (SEM). DAP is extensively used as active component in wildland fire retardants.The following crystalline compounds have been identified in ashes prepared at 600 °C before treatment with DAP: KCl, Ca(OH)₂, MgO, (CaMg)CO₃, K₂CO₃·CaCO₃, K₂CO₃, K₂SO₄, CaO and CaCO₃, whereas CaO, MgO, K₂SO₄, K₂CO₃, CaCO₃, KCl and CaO, MgO, K₂SO₄ and K₂CO₃ at 800 and 1000 °C, respectively. The presence of DAP alters the composition of ashes converting, almost completely at high temperatures, the metallic oxides into phosphate salts. Thus, decreasing their alkalinity. The micrographs obtained by SEM indicate that pine needles ashes contain large porous particles of carbon compounds and several inorganic particles of irregular shape <1.0 mm, whereas after treating the needles with DAP an amorphous rigid structure was formed.To facilitate our investigation model mixtures of CaCO₃ + DAP, MgCO₃ + DAP, K₂CO₃ + DAP were heat treated under the same conditions used for preparing the ashes. The chemical transformations taken place during heating were studied by analysing the reaction products using thermal analysis and XRD.The physical, mineralogical and chemical forest ash properties determined could be used to evaluate the environmental risk of the use of fire retardants on soils, plants and aquatic systems as well as to investigate the mechanism of combustion of forest fuels in the presence of DAP.     

A comparative study of the effects of different buffer gases on the line shape of water vapour rovibronic transition

The line shape parameters of water vapour rovibrational transition at 12145.444 cm⁻¹ belonging to the (2ν₁ + ν₂ + ν₃) overtone band in the presence of three buffer gases He, N₂ and CO₂ are studied by high resolution near infrared (NIR) diode laser spectrometer. The wavelength modulation spectroscopy (WMS) is adopted to probe buffer gas broadened first derivative (1f) signal of water vapour transition. The simulation of the experimental signals based on Voigt profile provides the collisional broadening coefficients and line strength parameters. The comparison is made between the broadening effects on water vapour transition induced by He, N₂ and CO₂.     

The solid state reaction between lanthanum oxide and strontium carbonate

The reaction between lanthanum oxide and strontium carbonate was studied non-isothermally between 350 and 1150 °C at different heating rates, intermediates and the final solid product were characterized by X-ray diffractometry (XRD). The reaction proceeds through formation of lanthanum oxycarbonate La₂O(CO₃)₂, lanthanum dioxycarbonate La₂O₂CO₃, and non-stoichiometric strontium lanthanum oxide La₂SrO_x (x = 4 + δ). La₄SrO₇ was found to be the final product which begins to form at ∼700 °C. Li⁺ doping enhances the formation of the final product as well as commencement of the reactions at lower temperatures.     

New isothermal vapor–liquid equilibria for the CO2 + n-nonane,and CO2 + n-undecane systems

Experimental vapor–liquid equilibria (VLE) for the CO₂ + n-nonane and CO₂ + n-undecane systems were obtained by using a 100-cm³ high-pressure titanium cell up to 20 MPa at four temperatures (315, 344, 373, and 418 K). The apparatus is based on the static-analytic method; which allows fast determination of the coexistence curve. For the CO₂ + n-nonane system, good agreement was found between the experimental data and those reported in literature. No literature data were available for the CO₂ + n-undecane system at high temperature and pressure. Experimental data were correlated with the Peng–Robinson equation of state using the classical and the Wong–Sandler mixing rules.     

High-pressure vapor–liquid equilibria for CO2 + alkanol systems and densities of n-dodecane and n-tridecane

An apparatus based on the static-analytic method was used to measure the vapor–liquid equilibria (VLE) for CO₂ + alkanol systems. Equilibrium measurements for the CO₂ + 1-propanol system were performed from 344 to 426 K. For the case of the CO₂ + 2-propanol system, measurements were made from 334 to 443 K, and for the CO₂ + 1-butanol were obtained from 354 to 430 K. VLE data were correlated with the Peng–Robinson equation of state using the classical and the Wong–Sandler mixing rules. Moreover, compressed liquid densities for the n-dodecane and n-tridecane were obtained via a vibrating tube densitometer at temperatures from 313 to 363 K and pressures up to 25 MPa. The Starling and Han (BWRS), and The five-parameter Modified Toscani-Swarcz (MTS) equations were used to correlate them. The experimental density data were compared with those from literature, and with the calculated values obtained from available equations for these n-alkanes.     

Vapour–liquid equilibrium for β-myrcene and carbon dioxide and/or hydrogen and the volume expansion of β-myrcene or limonene in CO2 at 323.15 K

Vapour–liquid equilibrium measurements for binary and ternary (carbon dioxide + β-myrcene and carbon dioxide + β-myrcene + hydrogen) systems have been carried out at 323.15 K and pressures in the range from 7 MPa to the critical pressure of the binary mixture and at pressures from 10 to 14 MPa for the investigated ternary systems. Samples from the coexisting phases were taken, and compositions were determined experimentally. Results were correlated using the Peng–Robinson and the Soave–Redlich–Kwong equations of state with the Mathias–Klotz–Prausnitz mixing rule. The set of interaction parameters for the employed equations of state and applied mixing rule for the system of CO₂ + β-myrcene and of CO₂ + β-myrcene + H₂ were obtained. Additionally, the volume expansion of the liquid phase for the binary mixtures (carbon dioxide + β-myrcene and carbon dioxide + limonene) were measured at 323.15 K and at pressures from 4 MPa up to very close to the critical pressure of the mixture. The ratio of liquid phase total volumes at the given pressure and at 4 MPa was calculated.     

Physical Characteristics and Microbial Quality of Ostrich Meat in Relation to the Type of Packaging and Refrigerator Storage Time

The aim of this study was to evaluate the effect of the packaging system type on the physical characteristics and microbial changes in ostrich meat during refrigerated storage. The applied packaging systems were vacuum packaging (VP) and modified atmosphere packaging (MAP) using two combinations of gases: MAP1 (40% O₂/40% CO₂/20% N₂) and MAP2 (60% O₂/30% CO₂/10% N₂). Eight meat samples were obtained in three replicates for all parameters, except for pH, for which six replicates were obtained from the M. ilifibularis (IF) muscle, and were stored in a refrigerator at 2 °C and analyzed at 0, 4, 8, 12 and 16 days for the effect of packaging methods on physical meat quality. The initial pH (5.99) decreased at the end of the storage time for MAP1 to 5.81, whereas VP was stable from day 0 to 12 and increased up to 6.08 on day 16. Regarding meat color, the L* value increased during storage for MAP1 and MAP2 from 36.99 to 40.75 and 41.60, respectively, whereas it declined for VP to 34.22. The same tendencies were reported for redness (a*) and yellowness (b*). Drip loss was the lowest in MAP1 and highest in VP. The lowest total viable bacteria counts were identified in VP, as compared to MAP1 and MAP2.     

The DFT and ab initio investigations on the mechanism of CF3O2 + H reaction

The mechanisms for the reaction of CF₃O₂ with atomic hydrogen were studied with ab initio and DFT methods. The results reveal that the reaction could take place on the singlet and triplet potential energy surfaces (PES). For the singlet PES, addition/elimination and substitution mechanisms are determined, and the former one is dominant. The most favorable channel involves the association of CF₃O₂ with H atom to form CF₃O₂H (IM1) via a barrierless process, and then the O–O bond dissociates to give out CF₃O + OH. The secondary product might be CF₃OH + O, formed from the O–O bond cleavage in the initial adduct CF₃O(H)O (IM2). Other products such as CF₃ + O₂H, HF + CF₂O₂ and O₂ + CHF₃ are of no importances because of higher barriers. On the triplet PES, only substitution mechanism is located. With higher barriers involving, the channels on the triplet PES could be negligible compared with the channels on the singlet PES.     

Thermodynamic stability of Sr2CeO4

Thermochemistry of the reaction between SrCO₃ and SrCeO_3, represented as

SrCO₃(s) + SrCeO₃(s) = Sr₂CeO₄(s) + CO₂(g),     

Equilibrium solubility of carbon dioxide in 2(methylamino)ethanol

In this paper the equilibrium solubility of carbon dioxide in 1.0 M, 2.0 M and 4.0 M 2(methylamino)ethanol (MAE) is measured at 303, 313 and 333 K, and at CO₂ partial pressures ranging from 1 to 100 kPa using stirred cell reactor. The Kent-Eisenberg model was used to predict the solubility of carbon dioxide in MAE solutions. The equilibrium constant representing hydrolysis of carbamate ion is correlated with temperature, CO₂ partial pressure and amine concentration by non-linear regression, using experimental results of carbamate ion concentrations. The model predicted results showed good agreement with the experimental solubility results. The solubility profile of CO₂ in MAE showed better performance when compared with other commercial amines.     

Measurement and correlation of solubilities of C.I. Disperse Red 73, C.I. Disperse Yellow 119 and their mixture in supercritical carbon dioxide

The solubilities of disperse dyes and their mixture in supercritical carbon dioxide are important to the fundamental research and development of supercritical fluid dyeing (SFD). The solubilities of Disperse Red 73, Disperse Yellow 119 and their mixture in supercritical carbon dioxide were measured in the temperature range from 343 to 383 K and pressures from 12 to 28 MPa by a static-recirculation method. The results show that over the entire range of experimental conditions in the binary (Disperse Red 73 + CO₂ and Disperse Yellow 119 + CO₂) and ternary (Disperse Red 73 + Disperse Yellow 119 + CO₂) systems, the solubilities increased with increasing pressure and temperature and were clearly affected by the molecular polarity of the dyes. A co-solvent effect and a competing dissolution effect existing in the ternary system led to the increase and decrease in the solubilities of Disperse Yellow 119 and Disperse Red 73, respectively. The solubility data of the two dyes and their mixture were correlated with two empirical models—the Chrastil and the Mendez-Santiago/Teja (MT) model.     

High-pressure phase behavior of CO2 + 1-butyl-3-methylimidazolium chloride system

The phase behavior of carbon dioxide (CO₂) and the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride ([bmim][Cl]) was measured and correlated at high pressures up to ∼40 MPa and at temperatures between 353.15 K and 373.15 K. The solubility data of CO₂ in [bmim][Cl] were obtained by observing the bubble point pressure at specific temperatures. A variable-volume view cell, which is a high-pressure equilibrium apparatus, was used to measure the CO₂ + [bmim][Cl] system solubility under varying pressure and temperature conditions. In addition, liquid–liquid–vapor (LLV) three-phase behavior was investigated using the equilibrium cell to be able to determine the classification of phase-behavior type by Scott and Van Konynenburg. Based on the LLV phase behavior, this system most likely has type III phase-behavior which is common for IL + CO₂ systems. The resulting data showed that CO₂ dissolved well in the IL at low CO₂ concentrations, but that the pressure derivative of CO₂ solubility dramatically decreased as the mole fraction of CO₂ was increased. The experimental data were well fitted by the Peng–Robinson equation of state with a quadratic mixing rule and cubic parameters estimated by the Joback method.     

Syntheses and characterization of ANi(AsF6)3 (A = H3O, O2, NO, NH4, K, Rb, and Cs) compounds

ANi(AsF₆)₃ (A = O₂⁺, NO⁺, NH₄⁺) compounds could be prepared by reaction between corresponding AAsF₆ salts and Ni(AsF₆)₂. When mixtures of AF (A = Li, Na, K, Rb, Cs) and NiF₂ are dissolved in aHF acidified with an excess of AsF₅ the corresponding AAsF₆ and Ni(AsF₆)₂ were formed in situ. For A = Li and Na only mixtures of AAsF₆ and Ni(AsF₆)₂ were obtained, while for A = K, Rb and Cs, the final products were ANi(AsF₆)₃ (A = K-Cs) compounds contaminated with AAsF₆ (A = K-Cs) and Ni(AsF₆)₂.ANi(AsF₆)₃ (A = H₃O⁺, O₂⁺, NO⁺, NH₄⁺ and K⁺) compounds are structurally related to previously known H₃OCo(AsF₆)₃. The main features of the structure of these compounds are rings of NiF₆ octahedra sharing apexes with AsF₆ octahedra connected into infinite tri-dimensional network. In this arrangement cavities are formed where single charged cations are placed.In O₂Ni(AsF₆)₃ the vibrational band belonging to O₂⁺ vibration is found at 1866 cm⁻¹, which is according to the literature data one of the highest known values, and it is only 10 cm⁻¹ lower than the value for free O₂⁺.