Aqueous Sodium Glycinate Research Articles

Density and Viscosity of Potassium and Sodium Glycinate Solutions

Among the features of solvents, density and viscosity are essential to consider in the design of new absorption facilities and estimate properties such as diffusivity. In the present work, the density and viscosity of potassium glycinate aqueous solutions and sodium glycinate aqueous solutions [4–40 wt %] have been measured from 288.15 to 323.15 K. From these data, it can be concluded that potassium glycinate solutions are less viscous (by 16.5% on average for 1.0 mol/kg solvent) than sodium glycinate solutions. A comparison with other solutions of amino acid salts leads to the conclusion that glycinate solutions have relatively low viscosities, which can reduce the capital and operating costs of carbon dioxide (CO2) capture facilities. To enable viscosity and density to be estimated accurately, three semi-empirical correlations are set up to correlate the viscosity of potassium and sodium glycinate solutions. These correlations are compared and provide accurate results of viscosity (AARD < 3.1%). Density is also correlated, and the correlation shows excellent results (AARD < 0.2%).

TEA of a Unique Two-Pathways Process for Post-Combustion CO&lt;sub&gt;2&lt;/sub&gt; Capture

A unique two-Pathways process using aqueous sodium glycinate for CO&lt;sub&gt;2&lt;/sub&gt; capture from a split flue gas stream emitted from 600 MWe post-combustion coal power plant was developed in Aspen Plus v.10. The split gas flow rate used was 44.75 ton/h and contained 0.0023 mol% SO&lt;sub&gt;2&lt;/sub&gt; and 13.33 mol% CO&lt;sub&gt;2&lt;/sub&gt;. The process includes a washing unit, a CO&lt;sub&gt;2&lt;/sub&gt; absorption unit, a reverse osmosis unit, and a solvent regeneration unit or an ultrafiltration unit. The washing unit uses deionized water to completely remove SO&lt;sub&gt;2&lt;/sub&gt; and the CO&lt;sub&gt;2&lt;/sub&gt; absorption unit uses SGS to capture at least 90 mol% of the CO&lt;sub&gt;2&lt;/sub&gt; in the split flue gas stream. Upon CO&lt;sub&gt;2&lt;/sub&gt; and SGS reactions, the resulting liquid products exhibit phase-separation into CO&lt;sub&gt;2&lt;/sub&gt;-lean phase and CO&lt;sub&gt;2&lt;/sub&gt;-rich phase, allow two distinct pathways. Pathway (i) is to regenerate mostly the CO&lt;sub&gt;2&lt;/sub&gt;-rich phase, collect the released CO&lt;sub&gt;2&lt;/sub&gt;, and compress it for sequestration purposes. Pathway (ii) is to send the liquid stream from the CO&lt;sub&gt;2&lt;/sub&gt; absorption unit to the ultrafiltration unit to separate the solid nanomaterials. The hydraulics and mass transfer characteristics in the washing and CO&lt;sub&gt;2&lt;/sub&gt; absorption units were obtained; and techno-economic analysis (TEA) for Pathways (i) and (ii), including Capital Expenditure (CAPEX), Operating Expenditure (OPEX), and Levelized Cost of CO&lt;sub&gt;2&lt;/sub&gt; Captured (LCOC), were calculated and compared. The simulation results revealed that the CAPEX, OPEX, and LCOC for Pathway (i) were ($12,039,251), (261 $/h), and (54.01 $/ton-CO&lt;sub&gt;2&lt;/sub&gt; captured), respectively, and those for Pathway (ii) were ($5,908,000), (237.2 $/h), and (39.90 $/ton-CO&lt;sub&gt;2&lt;/sub&gt; captured), respectively. Moreover, in Pathway (ii), 8.19 ton/h of CO&lt;sub&gt;2&lt;/sub&gt; were captured to produce 15.62 ton/h NaHCO&lt;sub&gt;3&lt;/sub&gt; nanomaterials, which were sold to offset the overall process cost. The LCOC values indicate that Pathway (ii) is more cost-effective than Pathway (i) because LCOC values for Pathway (ii) are much lower than those for Pathway (i).

Equilibrium solubility and kinetics of CO2 absorption in hexamethylenediamine activated aqueous sodium glycinate solvent

Equilibrium solubility and absorption kinetics of CO2 in hexamethylenediamine (HMDA) activated aqueous sodium glycinate (SG) solvent are measured in the temperature range of 313–333 K. For the experimental investigation, HMDA concentration in the solvent is varied in the range of 5–15 mass% keeping total amine concentration at 30 mass%. Solubility data is presented in the form CO2 loading (mole CO2 absorbed per mole of total amine). Kinetics of CO2 absorption is evaluated assuming pseudo first order reaction condition. Both solubility and kinetics of CO2 absorption are found to enhance significantly due to addition of small amount of HMDA in the aqueous SG solvent. CO2 loading data is correlated using modified Kent-Eisenberg model. For developing kinetic model, overall rate is assumed to be the combined rate contribution of CO2-HMDA and CO2-SG reaction system. Based on this concept, a kinetic model is proposed using zwitterion mechanism for both the component reaction system. Kinetic and solubility models developed in this work are in good agreement with the experimental data with average absolute deviation of 7.4% and 4.5% respectively.

Neural computations in modelling of CO2 capture from Gas stream emissions by Sodium Glycinate solution

ABSTRACTThe present contribution was performed in order to predict CO2 loading capacity in aqueous sodium glycinate as a novel class of green solution under wide operating range using radial basis function artificial neural network (RBFANN). The predicted CO2 loading capacity values were in brilliant agreement with those corresponding experimental values. The estimated values of MSE and R-squared were 0.00045 and 0.997, respectively. Accordingly, statistical and graphical analyses confirm satisfactory prediction of our proposed model.

ANFIS modeling of carbon dioxide capture from gas stream emissions in the petrochemical production units

ABSTRACTAmino acid salt, especially sodium glycinate, was known as a new class of environment-friendly solution that is now being studied as a favorable alternative to amines. In the present collaboration, the Adaptive Network-based Fuzzy Inference System (ANFIS) was employed to estimate CO2 loading capacity in the presence of aqueous sodium glycinate solution under broad ranges of temperature and pressure. The outcomes of suggested ANFIS model indicated their brilliant agreement with corresponding experimental values. The calculated values of mean relative error and R-squared were 2.93 and 0.988, respectively. Our suggested model can be of huge value for process engineers to have a simple and accurate tool in order to have rapid estimations of CO2 solubility as a function of temperature, pressure, and mass composition of sodium glycinate solution.

Modelling of CO2 separation from gas streams emissions in the oil and gas industries

ABSTRACTSodium glycinate solutions have low vapor pressure, low viscosity, and high chemical reactivity with CO2. They have remarkable potential for removal of CO2 from the flue gases, because absorption of CO2 with an amino acid salt solution such as sodium glycinate is accompanied with precipitation. As the liquid phase contains solid compounds during absorption of CO2, the reactions move into the production of various materials and a further amount of CO2 is absorbed. In the current study, a support vector machine algorithm is utilized to predict carbon dioxide solubility in aqueous sodium glycinate solutions over wide ranges of temperature, pressure, and concentration. The proposed model can be of immense value for engineers to have a quick check on the CO2 solubility in sodium glycinate solutions without opting for any experimental works. Results obtained from the model have shown excellent agreement with reported data in the literature.

High-pressure Solubility of Carbon Dioxide in Aqueous Sodium L- Prolinate Solution

An experimental evaluation of CO2 solubility in aqueous sodium L-prolinate (SP) solution was carried out using high-pressure solubility equipment at three different temperatures, 303.15, 313.15, and 333.15K. The study was conducted over the pressure range from 2 to 60bar for 30wt. % SP solution. It was found that, the CO2 loading (mole of CO2 / mole of SP) decreases with increasing temperature, while it increases with increasing the pressure of gas. ANOVA analysis was carried out to determine the statistical significance of the solubility data with respect to temperature and pressure. The CO2 loading of aqueous SP solution was also compared with MEA and aqueous sodium glycinate (SG) solution. It was observed that the aqueous SP solution has higher CO2 loading capacity as compared to 30wt. % MEA, and comparable with aqueous 30wt. % SG solution.

PCC pilot plant studies with aqueous potassium glycinate

The present research work discusses the suitability of aqueous potassium glycinate (KGly) in a PCC-pilot plant. Reference is made to measurement results with aqueous sodium glycinate (NaGly). The use of real power plant flue gas and the well-conceived dimensions of the test facility enable industry-related conditions for full-scale applications.Although 40wt% KGly has faster kinetics in unloaded state, no enhancements in plant operation could be achieved in comparison to 40wt% NaGly. Just like with NaGly, the difficult feasibility of KGly regeneration leads to slow CO2 absorption rates, resulting in a huge energy demand >5.5 GJ/tCO2. A far lower energy demand of 3.68 GJ/tCO2 was measured for 30wt% MEA. The required solvent flow rate for reaching the optimal operating point is high (L/G-ratio=9l/m3). The pilot plant was operated with a massive reduced flue gas flow (40% of the dimensioning) in order to prevent instable operation and to reach the desired CO2 separation efficiency of 90%. During a prolonged shutdown, excessive carbonate was formed in the desorber column, resulting in a further reduction of the flue gas flow rate. Measurements of the ammonia content of the treated flue gas exhibit that the solvent degrades enormously.

VLE of CO2 in aqueous sodium glycinate solution – New data and modeling using Kent–Eisenberg model

Vapor–liquid equilibrium (VLE) of CO2 in aqueous sodium glycinate solution (SG) is studied in this work. Equilibrium solubility data is measured experimentally in 5–25mass% aqueous sodium glycinate solution at 313.15, 323.15 and 333.15K, over the CO2 partial pressure range of 2–600kPa. Density and viscosity of aqueous sodium glycinate are also measured at same temperature range. From the experimental results it is seen that aqueous solution of SG has good CO2 loading (mole of CO2 absorbed per mole of amine) potential. Experimental VLE data is then correlated using the Kent–Eisenberg model and carbamate hydrolysis equilibrium constant and amine deprotonation equilibrium constant are regressed. Average absolute deviation between experimental and model predicted results is found to be 7.13%.

Physicochemical properties of aqueous solutions of sodium glycinate in the non-precipitation regime from 298.15 to 343.15 K

The physicochemical properties, including the density, viscosity, and refractive index of aqueous solutions of sodium glycinate as a solvent for CO2 absorption in the non-precipitation regime were measured under the wide temperature range of 298.15 to 343.15K. The concentration of the sodium glycinate in an aqueous form in the non-precipitation regime was identified up to 2.0mol·L−1. The coefficients of thermal expansion values were estimated from measured density data. It was found that, the densities, viscosities and refractive indices of the aqueous sodium glycinate decrease with an increase in temperature, whereas with increasing sodium glycinate concentration in the solution, all three properties increase. Thermal expansion coefficients slightly increase with rising temperature and concentration. The measured values of density, viscosity and refractive index were correlated as a function of temperature by using the least squares method. The predicted data obtained from correlation equations for all measured properties were in fairly good agreement with the experimental data.

Investigation of the suitability of aqueous sodium glycinate as a solvent for post combustion carbon dioxide capture on the basis of pilot plant studies and screening methods

Post combustion CO2 capture (PCC) through reactive absorption is a promising technology to tackle climate change. The application of new solvents enables a reduction in energy demand. This research work discusses the suitability of aqueous sodium glycinate (NaGly) as a CO2 absorption solvent.Laboratory studies show slow absorption kinetics and moderate CO2 absorption capacities of aqueous NaGly. Results from pilot plant tests at the coal-fired power plant in Dürnrohr, Austria, with 15, 25 and 40wt% NaGly are presented and discussed. Realistic industry conditions were achieved through the use of flue gas from the power plant and the well-conceived dimensions of the test facility. Low energy consumption of aqueous NaGly was mainly predicted by simulations in literature (∼3 GJ/tCO2). The measured energy consumption in the present work is much higher (>5 GJ/tCO2). This represents an increase of 40% with respect to 30wt% monoethanolamine (MEA), not combined with enhanced system extensions. The low predicted optimal solvent flow rate could not be confirmed in the present work. The optimal liquid to gas ratio is in the range of 7–8l/m3.

Enthalpies of Absorption of Carbon Dioxide in Aqueous Sodium Glycinate Solutions at Temperatures of (313.15 and 323.15) K

The enthalpies of absorption (ΔrH) of carbon dioxide in aqueous sodium glycinate (SG) solutions of 0.10 in mass fraction were determined at temperatures of (313.15 and 323.15) K and a pressure of 12.00 MPa using an isothermal high-pressure flow calorimeter. Very exothermic absorption enthalpies are obtained at the two temperatures studied. ΔrH values expressed in kJ·mol−1 of SG decrease very quickly as CO2 loading increases until saturation is reached; from this point, a slowly decreasing value is obtained for the absorption enthalpy. CO2 loading is expressed as mol CO2/mol amine (α). The calorimetric data provide a means to determine the saturated loading point of CO2 in the solution; values of (0.90 and 0.86) mol CO2/mol SG were estimated for this magnitude at temperatures of (313.15 and 323.15) K, respectively. Enthalpies of solution of CO2 were also calculated. These enthalpies become more exothermic as α decreases until a limit value characteristic of each amine is observed for low CO2 loading. This ...

Solubilities of Carbon Dioxide and Densities of Aqueous Sodium Glycinate Solutions before and after CO2 Absorption

The densities of aqueous solutions of sodium glycinate (SG) were measured for a range of concentrations [(1, 5, 10, 15, 20, and 30) % wt] and at a temperature range (298.15 to 353.15) K. The solubility of CO2 in aqueous solution of sodium glycinate was measured for the same concentration range and at two temperatures (298.15 and 313.15) K, over CO2 partial pressure ranging from (100 to 2500) kPa. The densities of aqueous solutions of sodium glycinate after the absorption were also measured at the same conditions of the solubility measurements. It was found that density of aqueous solutions of sodium glycinate increases as the molar concentration increases and decreases with an increase in temperature. The solubilities of CO2 are reported as loading capacity (mol CO2/mol SG) as a function of partial pressure of CO2 at the corresponding temperature. It was found that CO2 solubility increases with increase in CO2 partial pressure. It was also found that solubility of sodium glycinate solution decreases with increasing sodium glycinate concentration and temperature. The densities of aqueous sodium glycinate after absorption gave a higher value than that before absorption and increase with increasing pressure.

Simulation of CO2 removal with aqueous sodium glycinate solutions in a pilot plant

In this paper, density, viscosity, surface tension and vapor pressure of aqueous sodium glycinate solutions of different mass fractions (0.1–0.5) at different temperatures (20–100°C) were simulated using Pro/II (version 6.01), a commercial process simulator, and compared with corresponding experimentally measured data. It was found that simulated data of physicochemical properties compared well with corresponding experimental data. We have also predicted concentration of CO2 with each ideal stage in an absorber/stripper tower.

Kinetics of CO2 Absorption in Aqueous Sodium Glycinate Solutions

The physical solubility and diffusivity of N2O and CO2 in aqueous sodium glycinate (SG) solutions of various concentrations (1.0−3.5 kmol/m3) and temperatures (303.15−323.15 K) were reported. The kinetics of the reaction between CO2 and SG has been studied using absorption data measured by a wetted-wall column apparatus at various temperatures and concentrations. The second-order rate constant of CO2 with SG was determined to be k2(m3 kmol-1 s-1) = 1.95 × 1013 exp(−7670/T), where T is the absolute temperature (given in Kelvin). The activation energy for the reaction of CO2 with SG was calculated to be 63.8 kJ/mol.

Density, viscosity, and surface tension of aqueous sodium glycinate solution as an absorbent for carbon dioxide removal

Density, viscosity, and surface tension of aqueous sodium glycinate solution as an absorbent for carbon dioxide removal

Physical Solubility and Diffusivity of N2O and CO2 in Aqueous Sodium Glycinate Solutions

Physical solubility and diffusivity of N2O and CO2 in pure water and of N2O in aqueous sodium glycinate solutions of mass fraction (0.1 to 0.5) were measured at T = (303.15 to 323.15) K. Since it was not possible to measure these properties for CO2 due to the chemical reaction between CO2 and the amine group of sodium glycinate, these were estimated using the well-known N2O analogy. While the physical solubility increases with a decrease in temperature and with a decrease in mass fraction, diffusivity decreases with a decrease in temperature as well as an increase in mass fraction except for concentrated solution (mass fraction 0.4 and 0.5) where it increases with a decrease in temperature.

Physical Properties of Aqueous Sodium Glycinate Solution as an Absorbent for Carbon Dioxide Removal

The physicochemical properties of aqueous sodium glycinate solution such as density, viscosity, surface tension, alkalinity, and pH were measured over a wide range of mass fraction (0.1 to 0.5) of sodium glycinate and at T = (303.15 to 353.15) K. The measured data were correlated with standard equations, and parameters were reported along with average absolute deviations.