Sodium Glycinate Solution Research Articles

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.

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%).

Proof of concept: Integrated membrane distillation-forward osmosis approaches water production in a low-temperature CO2 capture

This study investigated the removal of CO 2 from flue gas by an integrated membrane distillation-forward osmosis (MD–FO) system. Monoethanolamine (MEA) and sodium glycinate solutions were loaded with CO 2 from a mixture of CO 2 and N 2 (1:9 in volume ratio) to simulate synthetic flue gas. CO 2 desorption from the amine solution was evaluated using MD at 80 °C. Interaction between amines and the membrane polymeric matrix could alter the membrane surface hydrophobicity; however, under all experimental conditions it was still sufficiently hydrophobic for MD operation. Amine loss during MD operation for CO 2 desorption was insignificant. FO was used to provide make-up water and cooling to the regenerated amine solution after CO 2 desorption by MD. The results showed stable FO water flux when wastewater effluent was used as the source for make-up water. Repetitive CO 2 loading and desorption experiments showed 87.0% and 88.1% CO 2 re-absorption efficiency for MEA and sodium glycinate in the second cycle, respectively. Further investigation of this hybrid system is suggested to advance the CO 2 desorption by MD process and water production by FO process. • MD–FO to capture CO 2 from simulated flue gas was demonstrated. • CO 2 was desorbed from monoethanolamine or sodium glycinate without amine loss. • FO provided cooling make-up water from effluent with stable permeate flux. • About 90% CO 2 re-adsorption efficiency was achieved in the 2 nd cycle.

The Cleaning of Silver Objects With a Basic Solution of Sodium Glycinate: A Study on Artificially and Naturally Tarnished Silver

ABSTRACT The appearance of silver objects deteriorates due to the formation of a brown-to-black tarnish layer. Several methods are available for removing these tarnished layers, ranging from polishing through chemical cleaning to electrochemical methods. This study presents a low-cost and low-toxicity method that uses sodium glycinate to clean silver. Cleaning tests were performed on both artificially tarnished prototypes and naturally tarnished objects after characterizing them; scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX) were used to characterize the artificially tarnished prototypes, and X-ray fluorescence (XRF) was used to characterize the naturally tarnished objects. The aggressiveness of the baths was analyzed by measuring the leached amount obtained through atomic absorption spectroscopy (AAS) and SEM. The procedures used for cleaning the artificially tarnished prototypes served as a guide for cleaning two naturally tarnished objects: a halo and a crown. Cleaning was guided by the presented method’s characteristics as well as the object’s unique characteristics and condition.

Optimization in the Absorption and Desorption of CO2 Using Sodium Glycinate Solution

This study used sodium glycinate as an absorbent to absorb CO2 in the bubble column scrubber under constant pH and temperature environments to obtain the operating range, CO2 loading, and mass transfer coefficient. For efficient experimentation, the Taguchi method is used for the experimental design. The process parameters are the pH, gas flow rate (Qg), liquid temperature (T), and absorbent concentration (CL). The effects of the parameters on the absorption efficiency, absorption rate, overall mass transfer coefficient, gas–liquid molar flow rate ratio, CO2 loading, and absorption factor are to be explored. The optimum operating conditions and the order of parameter importance are obtained using the signal/noise (S/N) ratio analysis, and the optimum operating conditions are further verified. The verification of the optimum values was also carried out. The order of parameter importance is pH &gt; CL &gt; Qg &gt; T. Evidence in the 13CNMR (Carbon 13 Nuclear Magnetic Resonance) spectra shows that the pH value has an effect on the solution composition, which affects both the absorption efficiency and mass transfer coefficient. There are 18 experiments for regeneration, where the operating temperature is 100–120 °C. The heat of regeneration was measured according to the thermodynamic data. The CO2 loading, the overall mass transfer, and the heats of regeneration correlation are also discussed in this work. Finally, an operating policy for the CO2 absorption process was confirmed.

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.

Water production through CO2 capture in coal‐fired power plants

AbstractA novel integrated liquid absorbent‐based CO2 capture and desalination process is proposed. It is based on the use of a forward osmosis operation replacing the trim cooler in the capture process. This cooler controls the absorption liquid inlet temperature to the absorber. In the forward osmosis operation water is transferred from a saline solution to the absorption liquid. It can be recovered in two ways: via the overhead condenser of the desorber or via an intercooling operation by flashing the absorption liquid under vacuum, followed by condensation of the water vapor produced. In both cases the energy requirement for the water production process is considered negligible as it is part of the energy requirement of the capture process. The amount of produced water and its quality is such that it can be used as makeup for flue gas desulphurization and/or cooling tower makeup. Thus, it can provide a resolution for the increase in specific cooling water requirement as a result of a CO2 capture retrofit to an existing coal‐fired power station. Monoethanolamine and sodium glycinate solutions were evaluated as absorption liquids in this study. Amino acid salt solutions are preferred because of the high osmotic pressure and low vapor pressure, providing the best option for high water quality.

CO2 capture with aqueous solution of sodium glycinate: Modeling using an ensemble method

As a type of amino acid salt, sodium glycinate (SG) is introduced as a potential solvent for CO2 capture from gas streams like sour natural gas and flue gas. Modeling and assessment of the experimental data of CO2 loading capacity of SG aqueous solution are the main objectives of the present study. To this end, a well-known ensemble method namely the Adaptive Boosting (AdaBoost) technique was utilized in conjunction with the Classification and Regression Tree (CART) algorithm for modeling the CO2 solubility in SG solution as a function of the temperature of the system, CO2 partial pressure, and concentration of SG in the aqueous phase. Then, the Leverage method was employed for investigating the range of applicability of the developed model and quality of the collected experimental data. Furthermore, the AdaBoost-CART was compared to multilayer artificial neural network (MLP-ANN) and least squares support vector machine (LSSVM). It was found that the presented AdaBoost-CART model provides more accurate predictions and has a wide range of applicability. Furthermore, the results suggest that among all the gathered data, six experimental equilibrium CO2 solubility in SG solution are probable outliers.

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.

Performance of a hybrid solvent of amino acid and ionic liquid for CO2 capture

Advanced solvents are under development to reduce the energy consumption for CO2 capture from the coal-fired power plant. In this work, an amino acid, sodium glycinate (SG), and an ionic liquid, [Bmim][BF4], were blended to be used as solvent for CO2 capture. The parametric tests such as blending mole ratio, temperature, CO2 partial pressure and oxygen concentration were investigated. Results revealed the highest CO2 absorption rate was achieved when the blending mole ratio of SG and [Bmim][BF4] was 4:1. Compared with the pure SG solution, the CO2 absorption rate into those blends was 40% higher than that into the pure SG solution under the same tested conditions. The high temperature and CO2 partial pressure facilitated the CO2 absorption. Overall, the blends of SG and [Bmim][BF4] possessing a high CO2 absorption rate, good anti-oxidation ability, and good regeneration efficiency may be an alternative of the MEA solution for CO2 capture.

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%.

Removal of brownish-black tarnish on silver–copper alloy objects with sodium glycinate

This article has the principal aim of presenting a new method of chemical cleaning of tarnished silver–copper alloy objects. The chemical cleaning must be harmless to the health, selective to tarnish removal, and easy to use. Sodium glycinate was selected for the study. The reactions of sodium glycinate with tarnish and the silver–copper alloy were evaluated. Products of the reaction, the lixiviated material, and the esthetics of silver–copper alloy coins (used as prototypes) were studied to evaluate if the proposed method can be applied to the cleaning of silver objects.Silver–copper alloys can be deteriorated through a uniform and superficial corrosion process that produces brownish-black tarnish. This tarnish alters the esthetic of the object. The cleaning of artistic and archeological objects requires more caution than regular cleaning, and it must take into account the procedures for the conservation and restoration of cultural heritage. There are different methods for cleaning silver–copper alloy objects, chemical cleaning is one of them. We studied two chemical cleaning methods that use sodium glycinate and sodium acetylglycinate solutions. Silver–copper alloy coins were artificially corroded in a basic thiourea solution and immersed in solutions of sodium glycinate and sodium acetylglycinate. After immersion, optical microscopy and scanning electron microscopy of the surfaces were studied. The sodium glycinate solution was shown to be very efficient in removing the brownish-black tarnish. Absorption spectroscopy measured the percentage of silver and copper lixiviated in immersion baths, and very small quantities of these metals were detected. Infrared absorption spectroscopy and X-ray fluorescence characterized the obtained products. The greater efficiency of the sodium glycinate solution compared to the sodium acetylglycinate solution was explained by chelation and Hard–Soft Acid–Base Theory with the aid of quantum chemical calculations.

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.

Simplified Estimation of Regeneration Energy of 30 wt % Sodium Glycinate Solution for Carbon Dioxide Absorption

A simple method for estimating the regeneration energy of CO2 absorption was devised. The regeneration energy of a 30 wt % sodium glycinate (SG) solution was calculated by the summation of the enthalpy of reaction, the sensible heat and the heat of vaporization. Each form of heat energy was determined experimentally. Solubilities of carbon dioxide in the SG solution was determined by gas chromatography (GC) analysis for the gas phase with the help of a virial equation for the liquid phase in the temperature range of 40−120 °C. Heat capacity of the solution was measured by a differential scanning calorimeter (DSC) and was used to calculate sensible heat. The heat of vaporization was evaluated by applying the Clausius−Clapeyron equation to 20 data points of vapor pressure. All of the experiments were carried out with either a 30 wt % aqueous solution of SG or the same concentration of monoethanolamine (MEA). Regeneration energy of the SG solution was found to be higher than that of the MEA solution by about 1000 kJ/kg of CO2. From the CO2 solubility data it was observed that SG had a higher capacity to absorb carbon dioxide than MEA even at the regeneration temperature (120 °C). In addition, the 30 wt % basis SG demonstrated a reduction in cyclic capacity at this regeneration temperature. So, our main effort is to establish a reasonable method for estimating CO2 absorbent regeneration energy along with the regeneration energy of 30 wt % aqueous solutions of SG.

Absorption of Carbon Dioxide into Aqueous Solution of Sodium Glycinate

Carbon dioxide was absorbed into aqueous solution of sodium glycinate (SG) at different SG concentrations, CO2 partial pressures, and temperatures in the range of 0.5–3.0 kmol/m3, 25–101.3 kPa, and 298–318 K, respectively, using a stirred semi-batch vessel with a planar gas-liquid interface. Both the reaction order and rate constant are determined from gas absorption rates under the fast reaction regime. The reaction was found to be first order with respect to both CO2 and SG. The activation energy for the CO2-SG reaction has been found to be 59.8 kJ/mol. The second-order reaction rate constants were used to obtain the theoretical values of absorption rate based on the film theory.

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.