Aqueous Potassium Carbonate Solution Research Articles

Solution blow spinning of highly deacetylated chitosan nanofiber scaffolds for dermal wound healing.

Biocompatible fibrous scaffolds based on highly deacetylated chitosan were fabricated using high-throughput solution blow spinning. Scanning electron microscopy analysis revealed that the chitosan nanofiber scaffolds had ultrafine and continuous fibers (300-1200nm) with highly interconnected porous structures (30-75% porosity), mimicking some aspects of the native extracellular matrix in skin tissue. Post-treatment of as-spun nanofibers with aqueous potassium carbonate solution resulted in a fibrous scaffold with a high chitosan content that retained its fibrous structural integrity for cell culture. Analysis of the mechanical properties of the chitosan nanofiber scaffolds in both dry and wet conditions showed that their strength and durability were sufficient for wound dressing applications. Significantly, the wet scaffold underwent remarkable elastic deformation during stretch such that the elongation at break dramatically increased to up to 44% of its original length, showing wavy fiber morphology near the break site. The culture of normal human dermal fibroblast cells onto scaffolds for 1-14days demonstrated that the scaffolds were highly compatible and a suitable platform for cell adhesion, viability, and proliferation. Secretion profiles of wound healing-related proteins to the cell culture medium demonstrated that chitosan fibers were a promising scaffold for wound healing applications. Overall, the dense fibrous network with high porosity of the chitosan nanofiber scaffold and their mechanical properties indicate that they could be used to design and fabricate new materials that mimic the epidermis layer of natural skin.

Integrated Approach of Phytostabilization for Urban Ecosystem Soils Contaminated with Lead

The article discusses the creation of a methodological approach and the specific technologies based on it in terms of the phytostabilization of urban soils contaminated with heavy metals, taking into account the peculiarities of urban ecosystems functioning in order to ensure the environmental safety of industrial wastelands. Based on the analysis of existing soil restoration methods, a mechanism for creating an integrated phytostabilization technology was developed by involving the components differing in action, aimed at reducing the migration ability of heavy metals in soil and their translocation into plants. It was suggested to increase the phytoremediation potential of phytostabilizers through the stimulation of internal defence mechanisms of plants, and through additional application of an ameliorant to bind heavy metal cations in soil, as well as through the use of microbiological preparation in order to restore soil protective functions. The practicability of phytostabilization using alfalfa (Medicago sativa) plants combined with detoxification with an aqueous solution of potassium carbonate and the BTU-r multipurpose biocomplex microbiological preparation was experimentally confirmed by means of an example of lead contamination of urban ecosystem soils in the city of Dnipro. It was concluded that their combination provides the lowest Pb2+ removal from the soil by alfalfa (Medicago sativa) plants and a significant reduction in the availability of the metal compounds in soil.

Removal of barite from zircon using an aqueous solution of diethylenetriaminepentaacetic acid and potassium carbonate

Abstract In most geologic applications, if barite is present, it must be separated from zircon to enable analysis of the zircon. Current methods of barite removal include mechanical comminution in a ball mill or conversion to barium carbonate by boiling in an aqueous solution of sodium carbonate. Both procedures have potentially serious drawbacks. We optimized an alternative technique for barite removal to avoid these shortcomings. In repeated experiments, boiling in an aqueous solution of 0.1 M diethylenetriaminepentaacetic acid (DTPA) and 6 wt% potassium carbonate for one hour dissolved about 90% of sand-size barite grains. Examination of barite after boiling in DTPA solution revealed evidence for attacks on crystal surfaces in the form of microscopic scallops and pits. In contrast, zircon crystal surfaces were not detectably altered at the microscopic scale by a boiling solution of DTPA and potassium carbonate. The DTPA and potassium carbonate solution procedure may be superior to the other two barite removal methods in two ways. First, it might not introduce bias into the sample, in contrast to both of the other two methods. Second, it requires less time than the sodium carbonate solution technique. If future research shows that the DTPA and potassium carbonate solution technique does not affect isotopic systems in zircon, this method appears to be a favorable alternative to both milling and boiling in sodium carbonate solution.

Viscosity of potassium carbonate solutions promoted by new amines

"The objective of this paper is presenting the experimental results of the viscosity measuring for the aqueous solutions of potassium carbonate with new amines as promoters. In this work, ethylenediamine (EDA) and triethylenetetramine (TETA) were chosen as rate promoter candidates. The viscosity of the ternary aqueous solutions (K2CO3-Amine-H2O) has been measured for a blending 25 wt % potassium carbonate, amine concentrations between 1 to 7 wt % for EDA and 1 to 3 % for TETA, at atmospheric pressure and temperatures from 298 K to 343 K."

K2CO3-containing composite sorbents based on a ZrO2 aerogel for reversible CO2 capture from ambient air

Abstract In this work, K2CO3-containing composite materials were synthesized based on a mesoporous zirconia aerogel prepared by an epoxide-assisted sol-gel method using supercritical drying in ethanol. The porous ZrO2 was impregnated with an aqueous solution of potassium carbonate to obtain composite materials with K2CO3 weight content ranging from 9 to 29 wt%. All the composites were tested in the process of CO2 absorption from the air with a relative humidity of 25% followed by thermal desorption at 200 °C. The samples after the CO2 absorption step were characterized by Fourier transform infrared spectroscopy and X-ray diffraction methods. Among the materials studied, the composite sorbent containing 23 wt% K2CO3 demonstrated the highest dynamic CO2 absorption capacity (4.6 wt%) in the temperature-swing absorption (TSA) cycles. The results indicate that a certain part of K2CO3 loaded into zirconia mesopores forms surface species which do not actively participate in the CO2 absorption and desorption processes. For the composite K2CO3/ZrO2 material with the optimal K2CO3 loading, CO2 absorption capacity is higher compared to the values obtained for K2CO3/γ-Al2O3 composite sorbents studied under the same conditions. Taking into account that this material demonstrates stable CO2 absorption capacity values in the consecutive TSA cycles and needs a relatively low temperature for regeneration, it should be considered for application in Direct Air Capture units.

Reducing of UV Radiation Intensity, Ozone Concentration and Fume Formation in Gas Metal Arc Welding

The UV radiation intensity and mass concentration of ozone in air are studied experimentally in the gas metal arc welding. Effects of the shielding gas composition influence on UV radiation intensity, ozone concentration and welding fume formation are demonstrated. Addition of potassium via wetting the electrode wire or work-piece by aqueous solution of potassium carbonate and via its premix with shielding gas leads to decrease of UV radiation and ozone formation during arc welding. Discussions of the observed effects and theoretical model of radiation absorption are presented.

3D printed sandwich materials filled with hydrogels for extremely low heat release rate

Additive manufacturing is a powerful tool to design materials with original properties. An innovative design of poly (Ethylene Vinyl Acetate) (EVA) containing 30 wt.-% of Aluminum TriHydroxide (ATH) was reported in a previous paper and liquids (water or potassium carbonate aqueous solution) were incorporated in the 3D printed structure. These multi-materials showing interesting properties, but stability, control and processing of these liquid-containing systems were an issue due to porosity of the polymeric matrix. To overcome this issue, the use of hydrogels is considered in this study: being either solid or highly viscous, hydrogels can retain water in the design, despite the high porosity of the EVA/ATH matrix. In this paper, the liquid phase was substituted by flame retardant hydrogels (based on agar, alginate or poly (vinyl alcohol) - PVA), containing in particular vermiculite platelets and for the hydrogel based on alginate, K2CO3 as flame retardant fillers. Excellent behavior under a 50 kW/m2 heat flux during a cone calorimeter test was obtained, with fast extinguishment of the flame and a low peak of Heat Release Rate (pHRR) and Total Heat Release (THR). The physical barrier formed by vermiculite platelets during the test, as well as the condensed phase mechanism of K2CO3 were found to be responsible for these excellent results, as found by confocal microscopy observations, electron probe micro analysis and X-Ray diffraction experiments.

Distribution constants and group increments of organic substances in the extraction systems of water saline–hexane

In the extraction systems of hexane–aqueous solutions of potassium carbonate, ammonium sulfate and sodium chloride, the distribution of a number of organic compounds (benzyl alcohol, tetrahydrofuran, phenol, aniline, pyridine, pyridazine, pyrimidine, n-butylamine, diethylamine, triethylamine, benzylamine) was studied. It was shown that sodium chloride, the most frequently used as a salting out agent, is noticeably inferior in salting ability to potassium carbonate, dipotassium phosphate and ammonium sulfate, since it contains singly charged ions with a relatively low charge density. Using the method of group increments on the example of aliphatic alcohols, the salting out ability of a number of mineral salts with singly charged ions was evaluated. By the value of this ability, the salts studied are arranged in the following order: NaNO2 > NaCl > KCl ~ NaBr > NaClO4 > KJ > NH4NO3 > NH4SCN. At the same time, the salting out effect of the last four salts from the above series is small. Based on the usage of the group increment method, the nature of the salting out effect is additionally confirmed, which consists, first of all, in strengthening the structure of the saline solution and increasing the increment of the methylene group (ICH2) with increasing the salt concentration.

Numerical simulation of CO2 / H2S simultaneous removal from natural gas using potassium carbonate aqueous solution in hollow fiber membrane contactor

Abstract The sweetening process of natural gas has an undeniable rule in mitigating the detrimental influences of the toxic / corrosive chemical contaminants as like as CO2 and H2S on industrial units and environment. In this study, a 2D numerical simulation was developed to investigate the CO2 / H2S simultaneous molecular removal from natural gas utilizing K2CO3 aqueous solution circulating through the hollow fiber membrane contactor (HFMC). Simulation results were evaluated versus those of experimentally measured data gathered from the literature and an acceptable agreement was observed, i. e. average absolute relative errors (AAREs) of around 1.2 and 1.5 % in the simulated and the experimentally measured CO2 fluxes versus the liquid and gas phases’ velocities, respectively. Also, the results illustrated that increment in the membrane porosity and module length eventuated in a substantial improvement in the molecular removal of CO2 and H2S while increase in the membrane tortuosity and gas velocity significantly reduced CO2 and H2S removal.

Enhancement of carbon dioxide absorption into aqueous potassium carbonate by adding amino acid salts

Abstract Increasing carbon dioxide emissions in the environment is a universal matter that needs a decisive resolve so as to moderate the developing risk of climate alter. Numerous studies have been conducted over the closing few decades to solve this issue. In this study, aqueous potassium carbonate (K2CO3) solution promoted by amino acid salts were applied for absorbing carbon dioxide from gas mixture in a packed column. The experiments were achieved at atmospheric pressure and working temperature of 298 K using mixed gas consists of 15 vol% of carbon dioxide and 85 vol% nitrogen gas. While, the experiments of desorption were conducted at working temperature of 363 K. The absorption performance of 30 wt% (1 M) K2CO3 solution after adding 10 vol% of different amino acid salts solution [Glutamine salt (Glns), Glutamic acid salt (Glus), Tryptophan salt (Trps), Methionine salt (Mets) and Tyrosine salt (Tyrs)] was evaluated. It was found that adding amino acid salts solution as promoter to K2CO3 solution increases the absorption rate and enhances all other solvent properties.

Thermodynamic modeling of CO2 absorption in aqueous potassium carbonate solution with electrolyte NRTL model

Aqueous potassium carbonate (K2CO3) solution is a favorable choice for CO2 removal due to low costs and lessened environmental impacts compared to amine solutions. To support process development of CO2 removal with aqueous solutions, we present a comprehensive thermodynamic model for the H2O + K2CO3 + CO2 ternary system using electrolyte Nonrandom Two-liquid (eNRTL) activity coefficient model. Experimental data of vapor-liquid equilibrium, heat capacity, excess enthalpy, mean ionic activity coefficient and osmotic coefficient are simultaneously used to determine the temperature dependent eNRTL binary interaction parameters for the ternary system and its binary subsystems. Covering a wide temperature range of 273.15–473.15 K, the K2CO3 concentration up to saturation, and the CO2 loading range of 0–3.6, the model satisfactorily represents all the thermodynamic properties for the system. The model should be a very useful tool in the research, development and design of CO2 capture processes involving concentrated K2CO3 solutions at elevated temperatures and pressures.

Explosion mitigation using aqueous solutions of water and flame inhibitors

The current paper describes results of tests performed with aqueous solutions of flame inhibitors at a larger-scale. Two sets of experiments were performed: experiments using superheated aqueous solutions and experiments where aqueous solutions were dispersed using a water deluge system. The main aim of these experiments was to verify the effects seen on small-scale on a larger scale to verify the possibility of using this mitigation technique on industrial scale. Both sets of experiments were performed in a congested 50m3 chamber provided with explosion venting. To generate water-mists directly at a larger-scale in sufficiently high concentrations a dispersion of superheated aqueous solutions of potassium carbonate seems to be the only viable solution. The application of a water deluge system implies relying on break-up of the large water droplets by the accelerating explosion flame itself.

Hard anodization of copper in potassium carbonate aqueous solution

Anodization of copper was performed in potassium carbonate aqueous solution. Registered current curves allowed to claim that the anodic oxide film growth occurs according to the hard anodization mechanism. Detailed investigation of the anodization products revealed formation of nanowires made of crystalline phases including various oxides and complex phases containing hydroxyl anions and carbonates. It was found that the diameter of the nanowires grows linearly with the anodizing voltage between 30 (10 V) and 47 nm (50 V). The major, crystalline components of the anodically grown nanowires were: paramelaconite (Cu4O3), cuprite (Cu2O) and tenorite (CuO). The presence of malachite, Cu2CO3(OH)2 was also reported and meant effective incorporation of the electrolyte anions into the growing anodic film.

Silica scrubbing from superheated steam using aqueous potassium carbonate solution: An experimental investigation

A study on scrubbing of superheated steam containing silica impurities is performed using an aqueous potassium carbonate solution as a potential application in mitigation of superheated geothermal steam. An experimental setup aimed at testing a silica particle scrubbing technique was built. The setup consists of a superheated steam generating system, a silica particle feeding and an injection system, a salt solution injection and separation system, and a sampling unit. Silica particle concentration, salt solution concentration and superheated steam temperature were determined at the outlet for different injected salt solution concentrations. Results indicate improved scrubbing performance obtained using relatively small amounts of aqueous potassium carbonate solution as compared to that obtained using traditional wet scrubbing, while allowing the superheat to be conserved.

Experimental investigation of CO2 solubility and its absorption rate into promoted aqueous potassium carbonate solutions at elevated temperatures

Aqueous potassium carbonate solutions are suitable for capturing CO2 from flue gases and process gases with a low heat duty for regeneration. However, their absorption rate and capacity can be further improved by promoters. In this study, an experimental investigation of CO2 solubility and absorption rate into pure and promoted potassium carbonate solutions in a batch stirred reactor at elevated temperatures is presented. Measurements for pure K2CO3 solvents were carried out at 80 °C, 100 °C and 120 °C for 1.81 M and 2.53 M potassium carbonate concentrations. Solubility results were successfully validated against electrolyte-NRTL model predictions. The experiments were also used to provide a reference for evaluating the effect of promoter addition on CO2 solubility and absorption rate. Subsequently, four additives, namely Methyl diethanolamine (MDEA), Monoethanolamine (MEA), Piperazine (PZ) and Glycine were tested at various concentrations in a 1.81 M potassium carbonate solution at a temperature range of 100–120 °C. Results indicated an increase in solvent capacity and absorption rate for PZ- and MEA-promoted K2CO3 solutions. Glycine addition benefits the absorption rate mostly at low loadings, although the solvent capacity is not affected positively. MDEA has a detrimental effect on solvent capacity at higher concentrations, while no positive effect on absorption rate was found.

Excellent Crystal Coloration and An Extraordinary Improvements of Developing Synthetic Quartz Single Crystals Growth and Defects

The analysis of the impurity content crystals grown in sodium carbonate solution is carried out using flame technique. Colored crystals have been produced from aqueous solutions of potassium carbonate under laboratory conditions and using a steel autoclave. The seeds were slices cut parallel to the planes (0001). With the impurity of aluminum and irradiation, defective color centers have generated quartz coloration phenomenon. This is occurred on the base of the electrical balance by exchanging aluminum ions with tetravalent silicon ions in the presence of alkali elements (monvalent) i.e. Na+ or Li+ . Interestingly, the current paper introduces a method suggests the utilization of silica-rich rocks to develop the growth of large crystals of synthetic quartz.

Theoretical investigation of carbon dioxide capture by aqueous boric acid solution: A termolecular reaction mechanism

Hitherto, boric is suggested and used as a promoter or catalyst for carbon dioxide capture in various chemical absorption reactions, such as, absorption by aqueous potassium carbonate solution to increase mass transfer rate. But in this study, a single step termolecular reaction mechanism is suggested for the chemical absorption of carbon dioxide directly by boric acid and water. The reaction thermochemistry and reaction kinetics for termolecular mechanism are investigated by using density functional theory calculations at the B3LYP/6-31G(d) level of theory by taking into account of the implicit solvent effects of water through the polarizable continuum model and dispersion corrections. The findings obtained from theoretical calculations indicate that it is possible to capture carbon dioxide with boric acid in the form of B(OH) 2 OCOOH.

Experimental and Theoretical Study of CO2 Absorption with Piperazine-Promoted Potassium Carbonate Solution in Hollow Fiber Membrane Contactors

Potassium carbonate is an economical absorbent for CO2 separation from flue gases. In this study, potassium carbonate as absorbent and piperazine as promoter were applied to absorb CO2 from a gas mixture using a hollow fiber membrane contactor in experimental scale. Also, a mathematical model has been presented to find the CO2 concentration profile in different phases and to analyze the process. Effects of concentration of potassium carbonate and piperazine and other parameters such as liquid and gas flow rates were experimentally observed and studied. Effects of membrane wetting on absorption recovery and piperazine concentration on effective length of the module have been analyzed using the mathematical model. Experimental results show that CO2 recovery can rise up to 1.6 times and CO2 recovery can reach to 90% by adding 0.03 M piperazine to 5 wt % aqueous solution of potassium carbonate. The results of the mathematical model at high gas flow rates reveal that CO2 recoveries are considerably higher (up ...

CO2 absorption using aqueous solution of potassium carbonate: Experimental measurement and thermodynamic modeling

Potassium carbonate solution is a widely used solvent for CO2 removal due to its benefit in energy consumption and other economic concerns like degradation and corrosion problem. In this study, the solubility of CO2 in aqueous solutions of potassium carbonate was measured using pressure-decay method at temperatures of 313.15 K, 323.15 K, and 333.15 K, different pressures (up to 1.2 MPa), and different solution concentrations of 15 %wt., 20 %wt., and 30 %wt. Also, two equations of state were utilized to anticipate CO2 solubility in aqueous solution of potassium carbonate. The model is a combination of chemical equilibrium in the liquid phase and physical equilibrium between the liquid and vapor phases. For vapor-liquid equilibrium calculations, Peng-Robinson equation of state (PR-EOS) was used to present the fugacity coefficient in the vapor phase. The activity coefficient in the liquid phase was presented by Pitzer equation. Also, the values of the primitive interaction coefficients (λCO2,K+ and μCO2,CO2,K+) were optimized using the available literature data of the similar system. The results demonstrated that the performance of the thermodynamic modeling procedure was acceptable and the average absolute relative deviation (AARD) between the experimental and the predicted data was less than 2.7%.

Viability of probiotic Lactobacillus rhamnosus in structured emulsions containing saturated monoglycerides

The influence of structured emulsions containing saturated monoglycerides (MG) on the viability of a probiotic Lactobacillus rhamnosus strain during cold storage for up to 56days was investigated. Six emulsions were prepared, containing sunflower oil or anhydrous milk fat (AMF) as lipid phase, and UHT skim milk or an aqueous solution of potassium bicarbonate or potassium carbonate as water phase, and the probiotic strain. All samples behaved like weak gels, but MG-based emulsion containing AMF show values of storage (G′) and loss (G″) moduli as well as strength significantly higher than those of the samples containing oil. Probiotic strain added as fresh pellet survived the gel preparation procedure regardless the type of MG-based emulsion. During cold storage, bacteria in the MG-based emulsion prepared using skim milk maintained a viability much higher than that of the control and other samples. The proposed approach could offer a way to protect probiotic bacteria and to deliver them into dairy products.