Sodium Carbonate Solution Research Articles

Carbonation of Sodium Aluminate/Sodium Carbonate Solutions for Precipitation of Alumina Hydrates—Avoiding Dawsonite Formation

Experimental work has been performed to investigate the precipitation mechanism of aluminum hydroxide phases from sodium aluminate/sodium carbonate pregnant solutions by carbon dioxide gas purging. Such solutions result from leaching calcium aluminate slags with sodium carbonate solutions, in accordance with the Pedersen process, which is an alternative process for alumina production. The concentration of carbonate ions in the pregnant solution is revealed as a key factor in controlling the nature of the precipitating phase. Synthetic aluminate solutions of varying sodium carbonate concentrations, ranging from 20 to 160 g/L, were carbonated, and the resulting precipitating phases were characterized by X-ray diffraction analysis. Based on the results of the previous carbonation tests, a series of experiments were performed in which the duration of carbonation and the aging period of the precipitates varied. For this work, a synthetic aluminate solution containing 20 g/L free Na2CO3 was used. The precipitates were characterized with X-ray diffraction analysis and Fourier-transform infrared spectroscopy.

Efficient recovery of U(VI) from strongly alkaline solution using nanoscale zero-valent iron

Although nanoscale zero-valent iron (nZVI) has been intensively investigated for the remediation of uranium contaminated water, few efforts have been dedicated to U(VI) removal and recovery by nZVI from strongly alkaline solutions (e.g., pH 10.7) in the presence of carbonate. This work demonstrates that U(VI) can be removed by nZVI from strongly alkaline solutions in the anaerobic atmosphere. Results show that reductive precipitation is responsible for U(VI) removal with an effective reduction efficiency of nZVI up to 95.5 ± 3.3% (6.09 ± 0.21 g of U/g of Fe). In the aerobic atmosphere, however, the efficiency is no more than 8.3% (0.53 g of U/ g of Fe) due to relatively rapid corrosion reactions of nZVI as well as the re-oxidation of U(IV). The difference in the efficiency originates not only from the variation in the kinetics of corrosion reactions, but also from U(VI) redox and coordinate chemistry. Under the aerobic condition, uranium removal reaches the maximum at 1 h of reaction and then decreases, because uranium delivery from solid phase occurs due to successive processes of U(IV) oxidation, UO22+ complexation with carbonate, and [UO2(CO3)3]4- desorption from surfaces. The uranium delivery limits the application of nZVI for uranium removal under the aerobic condition, but provides a candidate approach for the uranium recovery from the spent nZVI. A recovery of 100% can be obtained by sodium carbonate solution in the presence of O2. Both the oxidation and desorption processes control the uranium recovery rate. This study not only offers new insight into the mechanisms of interactions between U(VI) and nZVI especially in strongly alkaline media with high concentration of carbonate, but also provides a reference approach to the issue of U(VI) removal and recover from the wastewater generated in the nuclear industry.

Exogenous healing in concrete with pH-sustained internal carbonation

In this study, experimental investigations were conducted on enhancing the crack-healing potential of concrete using the internal carbonation process. The objective is to overcome one major limitation of autogenous healing (limited carbonation) by using Sodium Carbonate (Na2CO3) solution as a healing agent. To replicate the different types of damages and internal cracking that could arise during the service life of concrete structures, the effects of drying shrinkage and mechanical stresses on the crack-healing proclivity of cement-based materials were explored. A novel technique to measure crack-healing under constantly applied stress is also introduced for better assessment of healing in real-world situations. Results show a significant improvement in healing by using 0.95 M Na2CO3 solution over plain water. Moreover, permeability observations under stress revealed that the potential for healing by the proposed mechanism is strongly dependant on the stress level in samples. In the later part of the paper, Service Life Predictions were also undertaken by utilizing chloride ion diffusion coefficients extracted from the measured permeability coefficients and service life models available in the literature. Results from comparison of predicted service life indicate that at least in qualitative terms, healing with internal carbonation using the Na2CO3 solution led to an increase in the service life of concrete composites.

Preparation of nano-sized calcium carbonate in solution mixing process

Discreet nano-sized precipitated calcium carbonate was prepared by a simple solution mixing process, in which sodium carbonate solution was injected into calcium chloride solution containing calcium hydroxide. The morphology, size, and structure of the as-prepared precipitated calcium carbonate and intermediate products were examined. The results indicated that the non-impurity additive of calcium hydroxide, temperature below 30 °C, and controlled injecting rate were essential to obtain nano-sized precipitated calcium carbonate in the solution mixing process. It was observed that the intermediate nanofibrils fragged into nanograins in the process. This method can provide a simpler method to study the formation mechanism of nano calcium carbonate.

CO2-induced carbonate minerals as soil stabilizing agents for dust suppression

This study aims to introduce alternative environmentally friendly compositions for soil-dust suppression. Carbon dioxide was utilized to produce free carbonate (CO 3 2– ) by a laboratory electrolysis cell. Different carbonate mineral compositions were then provided by adding Fe 2+ , Mg 2+ , and Ca 2+ ions to the sodium carbonate solution. Different carbonate minerals were eventually used as soil stabilizing agents for sandy soil-dust suppression. Laboratory tests including unconfined compressive strength (UCS), direct shear test, California bearing ratio (CBR), and permeability tests in addition to field tests were performed to assess the feasibility of using CO 2 induced carbonate minerals as soil stabilizing agent. It was found that the UCS and cohesion intercept of the treated specimens increased in comparison with the untreated specimens. CBR rating of the treated specimens indicated a harder surface which resulted in a lower permeability of the treated specimens. The study showed this alternative approach is a promising effort in utilization of CO 2 for soil surface stability improvement.

Controlling Calcium Carbonate Particle Morphology, Size, and Molecular Order Using Silicate

Calcium carbonate (CaCO3) is one of the most abundant substances on earth and has a large array of industrial applications. Considerable research has been conducted in an effort to synthesize calcium carbonate microparticles with controllable and specific morphologies and sizes. CaCO3 produced by a precipitation reaction of calcium nitrate and sodium carbonate solution was found to have high polymorphism and batch to batch variability. In this study, we investigated the polymorphism of the precipitated material and analyzed the chemical composition, particle morphology, and crystalline state revealing that the presence of silicon atoms in the precipitant is a key factor effecting particle shape and crystal state. An elemental analysis of single particles within a polymorphic sample, using energy-dispersive X-ray spectroscopy (EDS) conjugated microscopy, showed that only spherical particles, but not irregular shaped one, contained traces of silicon atoms. In agreement, silicon-containing additives lead to homogenous, amorphous nanosphere particles, verified by X-ray powder diffraction (XRD). Our findings provide important insights into the mechanism of calcium carbonate synthesis, as well as introducing a method to control the precipitants at the micro-scale for many diverse applications.

Laterally-resolved formation mechanism of a lithium-based conversion layer at the matrix and intermetallic particles in aerospace aluminium alloys

Lithium leaching coatings have recently been developed as eco-friendly active corrosion protection technology for aerospace aluminium alloys (AAs) by the formation of a conversion layer at coating defects. While general conversion layer formation characteristics were studied and reported before, here we study the local layer formation process with sub-micron resolution at and around intermetallic particles (IMPs) in AA2024-T3. Top- and cross-sectional-view morphological electron micrograph observations along with open circuit potential (OCP) measurements are performed, mimicking coating defect conditions upon lithium carbonate leaching from the coating matrix. The results revealed five stages of the conversion process in which the alloy matrix and different IMPs evolve morphologically, compositionally, and electrochemically. Besides, we found a correlation between the OCP response of the AA2024-T3 system and the morphological and compositional evolutions of the alloy matrix and IMPs at different stages of exposure. Passive layer and alloy matrix dissolution leading to surface Cu-enrichment and S-phase dealloying occur at early stages of exposure. They precede the formation of a columnar layer on the alloy, followed by the establishment of a dense-like layer at the final stage. Dealloying of Al2CuMg can assist the conversion process by providing local supersaturation. Through complementary experiments in a sodium carbonate solution and besides X-ray diffraction analysis, we found out that lithium plays a critical role in stabilising the corrosion product throughout the conversion process.

Laboratory Study on Improvement of Expansive Soil by Chemically Induced Calcium Carbonate Precipitation

This paper proposes the use of calcium carbonate (CaCO3) precipitation induced by the addition of calcium chloride (CaCl2) and sodium carbonate (Na2CO3) solutions as a procedure to stabilize and improve expansive soil. A set of laboratory tests, including the free swell test, unloaded swelling ratio test, unconfined compression test, direct shear test, scanning electron microscopy (SEM) test, cyclic wetting–drying test and laboratory-scale precipitation model test, were performed under various curing periods to evaluate the performance of the CaCO3 stabilization. It is concluded from the free swell tests and unloaded swelling ratio tests that the addition of CaCl2 and Na2CO3 can profoundly decrease soil expansion potential. The reduction in expansion parameters is primarily attributed to the strong short-term reactions between clay and stabilizers. In addition, the formed cementation precipitation can decrease the water adsorption capacity of the clay surface and then consequently reduce the expansion potential. The results of unconfined compression tests and direct shear strength tests indicated that the addition of CaCl2 and Na2CO3 has a major effect on geotechnical behavior of expansive soils. Based on the SEM analyses, new cementing crystalline phases formatted by sequentially mixing CaCl2 and Na2CO3 solutions into expansive soil were found to appear in the pore space, which results in a much denser microstructure. A laboratory-scale model test was conducted, and results demonstrate the effectiveness of the CaCO3 precipitation technique in stabilizing the expansive soil procedure. The test results indicated that the concentration of CaCl2 higher than 22.0% and Na2CO3 higher than 21.2% are needed to satisfactorily stabilize expansive soil. It is proposed to implement the precipitation technique in the field by the sequential permeation of CaCl2 and Na2CO3 solutions into soils in situ.

Experiments on two techniques for the removal of barite from detrital zircon

Abstract Barite (BaSO4) is a common mineral in sandstone that must be removed during separation of detrital zircon (ZrSiO4). One widespread technique for the removal of barite exploits its lesser tenacity by milling the barite and zircon mixture in a ball mill. Here we test the extent to which such milling affects zircon and thus whether the milling could introduce bias into the detrital zircon sample. We then describe a new chemical technique for the removal of barite from detrital zircon. We find that milling a mixture of barite and zircon both breaks and causes loss of zircon grains, potentially introducing bias into a detrital zircon sample. Boiling barite in a 0.94 molar aqueous solution of sodium carbonate for 4 h converts most grains to barium carbonate. The barium carbonate grains are opaque white and thus visually distinguishable from zircon, allowing separation by hand under a stereoscopic microscope. Alternatively, the barium carbonate grains can be dissolved by boiling in 16 wt% nitric acid for 30 min. In our experiments, boiling zircon in sodium carbonate solution and/or concentrated (65 wt%) nitric acid cleaned the surfaces of and the cracks in the grains but did not visibly change the zircon surfaces in other ways. Boiling only in concentrated nitric acid did not measurably affect the U-Pb and Lu-Hf isotopic systems in zircon interiors, and boiling in a sodium carbonate solution followed by concentrated nitric acid did not detectably alter the Lu-Hf isotopic system. However, boiling in a concentrated sodium carbonate solution followed by concentrated nitric acid did disturb the U-Pb isotopic system in zircon interiors. We recognize this disturbance due to a ~0.5% reduction in 206Pb/238U dates of treated zircon. Our results highlight the importance of proper technique during zircon isolation to minimize the introduction of bias into the sample.

Tuning the extraction mechanism of uranyl ion in bicyclooctanium, propylpyridinium, piperidinium and imidazolium based ionic liquids: First ever evidence of 'cation exchange', 'anion exchange' and 'solvation' mechanism

A novel diamide ligand, 5-bromo-N1, N3-diisopropylisophthalamide has been synthesized and characterized by FTIR, 1H NMR, and 13C NMR. The extraction mechanism of uranyl ion with the diamide ligand has been studied in unexplored ionic liquid families. For the same metal–ligand system; cation exchange, anion exchange, and solvation mechanism can be predominately achieved by changing the ionic liquid system. The experimental results suggest that the change in extraction mechanism is induced by the cations of the ionic liquids. In bicyclooctanium ionic liquid, the extracted species was [UO2(NO3)3L2]-; In piperidinium and pyridinium-based ionic liquid, the species were UO2(NO3)2L and UO2(NO3)2L2 respectively. In imidazolium-based ionic liquid, the species was [UO2(NO3)L]+. Though the extraction efficiency in methylpyridinium and bicyclooctanium based ionic liquids are better, the pipiredinium and imidazolium-based ionic liquids exhibited a high degree of radiological stability. The aqueous solution of sodium carbonate is found to be better in the back extraction of uranyl ions from the ionic liquids relative to EDTA and oxalic acid. However, the efficacy of back extraction differs largely on the ionic liquid system.

OBTAINING HIGH QUALITY LITHIUM CARBONATE FROM NATURAL LITHIUM-CONTAINING BRINES

The aim of this work is to develop a new effective technology for producing high-quality lithium carbonate from natural lithium-containing brines. Freshly deposited aluminum hydroxide was used to separate lithium from the trace amounts of sodium and calcium. It was found that the completeness of lithium extraction from brines purified from magnesium depends on the sorbent dosage, phase contact time, mineralization, pH, and brine temperature. To extract lithium from brines with a mineralization of less than 100 g/dm3, it is necessary to introduce 4 mol of aluminum hydroxide per 1 mol of lithium in the brine. For brines with a mineralization greater than 200 g/dm3, the consumption of the sorbent providing the extraction of lithium more than 96% is 2.5 mol of aluminum hydroxide. Desorption of lithium chloride from lithium-aluminum concentrate is carried out by processing 4-5 canopies of concentrate in a Soxlet type apparatus with the same volume of distilled water. The resulting concentrated solution of lithium chloride is purified from calcium impurities in contact with a saturated solution of lithium carbonate. From a heated aqueous solution of lithium chloride purified from calcium impurities, lithium carbonate is precipitated by dosing a stoichiometric amount of a saturated solution of sodium carbonate into it. The precipitate of lithium carbonate is separated from the mother solution, washed with three portions of a saturated solution of lithium carbonate at a ratio of solid to liquid by weight equal to one to five, in order of decreasing the concentration of sodium in each portion of the wash water. The dried product contains at least 99.6% Li2CO3.

Influence of temperature and light on total phenolic compounds during natural orange juice storage

Introduction Natural orange juice is a phenolic compounds rich beverage, whose disposal on market and food catering has increased with the expansion of the concept of healthy food, raising concerns about the effect of storage on total antioxidant capacity (TAC), and scientific evidence on this is scarce. Regarding TAC, is well established that phenolic compounds account more to it than ascorbic acid [1]. Our aim was to evaluate the concentration of total phenolic compounds (CTPC) in fresh squeezed orange juice and analyse the influence of storage conditions (temperature and light) during 48 h on CTPC. Materials and methods Fresh oranges (Citrus sinensis, variety “Valencia Late”, Portugal) of the same calibre and producer were squeezed aliquoted into 3 glasses stored in different conditions: (1) Room temperature (20 °C) and exposed to sunlight; (2) Room temperature (20 °C) fully wrapped in aluminium; and (3) Refrigerated (1 °C). The procedure was performed according to the methodology described by Keskin-Šašić et al. [2]. CTPC was quantified by Folin-Ciocalteu spectrophotometric method, using gallic acid as standard, at 0, 2.5, 4, 8 and 48 h. (a) Samples preparation: 1 mL of orange juice was diluted from each vial in water, to a volume of 25 mL. Part of solution was centrifuged at 5300 rpm for 20’. The supernatant solution was used to analyse. (b) Determination of CTPC: approximately 0.2 mL of each sample was transferred to test tubes containing 1.0 mL of a dilution of Folin–Ciocalteu reagent in water (1:10). After 10’, 0.8 mL of a sodium carbonate solution (7.5% m/v) was added to the sample. The test tubes were allowed to stand at room temperature for 30’, and then absorbance was measure at 743 nm. CTPC was expressed as equivalents of gallic acid (EGA) in mg/100 ml of squeezed orange juice. Samples’ CTPC was determined from a standard curve of gallic acid varying between 0.2 and 4 mg/L. Results CTPC of recently squeezed fresh oranges was 30.1 mg EGA/100 mL (basal). After 48 h, CTPC decreased in all samples: 38.5% in sample 1 (18.5 mg EGA/100 mL), 28.6% in sample 2 (21.8 mg EGA/100 mL), and 27.6% in sample 3 (21.5 mg EGA/100 mL). The higher variation in CTPC occurred for sample 1, stored at room temperature and exposed to sunlight. Discussion and conclusions: Our results suggest that exposure to sunlight is the variable that most influences the decrease CTPC of the fresh orange juice after 48 h. More studies on the influence of these variables are needed to confirm these results and to increase knowledge about storage of fruit fresh juices, to ensure the nutritional quality of this product. Squeezed orange juice is widely present on markets and coffee shops, usually refrigerated but not protected from sunlight, which means that the storage conditions would need to be reconsidered.

Carbon-negative biomethane fuel production: Integrating anaerobic digestion with algae-assisted biogas purification and hydrothermal carbonisation of digestate

This paper presents a new integrated process for producing carbon-negative biomethane fuel which combines anaerobic digestion of sewage sludge with biogas purification, algae generation and carbon capture. Biogas CO2 is recovered through absorption into sodium carbonate solution, producing bicarbonate, subsequently used as substrate for algae growth. Anaerobic digestate is hydrothermally carbonised into biochar, stabilising unused biomass carbon for long-term storage.Proof-of-concept studies are provided, together with a system carbon balance to demonstrate its overall carbon capture potential. D. tertiolecta (CCAP 19/30) was cultivated at different bicarbonate concentrations (2.5–90 g L−1), producing equimolar amounts of carbonate and carbon-derived products (algae, gaseous CO2). Above 40 g L−1, carbonate regeneration significantly exceeded algae growth, achieving higher than expected CO2 uptake potential, but lower overall carbon sequestration potential due to the discharge of excess CO2 to the environment. Single-stage CO2 absorption from a model biogas mixture (60% methane) into carbonate solution was rate limited by the reaction of dissolved CO2 with solution hydroxide ions, achieving steady state methane outlet purities of up to 85%. Spent absorbent was successfully used for algae culture, and the regenerated medium showed equivalent CO2 uptake as the fresh carbonate solution, demonstrating the cyclability of the system. Carbon distribution to biochar and algae by-products was estimated as 35.1%, exceeding the expected emissions associated with the process, to render the process carbon negative.

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.

The possibility of using aluminosilicate composite materials after modification and processing in sunflower oil

The paper presents the study results of the isotherms of nitrogen adsorption-desorption on blue and green powdered clays before and after the surface is modified with solutions of organic acids (oxalic, succinic) and sodium carbonate. Unlike powder of natural blue clay, the material of green clay is characterized by the presence of macropores (5%) with a diameter of more than 50 nm; 95% of volume is occupied by mesopores ranging in size 4-40 nm. According to the size distribution data, the total number of mesopores of blue and green clays has reduced after treatment with oxalic acid; it changes slightly after introduction of alkaline compound into system (sodium carbonate, 10 wt %). It was revealed that the process of adsorption of total impurity ingredients of fatty acid triglycerides provides the possibility of using acid-modified clays with a set of properties (specific surface area, pore distribution) after processing for 1 hour in sunflower oil to stabilize the digestive function of the gastrointestinal tract of poultry and improve the quality of eggs laid by them by daily evening introduction into the feed (1-3 wt %) for 1 month prior to laying.

Composition for rock grouting based on insoluble calcium salts for groundwater protection

Importance to reduce permeability of rocks arises safety of mining operations and protecting the soil and underground water in the area of industrial waste storage with high contents of water-soluble salts. Disadvantage of the existing methods of grouting rocks by soluble salts is either their dissolution with changing of the composition or diluting of the contacting solution. The paper considers the composition of the grouting mixture for the deposition of insoluble calcium salts and its effectiveness in laboratory conditions. The eutonic solution of a four-component KCl–NaCl–CaCl2–H2O system was used as the initial solution, while saturated solutions of sodium sulfate and carbonate, and sulfuric acid were applied as the precipitators. Efficiency of rock grouting was estimated according to the water or solution filtration rate through the rock (sand, sylvinite, and halite) before and after calcium salt crystallization. Laboratory experiments showed that the precipitation of calcium sulfate responds to the challenge of plugging rocks. The paper proposes some recommendations of protective screens at the bed of the salt tailing piles and slurry storage facilities.

Study of the kinetics of calcium molybdate leaching with sodium carbonate solutions

Calcium molybdate forms powellite, it is produced as a result of oxidizing roasting of off-grade molybdenum sulphide concentrates and other molybdenum materials with calcium additives (calcium oxides and hydro xides, calcium chlorides) in air at the temperatures of 550–600 oC. Use of Na2CO3 solutions enables an efficient recovery of Мо from CaMoO4 and a quantitative removal of impurities. To determine the optimum conditions for this process, one would need data on CaMoO4 leaching within a broad range of Na2CO3 concentrations and at high temperature and one would need to analyze the composition of the solid phase and the kinetic parameters of the process, i.e. rate and rate-controlling step. The authors look at the CaMoO4 leaching kinetics in 1.0–2.5 mol/l Na2CO3 solutions at 60–90 oC. It was found that the process rate is dictated by the stirring intensity and tends to increase with a rising temperature and the reagent concentration rising in the range of 1.0–1.5 mol/l. A higher concentration of Na2CO3 has no effect on the reaction rate. An apparent reaction order was determined in the Na2CO3 concentration range of 1.0–1.5 mol/l. An equation is proposed for calculating the CaMoO4 dissolution rate for the Na2CO3 solution and the temperature of 80 oC. It was established that a kinetic mode of leaching takes place in the soda concentration range of 1.0–1.5 mol/l amid intensive stirring. It is demonstrated that, within the studied Na2CO3 concentration range, calcite СаСО3 is formed after vaterite, a less stable phase of calcite, with crystallization of double sodium-calcium carbonates Na2Са(CO3)2·nH2O (n = 0, 2, 5) occurring at the same time. With the concentration of soda being >1.5 mol/l, the process is controlled by internal diffusion. In this region, the leaching rate is independent of the Na2CO3 concentration. Formation of double carbonates is associated with an additional consumption of soda. Therefore, when using this system one should consider how CaMoO4 typically dissolves in Na2CO3 solutions. The presence of these compounds in the soda solution after molybdenum leaching may impact the recovery of Мо from the solution using the known techniques. It may also hinder the recirculation of sodium carbonates going for the second leaching cycle.

Uptake and Removal of Uranium by and from Human Teeth.

Uranium-238 (238U), a long-lived radiometal, is widespread in the environment because of both naturally occurring processes and anthropogenic processes. The ingestion or inhalation of large amounts of U is a major threat to humans, and its toxicity is considered mostly chemical rather than radiological. Therefore, a way to remove uranium ingested by humans from uranium-contaminated water or from the air is critically needed. This study investigated the uranium uptake by hydroxyapatite (HAP), a compound found in human bone and teeth. The uptake of U by teeth is a result of U transport as dissolved uranyl (UO22+) in contaminated water, and U adsorption has been linked to delays in both tooth eruption and development. In this present work, the influence of pH, contact time, initial U concentration, and buffer solution on the uptake and removal of U in synthetic HAP was investigated and modeled. The influence of pH (pH of human saliva, 6.7-7.4) on the uptake of uranyl was negligible. Furthermore, the kinetics were extremely fast; in one second of exposure, 98% of uranyl was uptaken by HAP. The uptake followed pseudo-second-order kinetics and a Freundlich isotherm model. A 0.2 M sodium carbonate solution removed all the uranyl from HAP after 1 h. Another series of in vitro tests were performed with real teeth as targets. We found that, for a 50 mg/L U in PBS solution adjusted to physiological pH, ∼35% of the uranyl was uptaken by the tooth after 1 h, following pseudo-first-order kinetics. Among several washing solutions tested, a commercially available carbonate, as well as a commercially available fluoride solution, enabled removal of all the uranyl taken up by the teeth.

Molecular Dynamic Regulation of Na and Mg Ions on Lithium Carbonate Crystallisation in Salt Lakes

Lithium carbonate (Li2CO3) was synthesised by adding sodium (Na) and magnesium (Mg) ions into a lithium chloride solution at different concentrations, followed by the addition of an appropriate sodium carbonate solution. Then, the morphology, purity and particle size of Li2CO3 crystals were investigated. The Na and Mg ions had negligible and remarkable effects, respectively, on the product purity; however they both greatly influenced its morphology. Their effects on the nucleation and growth rates, the radial distribution function and the diffusion behaviour of the synthesised Li2CO3 were investigated via molecular dynamics methods; the Na ions slowed down the crystal nucleation and growth rates, while the Mg ions accelerated them. Moreover, the Mg ions rendered the system short-range ordered and long-range disordered and also increased the diffusion coefficient. The results of this study showed that Mg ions are one of the most important factors influencing the purity and yield of Li2CO3.

A new spring barley variety ‘In Memory of Dudin’

The purpose of the research is to conduct a comprehensive assessment of the new spring barley variety ‘in Memory of Dudin’ on economically valuable signs. Studies were carried out in 2016-2019. The spring barley variety “in Memory of Dudin’ was created by the method of directional individual selection from the variant with treatment of spring barley variety ‘Bios 1’ with laser red light (wavelength 632.8 nm, continuous irradiation mode, beam power density 0.3 mW/cm2) for 60 minutes, followed by soaking in a solution of sodium carbonate with a concentration of 0,1n for 12 hours. Ear of the plant has average length 8.9 cm, the number of spikelets and the grain in the ear are medium (25.6 pcs. and 24.3 pcs. respectively). The 1000-grain weight is high - 49.2 g. Culm has an average length of 72.4 cm. The average yield over the years of the study was 4.6 tons/ha, the maximum one - 7.02 tons/ha in 2019. Dry matter ash content 2.2%, fiber content 3.65%, starch content 52.61%, fat content 1.65%, protein content 10.19%; extractability 77.0%. The variety ripens 4-7 days earlier than the standard. Based on a comprehensive assessment, the spring barley variety of “in Memory of Dudin’ was transferred to the State Variety Test in 2020.