Carbonate Salts Research Articles

Predicting CO2 solubility in aqueous and organic electrolyte solutions with ePC-SAFT advanced

Solvent influence and salt influence on CO2 solubility are essential factors toward the development of processes involving CO2 conversion. In this work, the equation of state (EOS) electrolyte Perturbed-Chain Statistical Associating Fluid Theory (ePC-SAFT advanced) was applied to model the CO2 solubility in single organic solvents (methanol, ethanol, N-methyl-2-pyrrolidone, dimethyl sulfoxide, tetrahydrofuran, dimethylformamide, γ-valerolactone, and acetonitrile). Further, CO2 solubility was predicted in aqueous solvent mixtures and in aqueous electrolyte solutions (NaCl, KCl, CsCl, MgCl2, CaCl2, NaNO3, KNO3, Mg(NO3)2, Ca(NO3)2, Na2SO4, K2SO4, MgSO4, NaHCO3, and K2CO3) with water as single solvent as well as in aqueous alcoholic solvent mixtures. CO2 solubility in systems with a lack of data (CsCl) was measured in this work with a high-pressure variable-volume view cell. Broad ranges of temperatures, pressures, and high concentrations of electrolytes were considered, and solvent effects, ion effects, and pH effects were studied. The nature of the considered systems required including dissociation reactions of carbonic acid in the modeling framework, most importantly for the systems containing carbonate salts. The results showed that i) CO2 solubility was the highest in non-polar solvents, ii) all salts caused salting-out effects on the CO2 solubility except carbonates (an apparent salting-in due to a pH shift), and that iii) the strength of salting-out effect was related to the charge density of the ions. The salt influence on CO2 solubility was predicted qualitatively correct with ePC-SAFT advanced; that is, fitting binary interaction parameters between ions and CO2 was not necessary, which is a result found for the first time. Finally, ePC-SAFT advanced allowed predicting the CO2 solubility in multi-component systems containing solvent mixtures, salt mixtures, or a solvent mixture with an additional salt over a broad range of conditions in good agreement with available literature data.

Corrosion Evaluation of Austenitic and Duplex Stainless Steels in Molten Carbonate Salts at 600 °C for Thermal Energy Storage

Next-generation concentrated solar power (CSP) plants are required to operate at temperatures as high as possible to reach a better energy efficiency. This means significant challenges for the construction materials in terms of corrosion resistance, among others. In the present work, the corrosion behavior in a molten eutectic ternary Li2CO3-Na2CO3-K2CO3 mixture at 600 °C was studied for three stainless steels: an austenitic grade AISI 301LN (SS301) and two duplex grades, namely 2205 (DS2205) and 2507 (DS2507). Corrosion tests combined with complementary microscopy, microanalysis and mechanical characterization techniques were employed to determine the corrosion kinetics of the steels and the oxide scales formed on the surface. The results showed that all three materials exhibited a corrosion kinetics close to a parabolic law, and their corrosion rates increased in the following order: DS2507 < SS301 < DS2205. The analyses of the oxide scales evidenced an arranged multilayer system with LiFeO2, LiCrO2, FeCr2O4 and NiO as the main compounds. While the Ni-rich inner layer of the scales presented a good adhesion to the metallic substrate, the outer layer formed by LiFeO2 exhibited a higher concentration of porosity and voids. Both the Cr and Ni contents at the inner layer and the defects at the outer layer were crucial for the corrosion resistance for each steel. Among the studied materials, super duplex stainless steel 2507 is found to be the most promising alternative for thermal energy storage of those structural components for CSP plants.

Duplex Stainless Steels for Thermal Energy Storage: Characterization of Oxide Scales Formed in Carbonate Salts at 500 °C

Next generation concentrated solar power (CSP) plants promise a higher operating temperature and better efficiency. However, new issues related to the corrosion against protection of the construction alloys need to be solved. In this work, two different duplex stainless steels grades, namely 2205 (DS2205) and 2507 (DS2507), were evaluated for their compatibility with the eutectic molten salt mixture of Li2CO3-K2CO3-Na2CO3 at 500 °C in air for thermal energy storage applications. Corrosion tests combined with complementary microscopy, microanalysis and mechanical techniques were employed to study the oxide scales formed on the surface of the duplex steels. The corrosion tests evidenced that the attack morphology in both duplex steels was a uniform oxidative process without localized corrosion. DS2507 presented a better corrosion resistance than DS2205, due to the formation of thinner, compact and continuous oxide layers with higher compositional content in Cr, Ni and Mo than DS2205. The oxide scales of DS2507 showed more remarkable mechanical integrity and adhesion to the metallic substrate.

Nutrient-doped synthetic silicates for enhanced weathering, remineralization and fertilization on agricultural lands of global cold regions- A perspective on the research ahead.

There is now a dire demand for negative emissions technologies (which sequester CO2 from the atmosphere) that can be rapidly deployed, are scalable, and are demonstrably safe and effective. Enhanced weathering of silicate minerals has demonstrated a significant potential for CO2 capture and sequestration by the formation of pedogenic carbonates in soils, subsoils, and sediments. This technique has also been shown to deliver fruitful results in terms of improving soil health, and in turn plant health, through remineralization. The silicate minerals that possess the highest weathering rates (e.g., wollastonite), are relatively rare in nature, whereas the abundant ones (e.g., anorthite and forsterite) have a slower pace of weathering, especially in colder and drier climates such as found in the extensive agricultural lands of Western Canada and the Western United States. Herein, we offer a perspective on the opportunities for computational studies targeting atomic-scale interaction of CO2 with silicates and synthesis of fast-weathering silicates (such as larnite and bredigite), whose composition can be tuned to also support soil fertilization and remineralization, and whose production must be integrated with green and carbon-neutral technologies to ensure net-negative life cycle emissions.

Experimental investigation of iron removal from wet phosphoric acid through chemical precipitation process

In the present work, the combination of experimental investigation and statistical analysis has been used for the first time to study iron precipitation from wet-process phosphoric acid. Firstly, eight types of additives including different carbonate and hydroxide salts were studied in the chemical precipitation reaction in order to decrease the iron content in wet-process phosphoric acid. From different studied reagents, calcium carbonate and calcium hydroxide showed the best to remove ferric ions from crude wet-phosphoric acid. Under the optimum conditions, about 80% and 83% of the iron can be removed at 70 ℃ after the addition of calcium carbonate and calcium hydroxide, respectively. The maximum P2O5 losses from crude phosphoric acid was less than 4% after the addition of calcium hydroxide. Based on the Arrhenius behavior, the activation energy of iron precipitation was calculated about 47.43 and 51.55 kJ/mol for calcium carbonate and calcium hydroxide addition, respectively. The iron state studies showed that the pretreatment process was unnecessary to reduce iron state from ferric to ferrous form before precipitation. Furthermore, the kinetics parameters showed that the iron precipitation process was an endothermic reaction. The XRD analysis of the precipitates produced confirmed the formation of Fe(OH)3, α-Fe2O3, α-FeOOH and FeCO3 through the reaction of iron with carbonate and hydroxide ions. Possible pathways of iron precipitation were proposed. Both calcium carbonate and calcium hydroxide showed good efficiency to remove iron from wet-process phosphoric acid accompanied by moderate P2O5 losses. The Taguchi technique was applied to optimize the parameters using signal-to-noise ratio analysis as well as ANOVA. The analysis showed a greater susceptibility of the response against changes in the value of calcium carbonate, more than calcium hydroxide.

A low-cost eco-friendly fast drug extraction (FaDEx) technique for environmental and bio-monitoring of psychoactive drug in urban water and sports-persons’ urine samples

Nicotine is the most prominent psychoactive/addictive chemical substance consumed worldwide among young players in team sports. Moreover, urinary nicotine discharge and nicotine-based products disposal in environmental waters has been unavoidable in recent years. Therefore, sensitive monitoring of nicotine content in environmental waters and human urine samples is essential. In this study, we developed a miniaturized novel green, low-cost, sensitive, in-syringe-based semi-automated fast drug extraction (FaDEx) protocol coupled with gas chromatography-flame ionization detection (GC-FID) for the efficient environmental and bio-monitoring of nicotine in aqueous samples. The FaDEx method consists of two steps; firstly, the target analyte was extracted using dimethyl carbonate (a green solvent) and extraction salts. After that, the extraction solvent was passed automatically through the solid-phase extraction cartridge at a constant flow rate for the cleanup process to achieve the sensitive nicotine analysis by GC-FID. Under optimized experimental conditions, the developed method showed excellent linearity over the concentration ranges between 20–2000 ng mL−1 with a correlation coefficient >0.99. The detection and quantification limits were 4 and 20 ng mL−1, respectively. The presented method was applied to monitor and assess nicotine exposure in sports-persons’ urine and environmental water samples. The method accuracy and precision in terms of relative recovery and relative standard deviation (for triplicate analysis) were 85.4–110.2% and ≤8%, respectively. Finally, the impact of our procedure on the environment from a green analytical chemistry view was assessed using a novel metric system called AGREE, and obtained the greenness score of 0.87, indicating its an efficient alternative green analytical protocol for routine environmental and bio-monitoring of nicotine in environmental and biological samples.

Encapsulated salts in velvet worm slime drive its hardening

Slime expelled by velvet worms entraps prey insects within seconds in a hardened biopolymer network that matches the mechanical strength of industrial polymers. While the mechanic stimuli-responsive nature and building blocks of the polymerization are known, it is still unclear how the velvet worms’ slime hardens so fast. Here, we investigated the slime for the first time, not only after, but also before expulsion. Further, we investigated the slime’s micro- and nanostructures in-depth. Besides the previously reported protein nanoglobules, carbohydrates, and lipids, we discovered abundant encapsulated phosphate and carbonate salts. We also detected CO2 bubbles during the hardening of the slime. These findings, along with further observations, suggest that the encapsulated salts in expelled slime rapidly dissolve and neutralize in a baking-powder-like reaction, which seems to accelerate the drying of the slime. The proteins’ conformation and aggregation are thus influenced by shear stress and the salts’ neutralization reaction, increasing the slime’s pH and ionic strength. These insights into the drying process of the velvet worm’s slime demonstrate how naturally evolved polymerizations can unwind in seconds, and could inspire new polymers that are stimuli-responsive or fast-drying under ambient conditions.

Laser-induced carbonization of stainless steel as a corrosion mitigation strategy for high-temperature molten salts applications

New heat transfer fluids are necessary to shift the operation temperature of concentrating solar power plants (CSP) to higher temperatures. Ternary carbonate salts (Li2CO3-K2CO3-Na2CO3) are a promising candidate. However, higher temperature translates to harsher operating conditions for CSP structural components as corrosion is more prevalent. In this work, we explore, for the first time, the use of laser micro-machining technology as a surface modification method to inhibit corrosion of CSP structural materials by molten salts. The corrosion behaviour of SS310 in molten ternary carbonate salt is investigated through static immersion for 600 h. Nanosecond laser treatment results in the adhesion of organic groups in the form of hydrocarbons. These then decompose into carbon and contribute to corrosion inhibition through carbonization and the formation of carbide layers. This is confirmed by the reduced diffusion of Li + ions in the SS310, the formation of denser corrosion products and the protection of chromium oxide layers.

Thermal decomposition and oxidation of cation exchange resins with and without Na2CO3–K2CO3 salt

Owing to the capability of trapping sulfur and reducing the formation of sulfur bridges, the addition of carbonate salt is one of the ideal destruction technologies for the treatment of cation exchange resins (CERs). The oxidation processes of CERs with and without Na 2 CO 3 –K 2 CO 3 salt were investigated using TG, FT-IR and XPS. The results of these analyses indicate that in addition to the evaporation process, the oxidation process of CERs can be described as: during the thermal decomposition of the sulfonic acid groups, there are direct destruction of functional groups and the dehydration of functional groups. In addition to the destruction of styrene-divinylbenzene copolymer, the continuous oxidation process includes the direct thermal decomposition of sulfonyl bridges and the formation of sulfur bridges, which decompose at high temperature. The elemental analysis results confirmed that the presence of carbonate salt reduced the formation of sulfur bridges in residue. The SO 2 can be effectively adsorbed by carbonate salt to form sulfate in the salt. Moreover, the content of sulfate ions in waste salt were determined by ICP-MS, which proves that oxidation with Na 2 CO 3 –K 2 CO 3 at 550 °C for 1 h is the optimal oxidation condition to form the sulfate in carbonate salt. • The Na 2 CO 3 –K 2 CO 3 salt can effectively promote the oxidation of resins. • Carbonates can convert the sulfur bridge structure in residue into sulfate. • Four oxidation processes of resin are described by quantifying S content.

Effects of prenatal exposure to PM2.5 and its composition on cognitive and motor functions in children at 12 months of age: The Shanghai Birth Cohort Study

BackgroundPrenatal fine particulate matter (PM2.5) exposure has been linked to infant cognitive and motor functions, but the effects of PM2.5 chemical composition remain unclear. ObjectivesWe aimed to explore the associations of prenatal PM2.5 and its composition exposure with infant cognitive and motor functions. MethodsWe studied 2,435 mother-infant pairs in the Shanghai Birth Cohort Study. PM2.5 and its seven compositions [primary particles (black carbon, mineral dust and sea salts) and secondary particles (NH4+, NO3–, SO42- and organic matter)] during thethreetrimesters ofpregnancy were retrieved from the V4.CH.03 product developed by using a combined geoscience-statistical method. At the 12-month-old follow-up, infant cognitive and motor functions in five domains were assessed using the Ages and Stages Questionnaire (ASQ). We used multivariable linear regressions to estimate the effects of PM2.5 and its composition on the ASQ scores, for all infants and stratifying by sex and breastfeeding duration. ResultsPM2.5 exposure was negatively associated with gross motor, problem-solving and personal-social scores for all infants. PM2.5 compositions were inversely associated with ASQ scores in all five domains, and the effects of different compositions varied across domains. Specifically, all compositions except organic matter were correlated with lower problem-solving scores [e.g., (βSO42- = − 10.79, 95 % CI: −17.40, −4.18) ∼ (βNO3- = − 4.68, 95 % CI: −7.84, −1.53); for each 10 μg/m3 increase in PM2.5 compositions during the third trimester]. Primary and some secondary particles (organic matter, NO3–) were related to lower gross motor scores. Secondary particles were also inversely associated with communication (organic matter and NO3–), fine motor (NH4+, NO3–, SO42-) and personal-social (NH4+) scores. Additionally, boys and infants breastfed for < 6 months appeared to be more susceptible. ConclusionsWe found negative associations of PM2.5 and its compositions with infant cognitive and motor functions over a range of domains, especially the problem-solving domain.

Manganese Promoted (Bi)carbonate Hydrogenation and Formate Dehydrogenation: Toward a Circular Carbon and Hydrogen Economy.

We report here a feasible hydrogen storage and release process by interconversion of readily available (bi)carbonate and formate salts in the presence of naturally occurring α-amino acids. These transformations are of interest for the concept of a circular carbon economy. The use of inorganic carbonate salts for hydrogen storage and release is also described for the first time. Hydrogenation of these substrates proceeds with high formate yields in the presence of specific manganese pincer catalysts and glutamic acid. Based on this, cyclic hydrogen storage and release processes with carbonate salts succeed with good H2 yields.

Novel textured surfaces for superior corrosion mitigation in molten carbonate salts for concentrating solar power

Corrosion of metals in contact with molten salts used for thermal energy storage and heat transport at high temperatures is a serious impediment to the development of next-generation concentrating solar thermal systems. Toward addressing this limitation, novel multiscale fractal-textured Ni coatings on a variety of substrate alloys are presented in this study for exceptional corrosion mitigation in molten carbonate salts at a high temperature. Strongly adherent, durable, single-layer, and double-layer multiscale fractal coatings were fabricated using the electrodeposition method. Corrosion performance of the coatings on SS310, SS316, SS347, and In800H was studied in molten carbonate salt (32% Li2CO3+33% Na2CO3+35% K2CO3) at 750 °C. Single-layer coatings are stable up to 300 h immersion, whereas double-layer coatings are stable beyond 750 h. The corrosion rate of double-layer Ni coatings on ferrous alloys was reduced by as much as 60% from that of uncoated surfaces and was about 18% below that of higher cost, high Ni content Ha230. The study represents the first-ever report of corrosion characteristics of alloys in carbonate salts at 750 °C and the first demonstration of a means of dramatically reducing corrosion in carbonate salts at a high temperature. The article is significant in that it provides a viable approach for low-cost structural alloys to be corrosion-resistant to molten carbonate heat transfer fluids and storage media in high-temperature concentrating solar thermal applications. The corrosion-resistant coatings provide opportunities for the use of low-cost, ferritic alloys instead of the expensive nickel-based alloys in practice.

Ligand Elucidation of Dissolved Transition Metal Ions in Pristine and Degraded Electrolytes in Li-Ion Batteries

During operation of a Li-ion battery, layered transition metal oxides release metal ions into the electrolyte. In addition to capacity loss, dissolved metal ions are mobile in the electrolyte and can deposit at the anode, enhancing Faradaic losses and posing the risk of dendrite formation.[1] In the electrolyte solution, transition metal ions are characterized mainly by their oxidation state and complexation behavior, which dictate the transport through the electrolyte. Additionally, mechanistic insights, indirect information about electrolyte degradation, and design of counter-measures might be extracted thereof. However, particularly the coordination sphere is difficult to access, due to inherently low concentrations and scarcity of suitable analytics.In this work, the coordination sphere of dissolved transition metal ions is selectively probed by pulse Electron Paramagnetic Resonance (pEPR). pEPR selectively addresses isolated paramagnetic ions, masking analytical interference from other species in the battery. Because of its known impact on capacity fade, firstly Mn2+ is analyzed in premixed pristine and degraded electrolyte solutions. Carbonates with high dielectric constants such as ethylene carbonate (EC) are the dominant ligands, accompanied by electrolyte salt anions for charge compensation. If present, trace amounts of electrolyte degradation products such as fluorophosphates selectively form the first coordination sphere. The results from pEPR measurements, that have to be performed on frozen solutions at cryogenic temperatures, agree with paramagnetic NMR results at ambient temperatures. Furthermore, samples from batteries operating with vanadium-based cathodes were investigated. Depending on the storage conditions, V4+ ligands predominantly consist of decomposition products from the electrolyte solvent ethylene carbonate (e.g. ethylene glycol anions) or electrolyte salt LiPF6 (fluorophosphates).[2,3] [1] C. Zhan, T. Wu, J. Lu, K. Amine, Energy Environ. Sci. 2018, 11, 243–257.[2] C. Szczuka, R.-A. Eichel, J. Granwehr, ACS Appl. Energy Mater. 2022, 5, 449–460.[3] C. Szczuka, P. Jakes, R.-A. Eichel, J. Granwehr, Adv. Energy Sustain. Res. 2021, 2, 2100121.

How Does Carbon Dioxide-Induced Acidification Affect Postecdysial Exoskeletal Mineralization in the Blue Crab (Callinectes sapidus)?

Carbon dioxide (CO2 ) enrichment in seawater because of increased use of fossil fuels can possibly cause detrimental effects on the physiological processes of marine life, especially shell builders, due to CO2 -induced ocean acidification. We investigated, for the first time, specifically the effect of CO2 enrichment on postecdysial shell mineralization in Crustacea using the blue crab, Callinectes sapidus, as the model crustacean. It was hypothesized that CO2 enrichment of seawater would adversely affect exoskeletal mineralization in the blue crab. We used two groups of postecdysial crabs, with one group exposed to seawater at a pH of 8.20 and the other group treated with CO2 -acidified seawater with a pH of 7.80-7.90. After a period of 7 days, samples of exoskeleton and hemolymph were collected from the survivors. Enrichment was found to significantly increase exoskeletal magnesium content by 104% relative to control, whereas a statistically nonsignificant elevation of 31% in exoskeletal calcium was registered. Because CO2 treatment did not change the content of magnesium and calcium in the hemolymph, we postulate that increased exoskeletal mineralization in postecdysial blue crabs must stem from an increased influx of bicarbonate ions from the medium through the gill, to the hemolymph, and across the epidermis. In addition, the observed significant increase in the mass of exoskeleton following CO2 treatment must be at least partly accounted for by enhanced postmolt carbonate salt deposition to the shell. Environ Toxicol Chem 2022;41:2950-2954. © 2022 SETAC.

Comparison of immediate and sustained release formulations of lithium salts

Lithium salts are widely used clinically, mainly for treatment of bipolar disorder, in which it is highly effective. Various preparations have been developed and tested, including older immediate-release (IR) forms of lithium carbonate and other salts and formulations with slow-release (SR) properties, developed in hopes of increasing the tolerability of lithium treatment, adherence to its use, and possibly its efficacy. Systematic reviews of head-to-head comparisons of pharmacological and clinical properties of such preparations are lacking. Accordingly, we systematically reviewed clinical studies of both IR and SR formulations of lithium salts, seeking to compare their pharmacokinetic properties, adverse effects, clinical tolerability, and clinical effectiveness. Very few such comparative studies were identified and they are highly heterogeneous in design and findings. In 11 included reports, SR formulations appeared to be better tolerated and possibly to be associated with greater adherence to treatment. Studies of comparative clinical efficacy are lacking. Despite decades of use of various lithium salts, systematic comparisons of the pharmacological and clinical properties of IR vs. SR preparations remain rare and to be deepened, though with suggestive superiority of SR salts.

A soybean sodium/hydrogen exchanger GmNHX6 confers plant alkaline salt tolerance by regulating Na+/K+ homeostasis.

Alkaline soil has a high pH due to carbonate salts and usually causes more detrimental effects on crop growth than saline soil. Sodium hydrogen exchangers (NHXs) are pivotal regulators of cellular Na+/K+ and pH homeostasis, which is essential for salt tolerance; however, their role in alkaline salt tolerance is largely unknown. Therefore, in this study, we investigated the function of a soybean NHX gene, GmNHX6, in plant response to alkaline salt stress. GmNHX6 encodes a Golgi-localized sodium/hydrogen exchanger, and its transcript abundance is more upregulated in alkaline salt tolerant soybean variety in response to NaHCO3 stress. Ectopic expression of GmNHX6 in Arabidopsis enhanced alkaline salt tolerance by maintaining high K+ content and low Na+/K+ ratio. Overexpression of GmNHX6 also improved soybean tolerance to alkaline salt stress. A single nucleotide polymorphism in the promoter region of NHX6 is associated with the alkaline salt tolerance in soybean germplasm. A superior promoter of GmNHX6 was isolated from an alkaline salt tolerant soybean variety, which showed stronger activity than the promoter from an alkaline salt sensitive soybean variety in response to alkali stress, by luciferase transient expression assays. Our results suggested soybean NHX6 gene plays an important role in plant tolerance to alkaline salt stress.

Insights into the Enhancement Mechanisms of Molten Salt Nanofluids

The addition of nanomaterials to molten salts can significantly improve their thermal performance. To explore the enhancement mechanisms, this work prepared carbonate salt nanofluids with binary carbonate as base salt and 20 nm SiO2 and 20 nm MgO nanoparticles as additives by the commonly used aqueous solution method. Then, the key performance and micromorphology of the carbonate salt nanofluids are characterized by differential scanning calorimetry, thermal gravimetric analysis, laser flash analysis, and micromorphology analysis. Results showed that the 20 nm SiO2 nanomaterials instead of the 20 nm MgO nanomaterials exerted higher effects on latent heat while the 20 nm MgO nanomaterials instead of the 20 nm SiO2 nanomaterials exerted higher effects on the sensible heat, thermal conductivity, and high-temperature stability of carbonated salt. In addition, different nanostructures were observed in SiO2-based and MgO-based molten salt nanofluids, respectively. Innovatively, formation mechanisms of molten salt nanofluids were proposed based on cloud nuclei to explain the different enhancements in this work.

Stochastic-Fractal Analysis Modeling of Salts Precipitation from Aqueous Solution

Electrolytes are of interest because thin plate coatings are normally obtained from aqueous solutions. The properties of the surface are important because various properties such as resistance or durability depend on it. To understand the phenomenological processes, it is better to analyze simpler processes such as sodium chloride. In this paper, a model is proposed to predict the temporal behavior of the fractal dimension of the patterns formed in salts precipitation by solvent evaporation in a scattering surface; for fractal-box counting, ImageJ software was used. The model was obtained by applying stochastic methods and fractal geometry, describing the internal fluctuations caused by precipitation and dissolution on the mesoscopic scale of solid crystalline particles. From adjusting the proposed model to the experimental data, it is possible to estimate the velocity constants related to the microscopic precipitation processes of the particles that form the pattern. The model was validated and used to study the precipitation of carbonate salts and sodium chloride, respectively, obtaining predictions corresponding to the physicochemical properties of these salts. From the adjustment of the proposed models to the observed experimental data, the value of the velocity constants of the precipitation and dissolution processes was also estimated.

The application of an enhanced salinity-gradient solar pond with nucleation matrix in lithium extraction from Zabuye salt lake in Tibet

The utilization of salinity-gradient solar ponds (SGSPs) to extract lithium from salt lake brine is one of the most direct and effective uses of solar energy. The Qinghai-Tibet Plateau in China is rich in unique solar energy resources, as well as various types of salt lakes with abundant lithium resources. Among them, Zabuye salt lake in Tibet is a typical lithium-rich carbonate salt lake, and it has successfully realized the industrialization of lithium extraction from brine for the first time by using the SGSP. In recent years, with the continuous improvement of lithium resource market, the demand for lithium has further grown. There are some bottleneck problems restricting the lithium carbonate production in the lithium extraction technology with traditional SGSPs, which must be overcome, such as the slower heating rate, smaller heating amplitude, longer production cycle, lower crystallization efficiency and so on. From the angle of green environmental protection and high-efficiency technology, this research focused on the temperature field and salinity field distribution of the traditional SGSP and the special crystallization behavior of lithium carbonate, and carried out experimental research on process optimization in Zabuye mining area. Based on the heterogeneous nucleation theory, the use of an enhanced SGSP with a nucleation matrix for assisting the crystallization of lithium carbonate was proposed. The change of crystallization behavior of lithium carbonate, the influence of matrix materials and the spatial distribution on the crystallization effect were investigated. The results show that the enhanced SGSP with the nucleation matrix has a significant effect of increasing the production of lithium carbonate, and the lithium mixed salt attached to the nucleation matrix is of a higher grade and a lower moisture content. The yield per unit area of lithium carbonate on the nucleation matrix made of the gauze and plastic net is equivalent to that on the slope and bottom of the solar pond, and the grade of lithium carbonate approaches 80 %. The yield per unit area of lithium carbonate on the nucleation matrix made of tumbleweed is about four times as much as is achieved with other materials and the crystallization exceeds expectations. It is concluded that the application of the enhanced SGSP with the nucleation matrix can improve the crystallization efficiency, the output and the grade of lithium carbonate to a certain extent and this optimization technique will provide an important theoretical basis and application support for green, efficient development of lithium resources from salt lake brine.

A Mars orbital catalog of aqueous alteration signatures (MOCAAS)

We describe the completion of the MOCAAS project providing a global repository of secondary minerals formed through interaction with water on Mars. This work is based on the analysis of orbital imaging spectroscopy data from the OMEGA/Mars Express and CRISM/MRO near-infrared instruments. A database and a set of high-resolution global maps (200 m/pix) are produced which provide a large collection of these “aqueous” secondary mineral deposits, most of which were not previously reported. Several aqueous mineral classes are discriminated including hydrated silicates, hydrated silica, sulfate and carbonate salts. A preliminary statistical analysis on the database of aqueous mineral deposits is carried out, revealing significantly more widespread and diverse aqueous alteration on Noachian and Hesperian Mars than previously seen. Higher resolution local scale studies are also carried out over current and prospective rover landing sites on Mars, providing enhanced sensitivity to mineral detection and reachable science targets. Collectively, the data presented here at all scales is expected to foster synergy between orbital and landed missions, particularly for future missions and to pinpoint prospective resources for human exploration.