Solubility Of Species Research Articles

Anion-π Type Aggregation-Induced Emission Luminogens.

As a type of important non-covalent interactions that can efficiently prohibit π-π interaction to avoid quenching of luminescence, anion-π interactions are receiving growing attention for the fabrication of aggregation-induced emission luminogens (AIEgens) since 2017. The obtained anion-π type AIEgens can be applied in the fields of wash-free bioimaging and long-term tracking of subcellular organelle, photodynamic anti-cancer and anti-bacterial therapy due to their good water solubility, superior photostability and excellent reactive oxygen species generation ability. Moreover, anion-π type AIEgens were also further constructed for room temperature phosphorescence by taking advantages of the heavy-atom participated anion-π interactions. This concept article provides a brief summary of this field, mainly focusing on the design strategy, photophysical properties and applications of anion-π type AIEgens.

Bioactive Platinum(IV) Complexes Incorporating Halogenated Phenylacetates.

A new series of cytotoxic platinum(IV) complexes (1–8) incorporating halogenated phenylacetic acid derivatives (4-chlorophenylacetic acid, 4-fluorophenylacetic acid, 4-bromophenylacetic acid and 4-iodophenylacetic acid) were synthesised and characterised using spectroscopic and spectrometric techniques. Complexes 1–8 were assessed on a panel of cell lines including HT29 colon, U87 glioblastoma, MCF-7 breast, A2780 ovarian, H460 lung, A431 skin, Du145 prostate, BE2-C neuroblastoma, SJ-G2 glioblastoma, MIA pancreas, the ADDP-resistant ovarian variant, and the non-tumour-derived MCF10A breast line. The in vitro cytotoxicity results confirmed the superior biological activity of the studied complexes, especially those containing 4-fluorophenylacetic acid and 4-bromophenylacetic acid ligands, namely 4 and 6, eliciting an average GI50 value of 20 nM over the range of cell lines tested. In the Du145 prostate cell line, 4 exhibited the highest degree of potency amongst the derivatives, displaying a GI50 value of 0.7 nM, which makes it 1700-fold more potent than cisplatin (1200 nM) and nearly 7-fold more potent than our lead complex, 56MESS (4.6 nM) in this cell line. Notably, in the ADDP-resistant ovarian variant cell line, 4 (6 nM) was found to be almost 4700-fold more potent than cisplatin. Reduction reaction experiments were also undertaken, along with studies aimed at determining the complexes’ solubility, stability, lipophilicity, and reactive oxygen species production.

Synthetic antibacterial minerals: harnessing a natural geochemical reaction to combat antibiotic resistance

The overuse of antibiotics in clinical and livestock settings is accelerating the selection of multidrug resistant bacterial pathogens. Antibiotic resistant bacteria result in increased mortality and financial strain on the health care and livestock industry. The development of new antibiotics has stalled, and novel strategies are needed as we enter the age of antibiotic resistance. Certain naturally occurring clays have been shown to have antimicrobial properties and kill antibiotic resistant bacteria. Harnessing the activity of compounds within these clays that harbor antibiotic properties offers new therapeutic opportunities for fighting the potentially devastating effects of the post antibiotic era. However, natural samples are highly heterogenous and exhibit variable antibacterial effectiveness, therefore synthesizing minerals of high purity with reproducible antibacterial activity is needed. Here we describe for the first time synthetic smectite clay minerals and Fe-sulfide microspheres that reproduce the geochemical antibacterial properties observed in natural occurring clays. We show that these mineral formulations are effective at killing the ESKAPE pathogens (Enterococcus sp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter sp., Pseudomonas aeruginosa and Enterobacter sp.) by maintaining Fe2+ solubility and reactive oxygen species (ROS) production while buffering solution pH, unlike the application of metals alone. Our results represent the first step in utilizing a geochemical process to treat antibiotic resistant topical or gastrointestinal infections in the age of antibiotic resistance.

Developing a water chemistry model in the CO2-mixed salts-H2O system to predict the corrosion of carbon steel in supercritical CO2-containing formation water

In this work, a water chemistry model was developed by combining the activity coefficient-fugacity coefficient type solubility model and species equilibrium model to determine the mutual solubilities of CO2 and H2O, and the corresponding species concentrations in the CO2-mixed salts-H2O system (mainly contains Na+, Ca2+, Mg2+, K+, Cl-, and SO42-) with the temperature range of 15–250 °C, the pressure range of 1–600 bar and the salt molality range of 0–6 mol/kg. The computed solubilities of CO2 and H2O, and pH values show a good agreement with the experimental data in the literature, which indicates the high accuracy and accessibility of this water chemistry model. Based on this accurate water chemistry model, a comprehensive mechanistic model was established to predict the corrosion of carbon steel in supercritical CO2-containing formation water based on finite element method. The modeling corrosion rate agrees well with the measured corrosion rate.

High-temperature thermodynamics of ZnO–NH4Cl–H2O system

On the basis of the principles of simultaneous equilibrium, conservation of mass, and aqueous electronic charge neutrality and the correspondence principle of ion entropy, the high-temperature thermodynamics of the ZnO–NH4Cl–H2O system was studied to predict solubility and construct Zn species distribution. The model was constructed precisely by using the MATLAB program. The total Zn2+ concentration in the solution was affected significantly by temperature and total ammonium concentration. ZnNH3Cl3− was the predominant species in the ZnO–NH4Cl–H2O system. The solubility of zinc diammine chloride in NH4Cl solution (>2 mol·L−1) in the temperature range of 303–353 K was determined using equilibrium experiments, which had results that agreed well with the theoretical value. The data and high-temperature thermodynamic model used in this paper are reliable.

Highly efficient phototheranostics of macrophage-engulfed Gram-positive bacteria using a NIR luminogen with aggregation-induced emission characteristics

Although phagocytosis serves as the front line to attack invading pathogens, its low bacterial encounter and killing rates leads to an ineffective bactericidal output. In view of this, developing multifunctional theranostic probe to effectively discriminate and ablate intracellular bacteria is highly desirable. However, the shielding effect of the host macrophages put the detection and elimination of macrophage-engulfed bacteria into a challenging task. Herein, we utilize a luminogen with aggregation-induced emission (AIE) characteristics, namely TTVP, as a simple and effective probe for simultaneous tracing and photodynamic killing of intracellular Gram-positive bacteria. With the help of the AIE property, excellent water solubility, near-infrared (NIR) emission and strong reactive oxygen species (ROS) generating ability, TTVP performed ideally to be a targeting agent to intracellular Gram-positive bacteria with high signal contrast, as well as to be a photosensitizer to effectively ablate intracellular bacteria without attacking host macrophages. This work thus provides insights for the next generation antibiosis theranostic application for potential clinical trials.

Physical properties of chemically deposited ZnS thin films: Role of the solubility curves and species distribution diagrams

A physicochemical analysis was carried out on the chemically deposited ZnS/glass thin films. Solutions were prepared by considering the better chemical conditions obtained from the solubility curves (SCs) and the species distribution diagrams (SDDs) for the ZnCl2–NH4NO3-KOH-SC(NH2)2 system. The range of pH from 11.73 to 12.47 is proposed as a chemical condition obtained from the SCs and SDDs. The effects of these conditions on the structural, optical, morphological and stoichiometric properties of the films deposited at 70 °C were analyzed by x-ray diffraction (XRD), UV–Vis spectroscopy, scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS). XRD results show a main cubic crystalline structure (sphalerite) with (111) orientation, while the bandgap energy of the samples increases value from 3.44 eV to 3.72 eV with the increased pH. XPS technique evidenced a reduction of the Zn(OH)2 compound while the [Zn]/[S] ratio improved when the pH increased. SEM images allowed observing homogeneous surfaces and coalescence of grains on the surface of films.

Transformation of Heavy Metals during Pyrolysis of Predried Dyeing Sludge

Heavy metals in sludge may cause serious pollution and restrict the industrial application of sludge heat treatment. In this paper, predried dyeing sludge (PDS) char samples were prepared on a fixed bed in a pure nitrogen atmosphere. X-ray diffractometry, microwave digestion, and inductively coupled plasma-atomic emission spectrometry were used to measure the content, speciation occurrence, and the transformation of heavy metals during heat treatment of PDS samples. The results show that heavy metal elements such as Cr, Cu, Hg, Ni, and Pb in PDS both in raw PDS and derived char samples are mainly dominated by hydrochloric acid soluble speciation and insoluble speciation, while the ammonium acetate soluble speciation is very little and the water soluble speciation is negligible. Part of the hydrochloric acid soluble Cr is volatilized when pyrolyzed at 400–600 °C. Cr is mainly fixed in the PDS char as the insoluble speciation and hydrochloric acid soluble speciation above 600 °C. One part of the hydrochloric acid soluble Cu is volatilized and the other part transforms to the insoluble speciation at 400–500 °C. Cu is mainly fixed in the PDS char in the insoluble state above 600 °C. A small amount of Hg transforms from the hydrochloric acid soluble speciation to the gaseous speciation. Ni is observed to transform from the hydrochloric acid soluble speciation to the insoluble speciation below 700 °C, while it transforms from the insoluble speciation to the hydrochloric acid soluble speciation above 700 °C. The higher the temperature is, the more the ammonium acetate soluble Pb and the hydrochloric acid soluble Pb released to by volatilization as gaseous Pb. The fixing ratio of Cr, Cu, and Ni is proportional to the pyrolysis temperature, and the fixing ratio of Hg and Pb is inversely proportional to the pyrolysis temperature. PDS has a high fixing ratio of heavy metals at 700–800 °C, which indicates the best temperature window for heavy metal fixing. The present results may be helpful for the prevention and control of heavy metals in PDS.

Synthesis, characterization and electrochemical properties of isoflavone substituted zinc(II), cobalt(II), and metal-free phthalocyanines

In this study, novel tetrasubstituted metallo- and metal-free phthalocyanines containing 7-hydroxy-4′-methoxyisoflavonoxy moieties at peripheral and non-peripheral positions have been prepared by cyclotetramerization of corresponding phthalonitriles. The most obvious feature of these quaternized complexes is their extensive solubility and non-aggregated species (especially non-peripherally substituted) in organic solvents such as chloroform, tetrahydrofuran, dimethylformamide and dimethylsulfoxide, which makes them candidates for use in many applications in different fields. The new compounds have been characterized by elemental analysis, FT-IR, UV-vis, 1H and [Formula: see text]C NMR and MS (Maldi-TOF MS). Voltammetric and in situ spectroelectrochemical measurements have been performed with the aim of characterizing the electron transfer properties of the compounds on Pt in dimethylsulfoxide/tetrabutylammonium perchlorate, compared to those of previously reported corresponding compounds with tetra 6-hydroxyflavonoxy substituents. The effect of aggregation on the redox character of these complexes was also discussed.

Extended Deep Earth Water Model for predicting major element mantle metasomatism

Abstract Fluids in the deep crust and upper mantle appear to have played roles in the long-term evolution of the subcratonic lithospheric mantle and the stabilities of the continents, in the geochemical cycles of the elements from subduction zones to Earth’s surface environment, and in the formation of diamonds. Much evidence of the chemistry of deep fluids has accumulated from studies of fluid inclusions in diamonds and xenoliths. But the origins of the fluids and their behavior are still unclear. In part, this is due to the lack of a comprehensive theoretical model of aqueous, high-pressure fluids. Traditional models have used a C-O-H-type of model, which contains no major rock-forming elements or aqueous ions or metal-complexes. In the present study, we use experimentally measured solubility data for multicomponent K-free eclogite, K-free peridotite and K-bearing peridotite rocks at upper mantle conditions from the literature to construct aqueous speciation solubility models that enabled calibration of the thermodynamic properties of ions and metal-complex species involving the elements Na, K, Mg, Ca, Fe, Al, Si, and C in an extended Deep Earth Water (DEW) model. New equilibrium constants were retrieved for the aqueous bisilicate anion, a silica trimer, silicate complexes of Ca, Fe, and Al, a silicate complex of Mg and bicarbonate, and formate complexes of Fe and Ca. The aqueous speciation and solubility model also took account of decreases in the activity of water and aqueous activity coefficients of neutral dissolved gases and included consideration of H 2 CO 3 0 . Based on the temperature and pressure dependences of the equilibrium constants, and supporting data covering a wide range of conditions, we then developed aqueous equation of state characterizations of the ions and metal-complex species. Overall, the results form a basis for modeling fluid-rock interactions under upper mantle conditions consistent with experimental solubility measurements.

Studies on the nature of salicyl hydroxamate adsorption at the surface of neodymium oxide

Adsorption of salicyl hydroxamic acid (SHA) on neodymium oxide (Nd2O3) surfaces was studied at different SHA concentrations. The adsorbed surfaces were examined using X-Ray Diffraction (XRD) and Laser Raman Spectroscopy (LRS). XRD results show that the oxide remains intact until stoichiometric amounts equivalent to Nd(SHA)3 were exceeded. At lower concentrations, the behavior appeared to be an ion exchange of SHA with hydroxide as well as carbonates and chlorides. Results are attributed to a monolayer of chemisorbed SHA at low concentrations and multilayers of surface precipitated Nd(SHA)3 at higher concentrations. LRS corroborated these findings. Peaks from the C-H stretching band and C = N vibration bands were identified and areas under the peaks were quantified. Formation of the hydroxamate compound was ascertained from the C = N bands around 1597 cm−1. It was concluded that chelation occurs through chemical bonding of SHA with surface Nd confirming chemisorption and with trivalent Nd confirming surface precipitation. Thermodynamic calculations in the form of solubility speciation diagrams suggest that chemisorption predominates at moderate pH between 6 and 9 and surface precipitation predominates at higher pH between 9 and 12. Adsorption isotherms were determined for the monolayer and found to yield free energy values between physisorption and chemisorption but, due to the reaction being ion exchange, it was concluded to be chemisorption.

Temperature dependent control of the solubility of gallium nitride in supercritical ammonia using mixed mineralizer

Using a mass-loss method, we investigated the solubility change of gallium nitride (GaN) in supercritical ammonia with mixed mineralizers [ammonium chloride (NH4Cl) + ammonium bromide (NH4Br) and NH4Cl + ammonium iodide (NH4I)]. The solubilities were measured over the temperature range 450–550 °C, at 100 MPa. The solubility increased with NH4Cl mole fraction at 450 °C and 100 MPa. The temperature dependence of the solubility curve was then measured at an equal mole ratio of the two mineralizers. The slope of the solubility–temperature relationship in the mixed mineralizer was between those of the individual mineralizers. These results show that the temperature dependence of the solubility of GaN can be controlled by the mineralizer mixture ratio. The results of the van’t Hoff plot suggest that the solubility species were unchanged over the investigated temperature range. Our approach might pave the way to realizing large, high-quality GaN crystals for future gallium-nitride electronic devices, which are increasingly on demand in the information-based age.

Effect of Carbonate on the Migration Behavior of Lanthanides in Compacted Bentonite

ABSTRACTThe apparent diffusion coefficients of La, Nd, Eu, Dy, Er, and Lu in compacted bentonites were investigated at various bicarbonate concentrations. The apparent diffusion coefficients of these lanthanides tended to decrease with increasing dry density. At bicarbonate concentrations below 0.25 M, lanthanum had the largest diffusion coefficient (ca. 10-13 m2/s) at 1.0 Mg/m3, and the diffusion coefficient decreased with increasing atomic number. On the other hand, at bicarbonate concentrations above 0.25 M, lutetium had the largest diffusion coefficient, and the diffusion coefficient decreased with decreasing atomic number. In particular, lanthanum and neodymium had diffusion coefficients below 10-14 m2/s, even at 1.0 Mg/m3. The diffusion coefficient of europium was around 10-13 m2/s at 1.0 Mg/m3 and was influenced less by the bicarbonate concentration. The diffusion coefficient of lutetium increased from 2 × 10-14 to 10-12 m2/s as the bicarbonate concentration was increased to 1.0 M. The concentration of carbonate ion in the pore water of bentonite is estimated to be much lower than that in solutions in contact with bentonite from the viewpoints of solubility and chemical species of lanthanides.

Positively charged phthalocyanine-arginine conjugates as efficient photosensitizer for photodynamic therapy

Positively charged drugs usually have enhanced water solubility, cellular uptake efficiency and anticancer activity. However, the common quaternized and protonated cationic photosensitizers both have some drawbacks such as needing potentially dangerous agents for preparation and easily being deprotonated in alkaline circumstance. Arginine is unique among the amino acids as its guanidine group has exceptionally high basicity in aqueous solution, which may make it positively charged in a wide range of pH. In this paper, two arginine substituted zinc phthalocyanines (ArgEZnPc and ArgZnPc) were reported. They can be positively charged in the range of pH 5–9. Moreover, the photobiological, photochemical properties, subcellular localization, and in vitro anticancer activities of the them were also carried out. The results show that ArgZnPc may be not a good photosensitizer because of its poor photobiological activities though it is positively charged in a wide range of pHs. This may be attributed to the formation of inner salts between guanidine and carboxyl groups of ArgZnPc, which weakens its photobiological and in vitro anticancer activity. While in contrast, ArgEZnPc shows preferential localization in the lysosomes of HeLa cells, exhibits high water solubility, excellent 1O2 and intracellular reactive oxygen species generation efficiency as well as high in vitro anticancer activity, making it a promising photosensitizer for photodynamic therapy.

Synthesis of ZnS Thin Films by Chemical Bath: From Room Temperature to 90°C

A physicochemical analysis was performed on the solution used for synthetizing zinc sulfide (ZnS) films by chemical bath; such solution contained zinc chloride, potassium hydroxide, ammonium nitrate and thiourea as chemical reagents. Solubility curves and species distribution diagrams were used to obtain the best conditions for ZnS deposition in a wide range of bath temperatures between 25 and 90°C. Solubility curves evidenced the necessity to adjust the thiourea concentration for each bath temperature in order to obtain enough amounts of sulfur ions needed for ZnS formation. The thiourea concentrations were fixed at 0.2 M (90°C), 0.6 M (60°C), 1.25 M (40°C), and 2.25 M (25°C) to get higher quality films. Characterization results of films deposited at the conditions described above showed the films to have a bandgap energy value between 3.65 and 3.72 eV, stoichiometry of [Zn]/[S] ≈1, and homogeneous and agglomerate-free surfaces, which make them proper for solar cells applications.

Sorption, desorption, and speciation of Cd, Ni, and Fe by four calcareous soils as affected by pH.

The sorption, desorption, and speciation of cadmium (Cd), nickel (Ni), and iron (Fe) in four calcareous soils were investigated at the pH range of 2-9. The results indicated that sorption of Fe by four soils was higher than 80% at pH2, while in the case of Cd and Ni was less than 30%. The most common sequence of metal sorption at pH2-9 for four soils was in the order of Fe≫Ni>Cd. Cadmium and Ni sorption as a function of pH showed the predictable trend of increasing metal sorption with increase in equilibrium pH, while the Fe sorption trend was different and characterized by three phases. With regard to the order of Cd, Ni, and Fe sorption on soils, Cd and Ni showed high affinity for organic matter (OM), whereas Fe had high tendency for calcium carbonate (CaCO3). Results of metal desorption using 0.01M NaCl demonstrated that metal sorption on soils containing high amounts of CaCO3 was less reversible in comparison to soils containing high OM. In general, Cd and Ni desorption curves were characterized by three phases; (1) the greatest desorption at pH2, (2) the low desorption at pH3-7, and (3) the least desorption at pH>7. The MINTEQ speciation solubility program showed that the percentage of free metals declined markedly with increase of pH, while the percentage of carbonate and hydroxyl species increased. Furthermore, MINTEQ predicted that saturation index (SI) of metals increased with increasing pH.

Effects of Operating Temperature on the Electrical Performance of a Li-air Battery operated with Ionic Liquid Electrolyte

Li-air cell operated with ionic liquid electrolytes is a very promising energy storage technology for electric vehicle and plug-in hybrid electric vehicle due to several favorable characteristics of ionic liquids. However, Li-air cells that employ room temperature ionic liquid (RTIL) electrolytes exhibit poor performance due to limited oxygen solubility and low reactant species mobility. To circumvent these aforementioned drawbacks, we investigated the electrical performance of a Li-air cell with ionic liquid electrolytes operating at high temperature. A continuum based model is used to quantify the performance of the Li-air cell, with an ionic liquid (MPPY-TFSI) electrolyte, as a function of operating temperature. Simulations at the atomistic scale, such as molecular dynamics (MD) and density functional theory (DFT) calculations are used to obtain key properties for the continuum model. These properties include electron transfer reaction rate constant, species diffusivity and oxygen solubility. The MD simulations indicate that oxygen solubility in ionic liquid increases with temperature, which is very favorable for high temperature operation. The continuum based cell level simulation results show that the battery performance can be improved significantly by increasing operating temperature. For instance, specific capacity as high as 3000mAh/g can be achieved at 110°C operating temperature, which is almost 25 times higher than its counterpart at room temperature. Simulation results also reveal that by increasing the operating temperature, the specific capacity can be improved significantly for high load current density, which is one of the most critical drawbacks in RTIL based Li-air battery. We also studied the effect of cathode thickness on the performance of Li-air battery at different operating temperatures. The transport limitation of oxygen and lithium ions can be alleviated at higher operating temperatures, suggesting that even thicker cathode materials can be used to enhance the cell capacity at elevated temperature.

Impact of waterlogging on the uptake of arsenic by hyperaccumulator and tolerant plant

A significant proportion of arsenic (As)-contaminated sites are temporarily or permanently under reducing condition, which may affect phytoextraction efficiency using the As-hyperaccumulator Pteris vittata L. In this work, a pot experiment was conducted to investigate the solubility and redox species of As in soil. The uptake of As by two populations of P. vittata and As-tolerant grass Holcus lanatus under different water regimes was examined. Waterlogging decreased the redox potential from 350 to−50 mV, leading to an approximately 40% reduction of As(V) to As(III) and an increased dissolved As concentration by 150%–300%. The changes in the speciation and concentration of As influenced its uptake by plants. A population collected from a temporarily waterlogged riverside in Guangxi province (GX population) had ninefold higher shoot As concentration under the waterlogged condition than that under the non-waterlogged condition, indicating that it preferred taking up As in the form of As(III). By contrast, a population of P. vittata collected from a dry land in Yunnan province (YN population) and H. lanatus demonstrated a preference to As(V). The GX population was an appropriate species for the phytoextraction of waterlogged sites. These results implied the importance of habitat ecology on the extraction efficiency of hyperaccumulators.

Hydrogeochemical characterisation and modelling of groundwaters in a potential geological repository for spent nuclear fuel in crystalline rocks (Laxemar, Sweden)

Two sites in the eastern coast of Sweden have been investigated by the Swedish Nuclear Fuel and Waste Management Company (SKB), within the framework of the site characterisation programme, as possible candidates for hosting the proposed repository for the long-term storage of spent nuclear fuel: Forsmark and Laxemar. This study presents the main results concerning the hydrogeochemical characterisation of the groundwaters in the second site, Laxemar. The distribution of the main chemical variables in groundwaters are shown and interpreted in combination with the results from speciation–solubility and reaction-path simulations, together with the available mineralogical information. The results indicate that the main processes determining the overall geochemical evolution of the Laxemar groundwaters are advective/diffusive mixing and water–rock interactions driven by past and present climatic changes inducing the input of different recharge waters over time (glacial meltwater, old marine water and modern meteoric water) and affecting the preexisting very old saline groundwaters in the bedrock. The superimposed effects of these mixing events, deduced from the behaviour of the conservative elements (Cl and δ18O), have generated a rather steep salinity gradient in the groundwater system, with diluted waters in the upper part, brackish waters in the middle, and saline waters in the lower part of the bedrock.The resultant successive disequilibrium states imposed by mixing have conditioned the water–rock interaction processes that have affected the non-conservative elements to different degrees. The main chemical reactions found to be important in controlling some of the variability of these elements and some important parameters like pH and alkalinity, are: aluminosilicate and carbonate dissolution/precipitation, quartz and fluorite equilibrium, cation exchange, and gypsum dissolution. These reactions and their importance in the system are presented in this paper.Once the main hydrogeochemical features of the Laxemar groundwaters and the potentially controlling water–rock interactions in the system have been identified and justified with the help of thermodynamic simulations, a general geochemical conceptual model has been proposed. This model will be used as the basis for predicting the future evolution of the groundwater chemistry as an essential part of the safety assessment of the future repository.

The role of foreign cations in enhancing the oxygen solubility properties of alkali molten carbonate systems: Brief survey of existing data and new research results

Abstract This work presents a summary of experimental data on the oxygen solubility-speciation properties of alkali molten carbonates that have been obtained by the authors through the development of a highly sensitive analysis method. The purpose of this summary is to show in particular the effect of foreign cation additions on both oxygen solubility and dissolution mechanisms at 650 °C. Our findings may be used to clearly indicate that rare earth and magnesium cations are the most effective in enabling oxygen solubility and basicity/oxidizing melt properties. The second part of this work reports new experimental results concerning the effect of simultaneous additions of La and Mg cations to an eutectic Li/Na carbonate system. A dramatic increase in oxygen solubility and active peroxide oxygen species has been found, thus revealing a strong synergistic effect of rare earth and alkaline earth cations on the molten carbonate oxygen chemistry. The results of this investigation suggest therefore that foreign cation addition is a potentially attractive option to design alkali molten carbonate salts with a high oxidizing power.