Increase In Cation Concentration Research Articles

Influence of Cations on HCOOH and CO Formation during CO2 Reduction on a PdMLPt(111) Electrode.

Understanding the role of cations in the electrochemical CO2 reduction (CO2RR) process is of fundamental importance for practical application. In this work, we investigate how cations influence HCOOH and CO formation on PdMLPt(111) in pH 3 electrolytes. While only (a small amount of adsorbed) CO forms on PdMLPt(111) in the absence of metal cations, the onset potential of HCOOH and CO decreases with increasing cation concentrations. The cation effect is stronger on HCOOH formation than that on CO formation on PdMLPt(111). Density functional theory simulations indicate that cations facilitate both hydride formation and CO2 activation by polarizing the electronic density at the surface and stabilizing *CO2-. Although the upshift of the metal work function caused by high coverage of adsorbates limits hydride formation, the cation-induced electric field counterbalances this effect in the case of *H species, sustaining HCOOH production at mild negative potentials. Instead, at the high *CO coverages observed at very negative potentials, surface hydrides do not form, preventing the HCOOH route both in the absence and presence of cations. Our results open the way for a consistent evaluation of cationic electrolyte effects on both activity and selectivity in CO2RR on Pd-Pt catalysts.

A study on solubility of bismuth cations in nickel cobalt ferrite nanoparticles and their influence on dielectric and magnetic properties

In this work, a low temperature (∼600 °C) solution combustion technique is employed for the synthesis of Ni0.5Co0.5BixFe2-xO4 (NCBFO, where x = 0.0, 0.05, 0.1, 0.15, & 0.2) nanoparticles with crystallite size variation of 17–22 nm. The X-ray diffraction (XRD) technique is used to confirm the formation of cubic spinel phase of Bi3+ doped (for x ≤ 0.05 samples) nickel–cobalt ferrite (NCFO) nanoparticles. The increase in bismuth substitution (x > 0.05) results in the formation of the Bi2O3 along with the NCFO structure, which results in the reduction of binding energy and is confirmed by the XRD and X-ray photoelectron spectroscopy (XPS) techniques. From the Raman spectra, the change in the intensities of the peaks is observed due to the variation of Bi3+ in NCFO matrix. Due to increasing cation concentration and electronegativity, the FTIR absorption band shifts toward the lower wave numbers. Dielectric measurements were carried out to examine the charge transport behavior and electric conduction mechanism. The FESEM images shows the non-magnetic bismuth atoms are diffused into the NCFO nanoparticles. From the vibrating sample magnetometer (VSM) analysis, it is observed that saturation magnetization, remanent magnetization, coercivity and squareness ratio are found to be maximum for x = 0.15 NCBFO sample. The high coercivity (Hc = 916.8 Oe) for the x = 0.15 sample indicates the hard ferromagnetic behaviour of the samples.

An investigation of diuretic activity of aqueous extract of malus sulvestris (l) mil fruits in experimental animal models

Objective and background: Malus sylvestris Linn are a plant widely used as a traditional medicinal herb has a wide range of Pharmacotherapeutic activities. The current study was carried out to investigate the diuretic activity of Malus sylvestris Linn fruit aqueous extract (AEMS) in experimental animals. Methods: In the current study Wister rats were divided into 5 groups of n=6 each using Furosemide (100 mg/kg, p.o) as the standard drug and normal saline as the control. AEMS is given at the doses of 200 mg/kg, 400 mg/kg and 800 mg/kg p.o. in distilled water respectively. Lipchitz method was used for his study. Parameters such as volume of urine, concentration of sodium and concentration of potassium are noted. Results and discussion: The study revealed that extract of AEMS has considerably increased the urine volume with significant increase in cationic concentration at increased doses. The concentration of Na+/K+ indicates the dose dependent response with the comparable results at the doses of 200 mg/kg, 400 mg/kg and 800 mg/kg with reference with the standard administered. Oral administration of AEMS at the dose of 800 mg/kg shows high significance (P<0.001) with that of control and dose of AEMS of 400 mg/kg shows significance (P<0.05) shows and dose of AEMS of 200 mg/kg shows less significance (P<0.01) with decreased urine output with that of control. Conclusion: As a result of foregoing study aqueous extract of Malus sylvestris Linn fruit has considerable diuretic activity at higher doses.

Effect of permeants on fracture permeability in granite under hydrothermal conditions

Flow-through experiments were conducted with three permeants to determine the effect of pH, temperature, and cation concentrations on changes in permeability. Granite with a single fracture was used for each sample. Changes in the permeant concentrations due to pressure dissolution, free-face dissolution, and precipitation were identified by measuring the element concentrations before and after the experiments. In addition, the mineral transformation was analyzed by SEM-EDX. The results of the flow-through experiments showed a reduction in permeability in almost all the samples. This decrease in permeability may have been caused by the interaction between pressure dissolution and free-face dissolution, which occurred in the high pH water experiment, or between pressure dissolution and precipitation, which occurred in the saturated mineral water and simulated seawater experiments. When pressure dissolution and free-face dissolution occurred in the samples, the pH and temperature were seen to greatly affect the decrease in permeability, namely, the permeability decreased significantly with increasing pH and temperature. This remarkable decrease in permeability could have taken place because the dissolution rate constant of the mineral increased with the increasing pH and temperature. Moreover, when pressure dissolution and precipitation occurred in the samples, the cation concentrations and temperature were seen to greatly affect the changes in permeability, namely, the permeability decreased significantly with increasing cation concentrations and decreasing temperature.

Increasing ionic strength and valency of cations enhance sorption through hydrophobic interactions of PFAS with soil surfaces

The effect of soluble cations on sorption in soils of a range of anionic PFAS is not well studied. We investigated the role of three common cations (Na+, Ca2+, and Mg2+) at varying solution concentrations on the sorption coefficients (Kd) of 18 anionic PFAS in two contrasting soils. The effective charge of the soil suspension (Zeta potential) became less negative as the concentration of these cations increased in the soil solutions. Perfluorinated compounds showed greater sorption than polyfluorinated compounds, with sulfonates of comparable chain lengths showing higher sorption than the carboxylates. We observed that the Kd values of several PFAS in the two soils were positively correlated with the concentration of cations in solution, especially in the presence of polyvalent cations (Ca2+and Mg2+). The changes in sorption with cation concentration were more prominent for long-chain PFAS, with C > 10 PFAS being completely removed from solution at higher cation concentrations. The emerging PFAS (replacement compounds GenX and ADONA) showed negligible or little sorption (Kd < 0.6 L/kg). While several mechanisms contribute towards sorption of PFAS in the presence of cations, we conclude that the primary effect of cations is through screening of negative charges on head groups of PFAS and reorientation of molecules at the interface between organic matter surfaces and soil solution as well as charge neutralisation at soil solid surface. Screening of negative charges allows for greater hydrophobic interaction between hydrophobic tails of PFAS and soil surfaces resulting in greater sorption. Increasing cation concentrations in soil solutions could thus reduce mobility of PFAS through a soil profile.

Colloidal stability of nanosized activated carbon in aquatic systems: Effects of pH, electrolytes, and macromolecules

Nanosized activated carbon (NAC) is a novel adsorbent with great potential for water reclamation. However, its transport and reactivity in aqueous environments may be greatly affected by its stability against aggregation. This study investigated the colloidal stability of NAC in model aqueous systems with broad background solution chemistries including 7 electrolytes (NaCl, NaNO3, Na2SO4, KCl, CaCl2, MgCl2, and BaCl2), pH 4–9, and 6 macromolecules (humic acid (HA), fulvic acid (FA), cellulose (CEL), bovine serum albumin (BSA), alginate (ALG), and extracellular polymeric substance (EPS)), along with natural water samples collected from pristine to polluted rivers. The results showed that higher solution pH stabilized NAC by raising the critical coagulation concentration from 28 to 590 mM NaCl. Increased cation concentration destabilized NAC by charge screening, with the cationic influence following Ba2+ > Ca2+ > Mg2+ >> Na+ > K+. Its aggregation behavior could be predicted with the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory with a Hamaker constant (ACWC) of 4.3 × 10−20 J. The presence of macromolecules stabilized NAC in NaCl solution and most CaCl2 solution following EPS > BSA > CEL > HA > FA > ALG, due largely to enhanced electrical repulsion and steric hindrance originated from adsorbed macromolecules. However, ALG and HA strongly destabilized NAC via cation bridging at high Ca2+ concentrations. Approximately half of NAC particles remained stably suspended for ∼10 d in neutral freshwater samples. The results demonstrated the complex effects of water chemistry on fate and transport of NAC in aquatic environments.

Changes in soil salinity under treated wastewater irrigation: A meta-analysis

In view of water shortages, the development and utilization of unconventional water resources have been studied extensively. Treated domestic or industrial wastewater used for agricultural irrigation is an unconventional water resource utilization method. Due to the particularities of water sources, previous studies have mainly focused on changes in soil heavy metals, microorganisms, and organic substances and crop responses to toxic elements; thus, attention to soil salinity is of secondary importance. After selecting qualifying research, a meta-analysis was performed to statistically analyze the data of seven variables (potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), electrical conductivity (EC), pH, and yield) to 1) estimate the mean effects of treated wastewater (TWW) irrigation on the soil salinity, soil pH and crop yield; and 2) identify the wastewater treatment grade (primary treated wastewater (PTW), secondary treated wastewater (STW), and tertiary treated wastewater (TTW)) and soil texture (sandy texture, loamy texture and clayey texture) that benefit TWW irrigation. The results showed that TWW irrigation caused a significant accumulation of soil salinity, and the increase in cation content from high to low was K (90.1%), Na (59.9%), Mg (25.2%) and Ca (17.3%). EC also increased significantly by approximately 57.2%, while there was no significant change in pH, and even the crop yield presented an average reduction of nearly 6.5%. PTW contributed to the largest salt accumulation, followed by TTW and STW. STW showed a significant increase in EC but did not show a significant change for the four ions. In terms of yield, STW can increase yield, while TTW has the opposite effect. In general, the sandier the soil texture, the higher is the salt content detected, although the retention of salt in loamy textured soil may differ depending on the ions. The yield of crops grown increased in the clayey textured soil and decreased in the loamy textured soil. Our study elucidated the response of soil salinity accumulation under TWW irrigation and could provide a reference for unconventional water resource utilization.

Study of soil expansion characteristics in rainfall-induced red-bed shallow landslides: Microscopic and macroscopic perspectives.

The main cause of rainfall-induced red-bed shallow landslides is the tendency of red-bed weathered soil to expand when it meets water. However, studies on the expansion mechanism of expansive soil have not considered the effects of hydration and particle orientation. In this study, the hydration force of soil was determined according to the electric double-layer theory, the particle direction of soil was determined by analyzing images of soil obtained by scanning electron microscopy, and, finally, a microscopic model of the electrical double layer of red-bed weathered expansive soil was established in which the hydration force and soil-particle orientation were taken into account. The results showed that the expansion of red-bed weathered expansive soil is the result of hydration forces and repulsive forces in the electric double layer. The grain orientation of the soil strongly influenced the microscopic model. The unloading expansion rate of red-bed weathered expansive soil decreased with an increase in cation concentration and a decrease in pH value. It increased with an increase in the hydration cation radius. These experiments indicate the reliability of the microscopic model and provide a theoretical basis for the prevention and control of rainfall-induced red-bed shallow landslides.

Phase transition pathway of hydrothermal zeolite synthesis

Zeolites are aluminosilicate minerals with multiple channels and cages. They are widely used in industry; further, owing to its increasing demand, the hydrothermal synthesis of zeolites from natural minerals/rocks has attracted great attention. This study aims to discuss the crystal growth mechanisms of zeolites from pumice. Pumice is a widely available porous volcanic glass (mainly consisting of 65–75% SiO2 and 9–20% Al2O3) that can be used in the fabrication of zeolites. In this study, zeolite was formed from pumice via a hydrothermal method with varying alkaline concentrations, reaction times and temperatures, and addition of NaCl. Zeolite Na-P1 was synthesized under conditions of 0.1 or 0.5 M at 150 °C. The feldspar phase (albite) initially occurred, followed by the zeolite phase (zeolite Na-P1). Phillipsite was an unstable intermediate product during this synthesis process. Based on these results, we suggest that the phase transformation sequence follows the order of albite, phillipsite, and zeolite Na-P1. Moreover, it can be speculated that an increase in cation concentration can induce a rapid occurrence of the zeolite phase (zeolite Na-P1). Raman spectrometry analyses provided insights into the formation mechanism of zeolite structures, indicating differences related to the number of sodium ions. Both zeolite Na-P1 and phillipsite are composed of four- and eight-membered rings, and the former is mainly grown with four-membered rings as the main structure. This study provides a low-cost and simple synthetic method for producing zeolite Na-P1 and phillipsite, which can be used as indicator minerals for marine/lake facies and in environmental treatment.

Density functional study on structural and optoelectronic properties of cubic $$\hbox {Mg}_{x}\hbox {Zn}_{1-x}\hbox {S}_{y}\hbox {Se}_{1-y}$$ semiconductor quaternary alloys

In the case of technologically important quaternary alloys, structural and optoelectronic properties have been calculated with density functional theory (DFT)-based full-potential linearised augmented plane-wave (FP-LAPW) approach. The Perdew–Burke–Ernzerhof generalised gradient approximation (PBE-GGA) for structural properties and both the modified-Becke–Johnson (mBJ) and Engel and Vosko GGA (EV-GGA) for optoelectronic properties are employed to calculate the respective exchange-correlation potentials. Each specimen within the quaternary system is a direct band-gap – semiconductor. The lattice constant decreases, while bulk modulus and band gap increase nonlinearly with increasing anionic (S) concentration at each cationic (Mg) concentration . On the other hand, nonlinear increment in lattice constant and band gap, but decrement in bulk modulus is found with increase in cationic concentration at each anionic concentration . Calculated contour maps for lattice constants and energy band gaps would be useful in fabricating new quaternary alloys with preferred optoelectronic features. Optical properties of the specimens within the quaternary system show several interesting features. , 4p and 4p optical excitations contribute intense peaks in each spectrum. The composition dependence of each calculated zero-frequency limit shows opposite trend, while each calculated critical point shows similar trend of composition dependence of band gap. Moreover, calculations suggest the possibility of growth of several cubic quaternary specimens on GaAs and InP substrates.

Evaluation of Different ISORROPIA-Ⅱ Modes and the Influencing Factors of Aerosol pH Based on Tianjin Online Data

Aerosol acidity is closely related to particle properties and the explosive growth of secondary particles. Aerosol pH is difficult to measure directly but can be estimated indirectly by thermodynamic equilibrium modeling. ISORROPIA-Ⅱ is one of the most commonly used thermodynamic models and includes different modes (forward and reverse) and aerosol states (stable and metastable). Studies have shown that the calculated pH results vary with the selected mode and phase state. In addition to the selection of modes and phases, there are also other factors that influence the modeling results. In order to explore the appropriate mode and phase selection of ISORROPIA-Ⅱ as well as the factors influencing the model results under the air pollution characteristics of typical Chinese cities, the simulation results of different modes and aerosol states were analyzed by using online hourly data for Tianjin. The results showed that the pH calculations using the forward mode and metastable state were satisfactory at a higher RH. With increased temperature, the pH, aerosol water content, and concentration proportion in the aerosol phase of semi-volatile components all decreased. RH affected aerosol pH by influencing the aerosol water content and concentration of semi-volatile components. An increased cation concentration led to an increased pH and NH3 concentration but a decreased HNO3 concentration, whereas an increased anion concentration had the opposite effect. Ca2+, SO42-, NO3-, and NH4+ had a great influence on pH. Compared with SO42-, NO3- had less effect on pH. Sensitive areas exist in the influence of NH4+ on pH, and a high NH4+ concentration did not cause a continuous pH increase. This study can improve the understanding of aerosol pH simulation using ISORROPIA-Ⅱ, and provides reference for research on the pH-related secondary generation mechanism, semi-volatile component gas-particle distribution, and pollution control measures.

Near field non-invasive electrophysiology of retrotrapezoid nucleus using amperometric cation sensor

Central chemoreception is the process whereby the brainstem senses blood gas levels and adjusts homeostatic functions such as breathing and cardiovascular tone accordingly. Rodent evidence suggests that the retrotrapezoid nucleus (RTN) is a master regulator of central chemoreception, in particular, through direct sensation of acidosis induced by CO2 levels. The oscillatory dynamics caused by pH changes as sensed by the RTN surface and its relationship to the fluctuations in cation flux is not clearly understood due to the current limitations of electrophysiology tools and this article presents our investigations to address this need. A cation selective sensor fabricated from polypyrrole doped with dodecyl benzenesulfonate (PPy (DBS)) is placed over RTN in an ex-vivo en bloc brain and changes in cation concentration in the diffusion limited region above the RTN is measured due to changes in externally imposed basal pH. The novelty of this technique lies in its feasibility to detect cation fluxes from the cells in the RTN region without having to access either sides of the cell membrane. Owing to the placement of the sensor in close proximity to the tissue, we refer to this technique as near-field electrophysiology. It is observed that lowering the pH in the physiological range (7.4–7.2) results in a significant increase in cation concentration in the vicinity of RTN with a median value of ~5 μM. The utilization of such quantifiable measurement techniques to detect sub-threshold brain activity may help provide a platform for future neural network architectures. Findings from this paper present a quantifiable, sensitive, and robust electrophysiology technique with minimal damage to the underlying tissue.

First principle investigations of structural and optoelectronic features of cubic CdxZn1−xSyTe1-y quaternary semiconductor alloys

In case of technologically important CdxZn1−xSyTe1−y quaternary alloys, structural and optoelectronic properties have been calculated for the first time with DFT based FP-LAPW approach. The PBE-GGA functional for structural properties and mainly the mBJ functional for optoelectronic properties are employed to calculate respective exchange-correlation potentials. Each specimen within CdxZn1−xSyTe1−y quaternary system is a direct band gap (Γ-Γ) semiconductor. The lattice constant reduces, while bulk modulus and band gap enhances nonlinearly with increasing anionic (S) concentration y at each cationic (Cd) concentration x. On the other hand, nonlinear increase in lattice constant, but decrease in bulk modulus and band gap is observed with increase in cationic concentration x at each anionic concentration y. Calculated contour maps for lattice constants and energy band gaps would be useful in fabricating new ternary or quaternary alloys with preferred optoelectronic features. Optical properties of the said specimens within CdxZn1−xSyTe1−y quaternary system show several interesting features. The composition dependence of each calculated zero-frequency limit shows opposite trend, while each calculated critical point shows similar trend of composition dependence of band gap. Moreover, calculations suggest the possibilities of growth of several zinc-blende (B3) CdxZn1−xSyTe1−y quaternary specimens on ZnTe, InP and GaAs substrates.

First principles investigations of structural and optoelectronic properties of cubic MgxZn1−xSeyTe1−y quaternary semiconductor alloys using FP-LAPW approach

Structural and optoelectronic properties of technologically important MgxZn1−xSeyTe1−y quaternary alloys are calculated employing DFT-based FP-LAPW approach. Computations of exchange–correlation potentials are performed with PBE-GGA for structural properties and both the mBJ and EV-GGA for optoelectronic properties. Each specimen within MgxZn1−xSeyTe1−y system is a direct band gap (Γ–Γ) semiconductor. At each cationic (Mg) concentration x, lattice constant decreases, while bulk modulus and band gap increase nonlinearly with increase in anionic (Se) concentration y. Again, nonlinear increase in lattice constant and band gap, while decrease in bulk modulus is observed with increase in cationic concentration x at each anionic concentrations y. Calculated band gap bowing for few ternary alloy systems are in good agreement with corresponding experimental data. The calculated contour maps for lattice constants and energy band gaps would be very useful for designing new quaternary alloys with desired optoelectronic properties. Optical properties of the said specimens within MgxZn1−xSeyTe1−y quaternary system show several interesting features. Composition dependence of each calculated zero-frequency limit shows opposite trend, while each calculated critical point shows similar trend of composition dependence of band gap. Finally, suitability of ZnTe and InAs as substrates for the growth of several zinc-blende MgxZn1−xSeyTe1−yquaternary alloys has been investigated.

Effects of Cation on the Morphology of Boehmite Precipitated from Alkaline Solutions by Adding Gibbsite as Seed

Regulation of boehmite morphology is important for improving its performance in applications. In this paper, the dependence of boehmite morphology on cation ions was studied by XRD, SEM, TEM, FTIR, and zeta-potential, together with calculation of ion degree of association. Boehmite was respectively precipitated from sodium, potassium, lithium, or barium alkaline solution by adding gibbsite as seed at 180 °C for 2 h. Cation concentration and species determined the boehmite morphology. Increase in cation concentration or precipitation in K+, Na+, Li+, and Ba2+ alkaline solution correspondingly precipitated rhombic, hexagonal, and elliptical morphology for boehmite. Al(OH)4– was predominantly found in filtrate solution by Raman spectra, whereas red shift of FTIR was observed in alkaline solution containing Ba2+, Li+, Na+, and K+ cations. The degree of association of Mn+[Al(OH)4–]nn− increased in the following order: Ba2+[Al(OH)4–]2 > Li+Al(OH)4– > K+Al(OH)4– > Na+Al(OH)4– in the same concentration of cation solution. This finding agreed with the variations in FTIR change and zeta potential. Meanwhile, increasing cation and Al(OH)4– concentration or precipitation in lithium or barium alkaline solution caused the (202) facet of boehmite to gradually disappear and the (200) facet to be exposed. Therefore, the selective adsorption of ion pairs on the (202) and (200) facet of boehmite mainly accounted for the boehmite morphology.

Inhibition of Cathodic Kinetics by Zn2+ and Mg2+ on AA7050-T7451

The inhibitory effects of Mg2+ and Zn2+ on the cathodic kinetics of AA7050-T7451 were investigated by both electrochemical techniques and surface characterization tools. This study focused on the effects of Zn2+/Mg2+ concentration and immersion time. It has been found that in the cathodic potential regime where the oxygen reduction reaction (ORR) was dominant, Mg(OH)2 and NaZn4(SO4)(OH)6Cl⋅6H2O were precipitated on Cu-bearing intermetallic compounds (IMCs) embedded in AA7050-T7451 in Mg2+-and Zn2+-containing solutions, respectively. Both formed a barrier to oxygen diffusion, thus lowering the cathodic limiting current density. The decrease in cathodic limiting current density pertinent to ORR was proportional to Mg2+/Zn2+ concentration. At short times, both ions decreased the open circuit corrosion rate, with the inhibition increasing with increased cation concentration. Better inhibition was provided by Zn2+ than by Mg2+ at the same ion concentration. The corrosion inhibitive effect of Mg2+ was inferior to Zn2+ during the first 120hrs, but was inferred to be superior to Zn2+ for an immersion exposure period longer than 120hrs.

Gellan gum fluid gels: influence of the nature and concentration of gel-promoting ions on rheological properties

Low-acyl gellan gum fluid gels were obtained using two different gel-promoting cations under the same processing conditions, and their rheological properties were investigated. For that reason, stress and frequency sweep measurements and flow curve tests were carried out. Small amplitude oscillatory shear assays demonstrated that these materials exhibit weak gel behavior despite the shape of their mechanical spectra being similar to those obtained from strong gels. However, the existence of a weak gel structure was confirmed by the fact that the difference between the elastic and viscous components was of only one order of magnitude. In addition, a reduction in the storage and lost modules and the viscosity as a function of the applied shear was observed with increasing cation concentration. Finally, in order to produce fluid gels, a higher concentration of the monovalent cation was required than when divalent cations were employed in the low-acyl gellan gum fluid gel formulation.

Complexation of the Mycotoxin Cyclopiazonic Acid with Lanthanides Yields Luminescent Products.

Cycopiazonic acid (CPA) is a neurotoxin that acts through inhibition of the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA). CPA blocks the calcium access channel of the enzyme. The inhibition may involve the binding of CPA with a divalent cation such as Mg2+. The potential for CPA to act as a chelator also has implications for methods to detect this toxin. Certain of the lanthanide metals undergo a dramatic increase in luminescence upon coordination with small molecules that can transfer excitation energy to the metal. This report is the first to describe the coordination of CPA with lanthanide metals, resulting in a substantial enhancement of their luminescence. The luminescence expressed was dependent upon the type of lanthanide, its concentration, and the environment (solvent, water content, pH). Based upon the phenomenon, a competitive assay was also developed wherein terbium (Tb3+) and a series of metal cations competed for binding with CPA. With increasing cation concentration, the luminescence of the CPA/Tb3+ complex was inhibited. The chlorides of ten metals were tested. Inhibition was best with Cu2+, followed by Co2+, Al3+, Fe3+, Mn2+, Au3+, Mg2+, and Ca2+. Two cations in oxidation state one (Na+, K+) did not inhibit the interaction significantly. The interaction of CPA with lanthanides provides a novel recognition assay for this toxin. It also provides a novel way to probe the binding of CPA to metals, giving insights into CPA’s mechanism of action.

Effect of coexisting ions on recovering lithium from high Mg2+/Li+ ratio brines by selective-electrodialysis

Abstract Selective-electrodialysis (S-ED) is a booming technology for recovering lithium from salt lake brine and (concentrated) seawater, especially from high Mg2+/Li+ ratio brines. The coexisting ions in the solutions containing lithium can make some impact on the ion fractionation of lithium and magnesium in high Mg2+/Li+ brines. The effect of the concentration of coexisting cations (Na+, K+) and anions (SO42−, HCO3−) on the separation coefficient of magnesium and lithium (FMg-Li), recovery ratio of Li+ (RLi), current efficiency (η) and specific energy consumption (ESEC) was evaluated. The results show that an applied voltage of 6 V is more preferable for lithium ions recovery from high Mg2+/Li+ brines by S-ED. The separation of Mg2+/Li+ tends to unsatisfactory with increasing cation concentration (Na+, K+), and FMg-Li drops from 8.73 to 1.83 with the increase of Na+/Li+ from 1 to 5 and from 8.33 to 2.13 with the rise of K+/Li+ from 1 to 5. The strength of influence on the separation of Mg2+/Li+ is K+ > Na+, correlating with the order of their hydrated ion radiuses. However, FMg-Li rises from 7.99 to 14.66 with the increase of SO42−, reversing with the influence of cations concentration. As for HCO3−, the variation tendency of FMg-Li is opposite to RLi, probably ascribing to the appearance of MgHCO3+. These observations showed that S-ED has a wide adaptability for the ion fractionation of magnesium and lithium from brines.

Photochemical Formation and Transformation of Birnessite: Effects of Cations on Micromorphology and Crystal Structure.

As important components with excellent oxidation and adsorption activity in soils and sediments, manganese oxides affect the transportation and fate of nutrients and pollutants in natural environments. In this work, birnessite was formed by photocatalytic oxidation of Mn2+aq in the presence of nitrate under solar irradiation. The effects of concentrations and species of interlayer cations (Na+, Mg2+, and K+) on birnessite crystal structure and micromorphology were investigated. The roles of adsorbed Mn2+ and pH in the transformation of the photosynthetic birnessite were further studied. The results indicated that Mn2+aq was oxidized to birnessite by superoxide radicals (O2•-) generated from the photolysis of NO3- under UV irradiation. The particle size and thickness of birnessite decreased with increasing cation concentration. The birnessite showed a plate-like morphology in the presence of K+, while exhibited a rumpled sheet-like morphology when Na+ or Mg2+ was used. The different micromorphologies of birnessites could be ascribed to the position of cations in the interlayer. The adsorbed Mn2+ and high pH facilitated the reduction of birnessite to low-valence manganese oxides including hausmannite, feitknechtite, and manganite. This study suggests that interlayer cations and Mn2+ play essential roles in the photochemical formation and transformation of birnessite in aqueous environments.