Extending the solid solution range of sodium ferric pyrophosphate:Off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)as a novel cathode for sodium‐ion batteries

Iron‐based pyrophosphates are attractive cathodes for sodium‐ion batteries due to their large framework,cost‐effectiveness,and high energy density.However,the understanding of the crystal structure is scarce and only a limited candidates have been reported so far.In this work,we found for the first time that a continuous solid solution,Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2)(0≤α≤1,could be obtained by mutual substitution of cations at center‐symmetric Na3 and Na4 sites while keeping the crystal building blocks of anionic P_(2)O_(7) unchanged.In particular,a novel off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)is thus proposed,and its structure,energy storage mechanism,and electrochemical performance are extensively investigated to unveil the structure–function relationship.The as‐prepared off‐stoichiometric electrode delivers appealing performance with a reversible discharge capacity of 83 mAh g^(−1),a working voltage of 2.9 V(vs.Na^(+)/Na),the retention of 89.2%of the initial capacity after 500 cycles,and enhanced rate capability of 51 mAh g^(−1)at a current density of 1600 mA g^(−1).This research shows that sodium ferric pyrophosphate could form extended solid solution composition and promising phase is concealed in the range of Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2),offering more chances for exploration of new cathode materials for the construction of high‐performance SIBs.

New Exact Solutions of Multi-component mKdV Equation

In this paper, new Jacobi elliptic function solutions of multi-component mKdV equation are obtained directly in a unified way. When the modulus m → 1, those periodic solutions degenerate as the corresponding hyperbolic function solutions. Then, to the three-component mKdV equation, five types of effective solution are presented in detail.

Exact Periodic and Solitary-Wave Solutions of Multi-component Modified Korteweg-de Vries Equations

The present work extends the search of Jacobi elliptic function solutions for the multi-component modified Korteweg-de Vries equations. When the modulum m →1, those periodic solutions degenerate as the corresponding solitary wave and shock wave ones. Especially, exact solutions for the three-component system are presented in detail and graphically.

A Solute Pinning Approach to Solute Drag in Multi-Component Solid Solution Alloys

The Cahn, Lücke and Stüwe theory remains the backbone of more complex analysis dealing with solute drag, however, the mathematical treatment is rather involved. A new approach based on solute pinning the boundary has therefore recently been suggested, which has the main advantage of a simpler mathematical treatment. In the present paper this approach has been generalized to take into account the influence of different types of solute atoms in the high solute content/low driving force regime.

A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in aqueous solutions and its applications in binary and ternary aqueous solutions

A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in ternary and binary strong electrolyte aqueous solution was developed based on the ion and molecule coexistence theory and verified in four kinds of binary aqueous solutions and two kinds of ternary aqueous solutions. The calculated mass action concentrations of structural units or ion couples in four binary aqueous solutions and two ternary solutions at 298.15 K have good agreement with the reported activity data from literatures after shifting the standard state and concentration unit. Therefore, the calculated mass action concentrations of structural units or ion couples from the developed universal thermodynamic model for ternary and binary aqueous solutions can be applied to predict reaction ability of components in ternary and binary strong electrolyte aqueous solutions. It is also proved that the assumptions applied in the developed thermodynamic model are correct and reasonable, i.e., strong electrolyte aqueous solution is composed of cations and anions as simple ions, H2O as simple molecule and other hydrous salt compounds as complex molecules. The calculated mass action concentrations of structural units or ion couples in ternary and binary strong electrolyte aqueous solutions strictly follow the mass action law.

Role of Chloride Ion and Dissolved Oxygen in Electrochemical Corrosion of AA5083-H321 Aluminum-Magnesium Alloy in NaCl Solutions under Flow Conditions

Flow-induced corrosion consists electrochemical and mechanical components. The present paper has to assessed the role of chloride ion and dissolved oxygen in the electrochemical component of flow induced corrosion for AA5083-H321 aluminum-magnesium alloy which is extensively used in the construction of high-speed boats, submarines, hovercrafts, and desalination systems, in NaCI solutions. Electrochemical tests were carried out at flow velocities of 0, ：2, 5, 7 and 10 m/s, in aerated and deaerated NaCI solutions with different sodium chloride concentrations. The results showed that the high rate of oxygen reduction under hydrodynamic conditions causes an increase in the density of pits on the surface. The increase of chloride ions concentration under flow conditions accelerates the rate of anodic reactions, but have no influence on the cathodic reactions. Thus, in the current work, it was found that under flow conditions, due to the elimination of corrosion products inside the pits, corrosion resistance of the alloy is increased.

Separation and Concentration of Indium from Leaching Solution Containing Indium, Antimony and Iron Ions

Processing conditions of effectively separating indium from the leaching solution of a smelting antimony slag were studied. For the leaching solution containing indium and antimony and iron ions, indium was separated by extracting with HDEHP kerosine solution, washing antimony and iron ions with oxalic acid solution and stripping indium with a dilute solution of hydrochloric acid. InCl 3 solution with purity above 90% is obtained. Indium can be enriched through a circulation of stripping with a dilute HCl solution. The concentration of InCl 3 solution is about 25～30 g/L.

Effects of iron-containing phases on transformation of sulfur-bearing ions in sodium aluminate solution

Sulfides in the high-sulfur bauxite lead to serious steel equipment corrosion and alumina product degradation via theBayer process,owing to the reactions of sulfur and iron-containing phases in the sodium aluminate solution.The effects ofiron-containing phases on the transformation of sulfur-bearing ions(S2?,223S O?,23SO?and24SO?)in sodium aluminate solutionwere investigated.Fe,Fe2O3and Fe3O4barely react with23SO?and24SO?,but all of them,particularly Fe,can promote theconversion of223S O?to23SO?and S2?in sodium aluminate solution.Fe can convert to3Fe(OH)?in solution at elevatedtemperatures,and further react with S2?to form FeS2,but Fe2O3and Fe3O4have little influence on the reaction behavior of S2?insodium aluminate solution.Increasing temperature,duration,dosage of Fe,mole ratio of Na2Ok to Al2O3and caustic sodaconcentration are beneficial to the transformation of223S O?to23SO?and S2?.The results may contribute to the development oftechnologies for alleviating the equipment corrosion and reducing caustic consumption during the high-sulfur bauxite treatment bythe Bayer process.

A one-dimensional transport model for multi-component solute in saturated soil

A modified multi-component solute diffusion equation described with diffusion flux was derived in detail based on the classical MaxwellStefan diffusion theory. The friction between the solute species and the soil skeleton wall, which is proportional to the relative velocity between the solute species and the soil skeleton, is introduced. The chemical potential gradient is considered the driving force. A one-dimensional model for transport of multi-component solute in saturated soil was developed based on the modified diffusion equation and the modified competitive Langmuir adsorption equation. Numerical calculation of a case of two heavy metal ion species, which was chosen as an example, was carried out using the finite element software COMSOL Multiphysics. A comparative analysis was performed between the multi-component solute transport model developed in this study and the convection-diffusion transport model of single-component solute based on Fick's law. Simulation results show that the transport behavior of each species in a multi-component solute system is different from that in a single-component system, and the friction characteristics considered in the developed model contribute to obstructing the movement of each solute component. At the same time,the influence of modified competitive Langmuir adsorption on solute transport was investigated. These research results can provide strong theoretical support for the design of antifouling barriers in landfills and the maintenance of operation stability.

Soliton and rogue wave solutions of two-component nonlinear Schr?dinger equation coupled to the Boussinesq equation

The nonlinear Schrodinger （NLS） equation and Boussinesq equation are two very important integrable equations. They have widely physical applications. In this paper, we investigate a nonlinear system, which is the two-component NLS equation coupled to the Boussinesq equation. We obtain the bright-bright, bright-dark, and dark-dark soliton solutions to the nonlinear system. We discuss the collision between two solitons. We observe that the collision of bright-bright soliton is inelastic and two solitons oscillating periodically can happen in the two parallel-traveling bright-bright or bright-dark soliton solution. The general breather and rogue wave solutions are also given. Our results show again that there are more abundant dynamical properties for multi-component nonlinear systems.

Sorption of Manganese （II） and Chromium （III） Ions from Aqueous Solution Using Water Hyacinth Biomass （Eichhornia crassipes）

The use of water hyacinth biomass as adsorbent for Cr3＋ and Mn2＋ ions from aqueous solution by means of batch-adsorption technique was investigated to determine the potential ability of the biomaterial for metal ion removal. The equilibrium isotherm study showed that the maximum monolayer coverage on the biomass surface was 0.933 mg·g-1 and 0.874 mg·g-1 for Mn2＋ and Cr3＋ ions respectively. The highest percentage of Cr3＋ and Mn2＋ ions adsorbed by the biomass was 86.4% and 82.6% at the optimum pH of 4.0 and 6.0 respectively. The results also showed that the highest percentage removal 82.5% and 78.3% was obtained at 30 and 20 minutes respectively for Cr3＋ and Mn2＋ ions. The sorption process was examined by means of the Langmuir model. The adsorption equilibrium data were found to follow the Langmuir isotherm model with high coefficients of determination （R2 = 0.990 and 0.999） for Cr＋ and Mn2＋ ions respectively. The adsorption capacity of water hyacinth showed that water hyacinth will be useful in recovering chromium （III） and manganese （II） ions from solution and their subsequent removal from industrial effluents.

Ion exchange recovery of palladium (II) from nitrate weak acidic solutions

Sorption recovery of palladium (II) from nitrate weak acidic model solutions and solutions of spent catalysts on some ion exchangers with different physical and chemical structure has been investigated. The palladium concentration in contacting solutions was 5.0 ? 10-5 – 1.0 ? 10-3 mol/L at nitric acid and potassium nitrate con-centrations 0.01 and 1.0 mol/L, respectively. It was shown that anion exchangers AV-17-8 as well as Purolite S 985 and A 500 possess the best sorption and kinetic properties. These sorbents can be recommended for selective recovery of palladium from solutions of spent catalysts.

Spectra of sodium aluminate solutions

The UV spectra of sodium aluminate solutions were obtained in the sodium oxide concentration range from 59 to 409 g/L and the caustic ratio range from 1.5 to 4.0 to reveal the structure characteristics of them. It is found that a new peak appears at about 370 nm besides peaks at about 220 and 266 nm in all solutions. The new peak is strongly favored by high hydroxide concentration and high caustic ratio. And it only appears when the solutions are prepared by dissolving sodium hydroxide and aluminum hydroxide. In addition, the IR and Raman spectra of sodium aluminate solutions with high alkali concentration and high caustic ratio were measured, and the UV spectra of aqueous solutions of Al( H2O )36+and AlF 36?were measured as well. According to the crystal field theory in coordination chemistry as well as the above spectra characteristics, this new peak at about 370 nm is determined as the evidence of a new species of aluminate ion with a coordination number of 6.

Conductivity and applications of Li-biphenyl-1,2-dimethoxyethane solution for lithium ion batteries

The total conductivity of Li-biphenyl-1,2-dimethoxyethane solution（Li_xBp（DME）_（9.65）, Bp = biphenyl, DME = 1,2-dimethoxyethane, x = 0.25, 0.50, 1.00, 1.50, 2.00） is measured by impedance spectroscopy at a temperature range from 0℃ to 40℃. The Li_（1.50）Bp（DME）_（9.65） has the highest total conductivity 10.7 m S/cm. The conductivity obeys Arrhenius law with the activation energy（E_（a（x=0.50））= 0.014 eV, E_（a（x=1.00））= 0.046 eV）. The ionic conductivity and electronic conductivity of Li_xBp（DME）_（9.65） solutions are investigated at 20℃ using the isothermal transient ionic current（ITIC） technique with an ion-blocking stainless steal electrode. The ionic conductivity and electronic conductivity of Li_（1.00）Bp（DME）_（9.65） are measured as 4.5 mS/cm and 6.6 mS/cm, respectively. The Li_（1.00）Bp（DME）_（9.65） solution is tested as an anode material of half liquid lithium ion battery due to the coexistence of electronic conductivity and ionic conductivity. The lithium iron phosphate（LFP） and Li_（1.5）Al_（0.5）Ti_（1.5）（PO_4）_3（LATP） are chosen to be the counter electrode and electrolyte, respectively. The assembled cell is cycled in the voltage range of 2.2 V-3.75 V at a current density of 50 mA/g. The potential of Li_（1.00）Bp（DME）_（9.65） solution is about 0.3 V vs. Li~＋/Li, which indicates the solution has a strong reducibility. The Li_（1.00）Bp（DME）_（9.65） solution is also used to prelithiate the anode material with low first efficiency, such as hard carbon, soft carbon and silicon.

Dynamical behavior of traveling wave solutions of ion acoustic plasma equations

By using the theory of planar dynamical systems to the ion acoustic plasma equations, we obtain the existence of the solutions of the smooth and non-smooth solitary waves and the uncountably infinite smooth and non-smooth periodic waves. Under the given parametric conditions, we present the sufficient conditions to guarantee the existence of the above solutions.

Behavior of Cl^(-) Ions in Ag(SO_3)_2^(3-) Solution

l- ions behavior in Ag(SO_3)3-2 solution was studied. The mechanism of Ag particles formation in the solution was discussed, and factors affecting its formation were investigated.

Ion Mobility in the Fluorite Solid Solutions 50PbF₂–30BiF₃–20K(Na)F According to ¹⁹F, ²³Na NMR Data

Ion mobility in solid solutions of the fluorite structure 50Pb2–30BiF3–20KF (I) and 50Pb2–30BiF3–20NaF (II) was studied by NMR method. Analysis of 19F, 23Na NMR spectra made it possible to reveal the character of ion motions in the fluoride and sodium sublattices with temperature variation, to determine the types and temperature ranges in which they took place. It was found that the dominant form of ionic mobility in the samples I and II above 380 K was the diffusion of fluoride and sodium ions. According to preliminary results of electro-physical studies, the conductivity reached values of ~ 2×10–2 – 10–3 S/cm above 500 K. The solid solutions I and II can be recommended as a basis for use in the development of new functional materials.

Continuous changes in electrical conductivity of sodium aluminate solution in seeded precipitation

The mechanism of seeded precipitation of sodium aluminate solution was studied by measuring the seeded-precipitation rate and electrical conductivity online, as well as calculating the activity and fraction of ion pair. The results show that the electrical conductivity of sodium aluminate slurry linearly decreases with increasing aluminum hydroxide addition. Moreover, both the electrical conductivity of slurry and the difference in electrical conductivity between sodium aluminate solution and slurry remarkably decline in the first 60 min before gradually increasing in the preliminary 10 h and finally reaching almost the same level after 10 h. In low Na2 O concentration solution the activities of Na OH and Na Al（OH）4 in seeded precipitation are high, which can enlarge the difference in conductivity between slurry and solution. Additionally, more ion pairs exist in solution in preliminary seeded precipitation, and the adsorption of Na＋Al（OH）4- on seed surface is likely to break the equilibrium of ion pair formation and to decrease the difference in conductivity in preliminary seeded precipitation.

Modification to solution-diffusion model for performance prediction of nanofiltration of long-alkyl-chain ionic liquids aqueous solutions based on ion cluster

Mathematical modeling for nanofiltration of ionic liquids(ILs) solutions could assist to understand transfer mechanism and predict experimental values. In this work, modeling by solution-diffusion model for nanofiltration of long-alkyl-chain ILs aqueous solutions was proposed. Molecular simulations were performed to validate the existence of ion cluster in long-alkyl-chain ILs aqueous solution. Based on the results of simulations, parameters used in the solution-diffusion model were modified, such as concentration of ILs and diameter of ion cluster.The modeling process was developed for three long-alkyl-chain ILs aqueous solutions with different concentrations(1-alkyl-3-methylimidazolium chloride: [C6 mim]Cl, [C8 mim]Cl, [C10 mim]Cl). The calculated values obtained from modified solution-diffusion model could well match the experimental values.

Direct extraction of Mo(VI) from acidic leach solution of molybdenite ore by ion exchange resin:Batch and column adsorption studies

The adsorption behavior of ion exchange resin D301 in the extraction of hexavalent molybdenum from high acidic leach solution was investigated. SEM, EDS and Raman spectra analyses were applied to studying the adsorption capacity, reaction kinetics and possible adsorption mechanism in detail. Results showed that the adsorption capacity of D301 resin for molybdenum from high acidic leach solution was up to 463.63 mg/g. Results of the kinetic analysis indicated that the adsorption process was controlled by the particle diffusion with the activation energy 25.47 k J/mol（0.9-1.2 mm） and 20.38 k J/mol（0.6-0.9 mm）. Furthermore, the molybdenum loaded on the resin could be eluted by using 2 mol/L ammonia hydroxide solution. Besides, dynamic continuous column experiments verified direct extraction of molybdenum from acidic leach solutions by ion exchange resin D301 and the upstream flow improved dynamic continuous absorption.