TERNARY NaCl+LiCl+H2O MIXED ELECTROLYTE SYSTEM: DETERMINATION OF ACTIVITY COEFFICIENTS BASED ON POTENTIOMETRIC METHOD

The mean activity coefficients for NaCl in a ternary electrolyte system were determined by the potentiometric method, at 25°C, using a solvent polymeric (PVC) sodium-selective membrane electrode (Na⁺ ISE), containing N,N'-dibenzyl-N,N'-diphenyl-1,2-phenylenedioxydiacetamide as ionophore, and combined with an Ag/AgCl electrode. The potentiometric measurements were performed at the same ionic strengths in different series of mixed salt solutions, each characterized by a fixed salt molal ratio r (where r = m₁/m₂ = 1, 10, 50, 100). The nonideal behavior of the ternary NaCl(m₁) + LiCl(m₂) + H₂O electrolyte system was described based on the Pitzer ion-interaction model for mixed salts over the ionic strength ranging from 0.01 up to about 4 mol/kg. Two- and three-particle Pitzer interaction parameters for a mixed electrolyte system were determined based on potentiometric data, and the critical role of potentiometric selectivity coefficient (K₁₂) of ISE as limiting factor in the potentiometric measurements was analyzed.     

Kinetic analysis of Li|Li+ interphase in an ionic liquid electrolyte

Kinetic analysis of the Li|Li⁺ interphase in an electrolyte based on N-metyl-N-propylpyrrolidinium bis(trifluoromethanesulfon)imide ionic liquid (MPPyrrTFSI) and lithium bis(trifluoromethanesulfon)imide salt (LiTFSI) was performed. Li|electrolyte|Li and LiC₆|electrolyte|Li cells were galvanostatically charged/discharged in order to form solid electrolyte interphase (SEI) protecting layer. SEM images showed that the surface of both Li and LiC₆ anodes was covered with small particles. The fitting procedure of electrochemical impedance data taken at different temperatures gave three resistances (R _el, R _SEI, R _ct) and hence, three lnR = f(T ^?1) straight lines of different slopes. Specific conductivity and activation energy of the conduction process of the liquid electrolyte, were ca. σ = 2.5 mS cm^?1 (at T = 25.0 °C) and $ E_{\text{el}}^{\# } $  = 15 kJ mol^?1. Activation energy for the conduction process in the SEI layer was ca. 56 kJ mol^?1 in the case of the metallic lithium and 62 kJ mol^?1 for the graphite anode. Activation energy of the charge transfer process, $ E_{\text{ct}}^{\# } $ , for Li and LiC₆ anodes was 71 and 65 kJ mol^?1, respectively. Analysis of literature data for different electrolytes suggests that the $ E_{\text{ct}}^{\# } $ value for Li⁺ reduction may be approximated by 57 ± 5 kJ mol^?1. Activation energy for the diffusion processes in the graphite electrode, detected from the Warburg coefficient, was ca 74 kJ mol^?1.     

Thermodynamic modeling of CO2 solubility in aqueous solutions of NaCl and Na2SO4

A thermodynamic model based on the electrolyte NRTL activity coefficient equation and PC-SAFT equation-of-state is developed for CO₂ solubility in aqueous solutions of NaCl and Na₂SO₄ with temperature up to 473.15 K, pressure up to 150 MPa, and salt concentrations up to saturation. The Henry's constant parameters of CO₂ in H₂O and the characteristic volume parameters for CO₂ required for pressure correction of Henry's constant are identified from fitting the experimental gas solubility of CO₂ in pure water with temperature up to 473.15 K and pressure up to 150 MPa. The NRTL binary parameters for the CO₂-(Na⁺, Cl⁻) pair and the CO₂-(Na⁺, SO₄²⁻) pair are regressed against the experimental VLE data for the CO₂-NaCl-H₂O ternary system up to 373.15 K and 20 MPa and the CO₂-Na₂SO₄-H₂O ternary system up to 433.15 K and 13 MPa, respectively. Model calculations on solubility and heat of solution of CO₂ in pure water and aqueous solutions of NaCl and Na₂SO₄ are compared to the available experimental data of the CO₂-H₂O binary, CO₂-NaCl-H₂O ternary and CO₂-Na₂SO₄-H₂O ternary systems with excellent results.     

Ionic interactions and transport characteristics of a new polymer electrolyte system containing poly(propylene glycol) 4000 complexed with AgCF3SO3

The effect of concentration of AgCF₃SO₃ salt on the behavior of ionic transport within the polymer electrolyte system containing the polymer host poly(propylene glycol) of molecular weight 4000 (PPG4000) has been investigated in terms of spectroscopic and electrochemical properties. It is evident that the presence of well-defined interactions between the ether oxygens and silver cations arising due to the complexation of the silver salt with the polymer matrix has enabled the chosen polymer electrolyte system to possess the maximum room temperature (298 K) electrical conductivity of 9.4 × 10^?5 S cm^?1 in the case of the typical composition having the ether oxygen-to-metal ratio (O:M) of 4:1 and the lowest activation energy E _a of 0.46 eV for Ag⁺ ionic conduction.     

Revisiting electrolyte thermodynamic models: Insights from molecular simulations

Pitzer and electrolyte nonrandom two‐liquid (eNRTL) models are the two most widely used electrolyte thermodynamic models. For aqueous sodium chloride (NaCl) solution, both models correlate the experimental mean ionic activity coefficient (γ_±) data satisfactorily up to salt saturation concentration, that is, ionic strength around 6 m. However, beyond 6 m, the model extrapolations deviate significantly and diverge from each other. We examine this divergence by calculating the mean ionic activity coefficient over a wide range of concentration based on molecular simulations and Kirkwood–Buff theory. The asymptotic behavior of the activity coefficient predicted by the eNRTL model is consistent with the molecular simulation results and supersaturation experimental data. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3728–3734, 2018     

A study on polymer blend electrolyte based on PVA/PVP with proton salt

Proton-conducting polymer blend electrolytes based on PVA–PVP–NH₄NO₃ were prepared for different compositions by solution cast technique. The prepared films are investigated by different techniques. The XRD study reveals the amorphous nature of the polymer electrolyte. The FTIR and laser Raman studies confirm the complex formation between the polymer and salt. DSC measurements show decrease in T _g with increasing salt concentration. The ionic conductivity of the prepared polymer electrolyte was found by ac impedance spectroscopy analysis. The maximum ionic conductivity was found to be 1.41 × 10^?3 S cm^?1 at ambient temperature for the composition of 50PVA:50PVP:30 wt% NH₄NO₃ with low-activation energy 0.29 eV. The conductivity temperature plots are found to follow an Arrhenius nature. The dielectric behavior was analyzed using dielectric permittivity (ε*) and the relaxation frequency (τ) was calculated from the loss tangent spectra (tan δ). Using this maximum ionic conducting polymer blend electrolyte, the primary proton battery with configuration Zn + ZnSO₄·7H₂O/50PVA:50PVP:30 wt% NH₄NO₃/PbO₂ + V₂O₅ was fabricated and their discharge characteristics studied.     

Salt effect on the liquid–liquid equilibrium of the ternary (water + phenol + methyl isobutyl ketone) system: Experimental data and correlation

The effects of NaCl, KCl and Na_2SO_4 on the liquid–liquid equilibrium(LLE) data for the ternary system, water+ phenol + methyl isobutyl ketone, were determined at 0.101 MPa and 333.15 K and 343.15 K.The nonrandom two-liquid(NRTL) model was used to correlate the experimental data and to yield corresponding binary interaction parameters for these salt containing systems.The Hand and Othmer–Tobias equations were used to confirm the dependability of the determined LLE data in this work.Distribution coefficient and selectivity were used to evaluate the extraction performance of methyl isobutyl ketone with the existence of salt.The magnitude of salt effect on the water + phenol + methyl isobutyl ketone(MIBK) system is in the following order: Na_2SO_4NaClKCl.     

Extraction relationship of Li+ and H+ using tributyl phosphate in the presence of Fe(III)

ABSTRACT

During the extraction of lithium from high Mg-containing salt lake brines by tributyl phosphate (TBP) in the presence of Fe(III), H⁺ is used to stabilize Fe(III). However, the distribution ratio of H⁺ (D_H) is 4–6 times higher than that of Li⁺ (D_Li), which affects the extraction of Li⁺ significantly. In this study, the competition mechanism between H⁺ and Li⁺ was investigated by spectral analysis and thermodynamic equilibrium. The extracted species are determined as HFeCl₄ · 2TBP and LiFeCl₄ · 2TBP for H⁺ and Li⁺, respectively. The apparent equilibrium constants are K_H = 799.8 and K_Li = 120.6, respectively. Both equilibrium constants and the distribution ratios for H⁺ and Li⁺ extraction show that extraction of H⁺ is stronger than Li⁺.     

SOLUBILITIES,DENSITIES, AND REFRACTIVE INDICES FOR THE TERNARY SYSTEMS 1,2-PROPYLENE GLYCOL + MNO3 + H2O (M = Na,K, Rb,Cs) AT 25° AND 35°C

The solubilities, densities, and refractive index data for the 1,2-propylene glycol + MNO₃ + H₂O (M = Na, K, Rb, Cs) ternary systems at 25° and 35°C were measured with mass fractions of 1,2-propylene glycol ranging from 0 to 1.0. In all cases, the presence of 1,2-propylene glycol significantly reduces the solubility of the salts in aqueous solution. The experimental data of density, refractive index, and solubility of saturated solutions for these systems were correlated using polynomial equations. Furthermore, the refractive index and density of unsaturated ternary solutions were also determined and correlated with the salt concentrations and proportions of 1,2-propylene glycol in the systems.     

用电势法测定混合电解质溶液中各个组分的活度系数

本文用无液接电势电池：Ｎａ－ＩＳＥ（或Ｋ－ＩＳＥ）｜（ＮａＣｌ（ｍＡ），ＫＣｌ（ｍＢ），Ｈ２Ｏ｜Ｃｌ－ＩＳＥ同时测定了２９８．１５Ｋ，溶液离子强度Ｉ：０．１、０．５、１．０、１．５、２．０和２．５ｍｏｌ／ｋｇ时，钠电极与氯电极组成的电池和钾电极与氯电极组成的电池的可逆电势值，根据Ｎｅｒｎｓｔ方程分别求出ＮａＣｌ－ＫＣｌ－Ｈ２Ｏ体系中，ＮａＣｌ和ＫＣｌ的平均活度系数。用Ｐｉｔｚｅｒ方程拟合两套实验数据，求出两套基本一致的Ｐｉｔｚｅｒ混合参数θＮａ－Ｋ和。将混合参数代回Ｐｉｔｚｅｒ方程，分别求出另一组分的平均活度系数，计算值与实验值比较，标准偏差分别为：０．００８１（ＮａＣｌ）和０．００７３（ＫＣｌ）。     

Study of ionic charge dependent salt resistant swelling behavior and removal of colloidal particles using reduced <Emphasis Type="Italic">gum rosin</Emphasis>-poly(acrylamide)-based green flocculant

Present work reports the under pressure preparation of reduced gum rosin and acrylamide-based GrA-cl-poly(AAm) green flocculant. Characterization of the synthesized product was carried out by different techniques such as Fourier transform infrared spectroscopy, X-ray diffraction method and scanning electron microscopy. In addition, several variables such as time, physiological pH, solvent, pressure, monomer, cross-linking agent and initiator were examined to obtain maximum flocculation efficiency and explore the salt resistant swelling of the system. The maximum percentage swelling (P _s) at pH 7.0 and pressure 8.0 psi was found to be 578 %. Thermal behavior of the flocculant was investigated and the synthesized sample showed higher thermal stability than the gum rosin. The effect of ionic strength and charges of various cations (Na⁺, Ba⁺², Fe⁺³, Sn⁺⁴) on salt resistant swelling of GrA-cl-poly(AAm) flocculant, in different salt solutions such as sodium chloride, barium chloride, ferric chloride and stannic chloride (NaCl, BaCl₂, FeCl₃ and SnCl₄), was also studied. The synthesized sample was found to show ionic charge and salt concentration related behavior. Further, the removal of colloidal particles from wastewater through flocculation showed that GrA-cl-poly(AAm) exhibited significant flocculation efficiency (95.18 %) at a dose rate of 55 mg at 30 °C and pH 5.0. Flocculant capacity in saline medium was found to be maximum (99 %) at 1 % concentration. Further, increase in saline concentration resulted in decreased flocculant capacity. The kinetics of the aggregation of particles, deflocculation and reflocculation was analyzed through the Smoluchowski classical model based on first-order and second-order kinetics.     

Introducing copper ions into zeolite Y by the thallous ion exchange method: single crystal structure of |Cu21.6Tl39.2|[Si121Al71O384]–FAU

The thallous ion exchange (TIE) method was used for the first time in an attempt to introduce copper ions into zeolite Y (FAU, Si/Al = 1.69). |Cu _10.9 ⁺ Cu _10.7 ²⁺ Tl _39.2 ⁺ |[Si₁₂₁Al₇₁O₃₈₄]–FAU was prepared by reacting fully dehydrated and fully Tl⁺-exchanged zeolite Y (Tl₇₁–Y) with CuCl₂(g) and its decomposition products CuCl(g) and Cl₂(g) at 673 K under anhydrous conditions. Its structure was determined using single-crystal crystallography with synchrotron X-radiation and was refined in the space group ${Fd}\bar{3}$ m (a = 24.769(1) Å) with all 903 unique data; the final error index, R ₁ = 0.075, was calculated using only the 858 reflections with F _o > 4σ(F _o). About 45 % of the Tl⁺ ions were replaced by 21.6 copper ions per unit cell at the following sites (distances to nearest framework oxygen atoms are given): 10.7 Cu²⁺ at site I′ in the sodalite cavity opposite double 6-rings (Cu²⁺–O = 2.093(9) Å), 3.5 Cu⁺ at site II opposite single 6-rings in the supercage (Cu⁺–O = 2.24(3) Å), and 7.4 Cu⁺ at site III near 12-rings in the supercage (Cu⁺–O = 2.45(7) Å). All Cu⁺ ions are in supercages where they are easily accessible to guest molecules. The remaining ca. 39 Tl⁺ ions per unit cell occupy three distinct positions: 12 are at a second site I′ (Tl⁺–O = 2.571(9) Å), 23 are at a second site II (Tl⁺–O = 2.732(10) Å), and 4 are at site III′ (Tl⁺–O = 2.871(16) Å) near triple 4-rings in the supercages.     

Acceleration of the redox kinetics of VO2+/VO2 + and V3+/V2+ couples on carbon paper

The redox kinetics of VO²⁺/VO₂ ⁺ and V³⁺/V²⁺ couples on a carbon paper (CP, HCP030 N, Shanghai Hesen, Ltd., China) electrode were investigated in terms of their standard rate constant (k ₀) and reaction mechanism. The values determined for k ₀ for VO²⁺ ?? VO₂ ⁺ and V³⁺ ?? V²⁺ using the CP electrode are 1.0 × 10^?3 and 1.1 × 10^?3 cm s^?1, respectively. The value of k ₀ increases by one or two order(s) of magnitude compared with values obtained using electrodes composed of pyrolytic graphite and glassy carbon. The acceleration of the redox kinetics of vanadium ions is a result of the large surface area of the CP electrode. An inner-sphere mechanism for the reaction on the surface of the electrode is proposed. The kinetic features of vanadium redox reactions on the CP electrode reveal that CP is suitable for use as the electrodes in vanadium redox-flow batteries.     

Effect of nickel sulphate and magnesium sulphate on pH of sulphuric acid solutions at elevated temperatures

A flow-through potentiometric technique utilizing an yttria-stabilized zirconia (YSZ) pH sensor has been employed to elucidate the effects of NiSO₄ and MgSO₄ on pH of H₂SO₄ solutions at temperatures of 200 °C and 250 °C. Solution pH was found to increase with increasing NiSO₄ and MgSO₄ concentrations at both temperatures. This trend is attributed to the dissociation of NiSO₄ and MgSO₄ where the SO₄ ^2?(aq) released reacts with H⁺(aq) to form HSO₄ ^?(aq). The conversion of measured potentials into pH values was based on the mixed-solvent electrolyte (MSE) model, which is a speciation model of the new OLI Systems^® software. Both the Henderson equation and exact definition of the diffusion potential were employed in treating the obtained experimental data. Experimental pH values calculated using the diffusion potentials evaluated by either approach are similar, suggesting that the Henderson equation can be effectively used. In addition, LiCl was found to be a suitable alternative to NaCl as the reference electrode solution.     

MBr(M=Na,K)在离子液体[Bmim]Br水溶液中的溶解度

为探索溴化1-丁基-3-甲基咪唑([Bmim]Br)离子液体对无机溴化物MBr(M=Na,K)在水中溶解度的影响,采用等温溶解平衡法在常压下测定了298.15~328.15 K范围内MBr在[Bmim]Br(1)+H₂O(2)溶液中的溶解度,考察了离子液体含量对溶解度的影响。实验结果表明,[Bmim]Br的加入会显著降低MBr(M=Na,K)在水中的溶解度,离子液体[Bmim]Br对KBr的盐析作用比对NaBr的盐析作用大。不同温度下的溶解度数据可用Pitzer混合电解质溶液模型进行关联,得到了混合离子相互作用参数以及MBr在混合溶剂中的平均活度因子和溶剂的渗透系数。模型计算的溶解度与实验结果吻合良好,平均活度因子和溶剂的渗透系数均随离子液体含量的增加而增加。     

Treatment of Endocrine Disrupting Chemical From Aqueous Solution by Electrocoagulation

The removal of endocrine disrupting chemical (BPA; Bisphenol–A) from aqueous solution was experimentally investigated by electrocoagulation process. The effects of different combinations of aluminum (Al) and iron (Fe) electrode pair, supporting electrolyte type, supporting electrolyte concentration, initial pH and applied current density and initial BPA concentration on the Chemical Oxygen Demand (COD), and energy consumption performances were critically evaluated. The experiment results indicate that Al–Al electrode pair is the most efficient choice of the four electrode pairs. The COD removal efficiency was increased when NaCl was used as the supporting electrolyte instead of Na₂SO₄ and NaNO_3. The optimum supporting electrolyte type and its concentration, initial pH, applied current density and treatment time were found to be NaCl, 0.05 M, pH 7.0, 12 mA cm^?2 and 40 min, respectively. Energy consumption was found to decrease with increase of NaCl concentration while it increases with increasing applied current density. The initial and treated sample was characterized by UV–vis spectroscopy to confirm the treatment efficiency. The sludge formed during electrocoagulation was characterized by XRD and SEM/EDAX analysis.     

Preparation,Infra-red,MAS-NMR and Structural Characterization of a New Copper Based Inorganic–Organic Hybrid Compound: [C<Subscript>5</Subscript>H<Subscript>6</Subscript>N<Subscript>2</Subscript>Cl]<Subscript>2</Subscript>CuCl<Subscript>4</Subscript>

The ionic salt [2(C₅H₆N₂Cl)⁺], [CuCl₄]^2? complex of copper(II) has been synthesized and characterized. The X-ray diffraction analysis with a single crystal of this compound showed that the title compound (4-amino-2-chloropyridinium)₂CuCl₄ [(CAP)₂CuCl₄], crystallized at room temperature in the monoclinic system, space group C_2/c (N°.15) and the following : a = 16.0064 (2) Å; b = 7.7964 (10) Å; c = 14.7240 (2) Å; β = 102.497 (10)°; V = 1793.91 (4) ų and Z = 4. The structure was solved by using 1,589 independent reflections down to R value of 0.021. The unit cell is made up of tetrachlorocuprate(II) anions and 4-amino-2-chloropyridinium cations linked together by an extensive hydrogen bond network of types N–H···Cl (N: pyridinium) and N–H···Cl (N: amine), and cation-lone pair of nitrogen element interactions. Solid state NMR spectra showed one and five isotropic resonances, ⁶³Cu and ¹³C, respectively, confirming the solid state structure determined by X-ray diffraction. Impedance spectroscopy study, reported for single crystal, revealed that the conduction in the material was due to a hopping process. This work aims to reveal the thermal properties of a new copper(II) based organic–inorganic hybrid and the conductivity properties that these compounds exhibit.     

Sulfonate based ionic liquid incorporated polymer electrolytes for Magnesium secondary battery

The polymer electrolytes comprising of PVdF-HFP/PVAc/Mg(ClO₄)₂ as salt based polymer blend electrolytes derived from the addition of varying amounts of 1-ethyl – 3-methylimidazolium trifluoromethane sulfonate [EMITF], as dopant were synthesized in the form of films by solution-casting method. The XRD and FTIR patterns confirm the formation of an amorphous phase and also that complex formation between the polymers, salt and ionic liquid. The SEM images show that the polymer electrolyte exhibit a enormous pores, remarkably, the maximum ionic conductivity is obtained in the case of the typical polymer system I₃ is found to be 9.122 × 10^?4 Scm^?1at 303 K.     

Dielectric and Ion Transport Studies in [PVA: LiC2H3O2]: Li2Fe5O8 Polymer Nanocomposite Electrolyte System

The present work deals with the findings on optical and ion transport behavior in a ferrite-doped polymer nanocomposite electrolyte system, namely, [(100 ? x) PVA + xLiC₂H₃O₂]: yLiFe₅O₈. This polymer electrolyte system has been characterized by SEM, DSC, IR and C-V measurements. The addition of filler seems to disturb the crystalline nature of the host matrix while the doping of salt shows a similar structure, but with a separate entity in SEM images. DSC studies reflect the interaction of the salt/filler with polymer with a change in morphology of the composite system. These results are well-corroborated by IR data. The effect of salt or filler in the enhancement of the a.c. conductivity of nanocomposite polymer electrolyte (NCPE) as well as dielectric relaxation behavior has been investigated with the help of impedance spectroscopy data. The a.c. conductivity of nanocomposite polymer electrolytes is seen to be best described by the universal power law.