Investigation on cycling and calendar aging processes of 3.4 ah lithium-sulfur pouch cells

Much attention has been paid to rechargeable lithium-sulfur batteries (Li–SBs) due to their high theoretical specific capacity, high theoretical energy density, and affordable cost. However, their rapid c fading capacity has been one of the key defects in their commercialization. It is believed that sulfuric cathode degradation is driven mainly by passivation of the cathode surface by Li2S at discharge, polysulfide shuttle (reducing the amount of active sulfur at the cathode, passivation of anode surface), and volume changes in the sulfuric cathode. These degradation mechanisms are significant during cycling, and the polysulfide shuttle is strongly present during storage at a high state-of-charge (SOC). Thus, storage at 50% SOC is used to evaluate the effect of the remaining degradation processes on the cell’s performance. In this work, unlike most of the other previous observations that were performed at small-scale cells (coin cells), 3.4 Ah pouch Li–SBs were tested using cycling and calendar aging protocols, and their performance indicators were analyzed. As expected, the fade capacity of the cycling aging cells was greater than that of the calendar aging cells. Additionally, the measurements for the calendar aging cells indicate that, contrary to the expectation of stopping the solubility of long-chain polysulfides and not attending the shuttle effect, these phenomena occur continuously under open-circuit conditions

Evaluation of a wide rim phosphorylated calix[4]arene's properties as a sensory molecule in an Er(III)-PVC membrane sensor

This study concerns the evaluation of ionophoric properties of a functionalized calix 10 −7 -1 × 10 −3 M of erbium ions, with a limit of detection of 3.8 × 10 −8 M. Its potential response was independent of pH variation in the relatively wide range 4.5-6.5. The dynamic response time of the electrode to achieve a steady potential was found to be about 7 s. The selectivity of the sensor towards erbium ions with respect to several mono-, di-, tri-, and tetravalent metal ions was examined. The prepared sensor can be used for 3 months without considerable divergences in potential response. The performance of the sensor was examined as an indicator electrode for complexometric titration of erbium solutions by EDTA

Extraction-separation of Eu(III)/Th(IV) Ions with a Phosphorylated Ligand in an Ionic Liquid

ABSTRACT: Extraction-separation of Eu(III) and Th(IV) ions from nitrate media into the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate by a phosphorylated salen extractant, bis(chlorophosphoryle)decahydro-2,4-di(2-hydroxyphenyl)benzo[d][1,3,6]oxadiazepine (DPO), is investigated. It is found that Eu(III) ions are extracted via a solvation mechanism, and the extraction of Th(IV) ions proceeds through an ion exchange mechanism. The analysis of the experimental data reveals that the extraction of Eu(III) and Th(IV) ions is taken place by formation of Eu(DPO)(NO3)3 and Th(DPO)2(PF6)4 complexes. A significant selectivity towards thorium ions with respect to trivalent lanthanides was observed. Thorium(IV) can be efficiently extracted from nitric acid solutions into the studied ionic liquid in the presence of DPO

Selective Liquid-Liquid Extraction of Lead Ions Using Newly Synthesized Extractant 2-(Dibutylcarbamoyl)benzoic Acid

A new carboxylic acid extractant, named 2-(dibutylcarbamoyl)benzoic acid, is prepared and its potential for selective solvent extraction and recovery of lead ions from industrial samples was investigated. The slope analysis indicated that the lead ions are extracted by formation of 1:2 metal to ligand complexes. The effect of the parameters influencing the extraction efficiency including kind of the organic diluent, extractant concentration, type of the salt used for ionic strength adjustment, contact time and temperature was evaluated and discussed. Under optimized conditions (aqueous phase: 5 ml, initial lead concentration 1 × 10-4 M, pH 4, sodium chloride 0.1 M; organic phase: 5 ml dichloromethane, ligand concentration 0.05 M), a quantitative (75.2 ± 0.8%) and highly selective extraction of lead ions in the presence of zinc, nickel, cobalt and cadmium ions (each 1 × 10-4 M) was achieved, after 20 min. magnetically stirring of the phases, at      25 °C. The extracted lead ions were stripped from the organic phase by diluted nitric acid (0.1 M) solution. The proposed method was successfully applied for separation of lead from industrial samples. The study of the effect of temperature allowed evaluating the thermodynamic parameters of the extraction process of lead ions by the studied extractant into dichloromethane

Optimization of Continuous Flow Adsorption of Heavy Metal Ions on Continuous System Column by Peganum Harmala Seeds

Background & Aims of the Study: Heavy metals discharge to environment is a worldwide problem growing in scale. When they accumulate in the environment and in food chains, they can profoundly disrupt biological processes. Peganum Harmala Seeds (PHS) was used as a bio-sorbent, using a continuous system for removing Pb2+, Co2+, Ni2+ and Cu2+ ions from aqueous solutions. Materials and Methods: PHS was used as adsorbent in adsorption of heavy metals from aqueous solutions. A stock solution of Pb(II), Co(II), Cu (II) and Ni (II) was prepared and experiments were down in a column as a reactor. The concentration was determined by atomic adsorption spectroscopy. The effect of various parameters such as pH, contact time, heavy metal concentration, ionic strength, particle size and adsorbent dosage on the process was investigated. Langmuir, Frundlich and Temkin isotherms were studied to evaluate of adsorption isotherms. Results: The adsorption efficiency was found to be pH dependent and enhanced by increasing the solution pH. Maximum removal of ions were obtained at pH=4-8. The equilibrium time was attained after 30 min and desorption studies were performed, using diluted HNO3, H2SO4 and HCl solution (1M) on adsorbed metal ions from PHS. Results illustrated that adsorbed metal ions could be recovered under acidic conditions. Investigation of the process kinetic was best fitted with pseudo second-order model. Langmuir, Freundlich and Temkin models were tested for describing the equilibrium data. The Langmuir isotherm illustrated the best description of the cobalt and copper adsorption mechanism and Freundlich model describes lead and nickel ions adsorption on PHS. Conclusion: It was found that PHS would be a good adsorbent for removal of heavy metals

Effect of Polyethylene Glycols Dissolved in Aqueous Phase on the Extraction-Separation of La(III), Eu(III) and Er(III) Ions with Bis(2-ethylhexyl)phosphoric Acid

The present work concerns on the investigation of the role of polyethylene glycols (PEGs) as masking agent for amelioration of extraction-separation of La(III), Eu(III) and Er(III) ions by the acidic extractant bis(2-ethylhexyl)phosphoric acid (DEHPA). The studied solvent extraction system is based on the combination of chelating effect of DEHPA in the organic phase on the one hand, and the binding properties of the PEGs in the aqueous phase, on the other hand, to provide an improvement in separation of La(III), Eu(III) and Er(III) ions. The first part of this study deals with effect of diluent used as organic solvent on the separation efficiency of bis(2-ethylhexyl)phosphoric acid towards lanthanum, europium and erbium ions. Then, the influence of the presence of three polyethylene glycols, with molecular weights 200, 400 and 2000 (PEG200, PEG400 and PEG2000), in the aqueous phase on the separation of the studied metal ions was evaluated and discussed

Selective and Efficient Solvent Extraction of Copper(II) Ions from Chloride Solutions by Oxime Extractants

Oxime extractants 3-tert-butyl-2-hydroxy-5-methyl benzaldehyde oxime (HL1) and 3-tert-butyl-2-hydroxy-5-methoxy benzaldehyde oxime (HL2) were synthesized and characterized by conventional spectroscopic methods. Suitable lipophilic nature of the prepared extractants allowed examining the ability of these molecules for extraction-separation of copper from its mixture with normally associated metal ions by performing competitive extraction experiments of Cu(II), Co(II), Ni(II), Zn(II), Cd(II) and Pb(II) ions from chloride solutions. Both ligands transfer selectively the copper ions into dichloromethane by a cation exchange mechanism. Conventional log-log analysis and isotherm curves showed that Cu(II) ions are extracted as the complexes with 1:2 metal to ligand ratio by both extractants. Verification of the effect of the organic diluent used in the extraction of copper ions by HL1 and HL2 demonstrated that the extraction efficiency varies as: dichloromethane ~ dichloroethane > toluene > xylene > ethylacetate. Time dependency investigation of the extraction processes revealed that the kinetics of the extraction of copper by HL2 is more rapid than that of HL1. The application of the ligands for extraction-separation of copper ions from leach solutions of cobalt and nickel-cadmium filter-cakes of a zinc production plants was evaluated

On the Potential of a Poly(vinylidenefluoride-<i>co</i>-hexafluoropropylene) Polymer Inclusion Membrane Containing Aliquat^® 336 and Dibutyl Phthalate for V(V) Extraction from Sulfate Solutions

A polymer inclusion membrane (PIM) composed of 50 wt% base polymer poly(vinylidenefluoride-co-hexafluoropropylene), 40 wt% extractant Aliquat® 336, and 10 wt% dibutyl phthalate as plasticizer/modifier provided the efficient extraction of vanadium(V) (initial concentration 50 mg L−1) from 0.1 M sulfate solutions (pH 2.5). The average mass and thickness of the PIMs (diameter 3.5 cm) were 0.057 g and 46 μm, respectively. It was suggested that V(V) was extracted as VO2SO4− via an anion exchange mechanism. The maximum PIM capacity was estimated to be ~56 mg of V(V)/g for the PIM. Quantitative back-extraction was achieved with a 50 mL solution of 6 M H2SO4/1 v/v% of H2O2. It was assumed that the back-extraction process involved the oxidation of VO2+ to VO(O2)+ by H2O2. The newly developed PIM, with the optimized composition mentioned above, exhibited an excellent selectivity for V(V) in the presence of metallic species present in digests of spent alumina hydrodesulfurization catalysts. Co-extraction of Mo(VI) with V(V) was eliminated by its selective extraction at pH 1.1. Characterization of the optimized PIM was performed by contact angle measurements, atomic-force microscopy, energy dispersive X-ray spectroscopy, thermogravimetric analysis/derivatives thermogravimetric analysis and stress–strain measurements. Replacement of dibutyl phthalate with 2-nitrophenyloctyl ether improved the stability of the studied PIMs