Kinds Of Anions Research Articles

The role of anions for phosphoric acid uptake behaviors and electrochemical performance of ion-pair type high-temperature polymer electrolyte membranes

Quaternized ion-pair membranes have high phosphoric acid (PA) uptake and retention due to strong interaction energy between quaternary ammonium with PA. However, there is currently a lack of clear understanding of the role of anions on the PA uptake behaviors and mechanism of ion-pair type membranes. In this work, the PA uptake behaviors of quaternized poly (terphenyl piperidinium) (QAPTP-X, X represents anions) with four kinds of anions (Cl−, OH−, HCO3− and H2PO4−) were investigated. Due to the neutralization reaction between PA and OH−/HCO3−, QAPTP-OH− and QAPTP-HCO3− membranes show a faster PA adsorption rate (PA uptake for 2 min: 116 wt% of QAPTP-OH−≈109 wt% of QAPTP-HCO3− >95 wt% of QAPTP-H2PO4− ≫64 wt% of QAPTP-Cl−). Besides, the Pt catalyst is poisoned by strong adsorption anions Cl− migrated from the QAPTP-Cl− membrane, which leads to sluggish electrode reaction kinetics and lower peak density. Therefore, a new perspective is provided for studying the mechanism of PA uptake and electrochemical performance for ion-pair type membranes.

Validation Study on Developed Methods for Anions and Bromic Acid in Various Mineral Waters by Ion Chromatography

Five kinds of anions namely fluoride, chlorate, chlorite, nitrate and nitrite ions, and bromic acid were determined in various mineral waters (MWs), and the methods were validated. MWs are varying in the degree of hardness and contents of carbonate. When the five anions were measured based on the official method of tap water, the peak shape of fluoride ion in MWs with high degree of hardness was different from the standard solution, making it difficult to determine. The same phenomenon was also observed when bromic acid was measured. In order to achieve accurate determination, five-fold dilution with ultrapure water was carried out on the samples. With the additional step, the abnormal peak of both analytes was improved, and no difference in the retention times between standard and sample solutions was observed. The validation tests were performed using the developed methods with the additional diluting step, and the results of all target substances met the criteria of the guideline on analytical method validation for MW in Japan. Our results suggested that the methods we developed could be useful for the accurate determination of the anions and bromic acid in various MWs on the market.

A new organic zinc thermal stabilizer containing two kinds of anions with excellent thermal stability on polyvinyl chloride by multistep substitution

AbstractA new kind of highly efficient organic zinc thermal stabilizer for polyvinyl chloride (PVC), zinc arginine stearate [Zn(Arg)(St)], is designed by introducing the arginine and stearate to the same zinc atoms to regulate the binding energy between anions and cation. Gaussian soft is used to calculate the binding energy. The results of Fourier transform infrared spectra, elemental analysis, thermogravimetric analysis, and differential scanning calorimetry show that Zn(Arg)(St) has been successfully synthesized. Zn(Arg)(St) stabilized PVC displays excellent Congo red, static and dynamic thermal stability time, especially the excellent initial whiteness and whiteness retention time. The thermal stability mechanism of Zn(Arg)(St) attributes to the different binding energy between the two anions and zinc cation, which results in Zn(Arg)(St) continuously replacing the unstable chlorine atoms step by step by Arg and St anions. Moreover, the amino group in Arg could complex ZnCl2 to inhibit the “zinc burning” effect, and the guanidine group could absorb HCl to inhibit the “autocatalytic effect” of HCl. In addition, Zn(Arg)(St) has a remarkable lubrication effect, which also enhances the thermal stability of PVC. Thus, Zn(Arg)(St) is an environmentally friendly thermal stabilizer for PVC with an excellent thermal stability effect. Importantly, this work also proposes a new method to design highly efficient thermal stabilizers for PVC.

New perspectives on the multianion approach to adapt electrode materials for lithium and post-lithium batteries.

Developing new and sustainable batteries is essential for modern society. Both cationic doping (e.g. transition metals) and anionic doping (F-, O2-, S2-, PO43-, etc.) can be employed to improve the electrochemical behaviour of electrode materials. Herein, the anion-doping, or multianion approach, is comprehensively reviewed and investigated. It is observed that the optimized compositions of some electrode materials can involve metastable or transient states. Going beyond the inductive effect, we propose that the simultaneous use of several kinds of anions in the framework of the same host material could create a sort of energized state in the electrode material, and this could be interpreted within the "entatic state" principle which is used in coordination chemistry, catalysis, and bioinorganic chemistry. In this new hypothesis, the coordination of a cation by several anions with different properties can modify the local structure and it could enhance the electrochemical performance; this could be particularly useful for the future post-lithium batteries. The multianion approach can also be applied to electrolytes and interfaces. Finally, new theoretical calculations on multianion-based materials (carbonophosphates, thiocarbonates and Mg8Mn16O32-zFz) are reported here, highlighting the need for further research in the coordination sphere of metal-ligand systems for tuning battery properties.

Regulation of anionic structure and CO2 on the vesicle formation of imidazolium-based ionic liquids in water

The understanding of vesicle formation mechanism of ionic liquids (ILs) in aqueous solution is of great significance for the innovation and application of IL vesicles. In this work, a series of single-tailed amphiphilic ionic liquids (ILs) consisted of 1-tetradecyl-3-methylimidazolium [C14mim]+ and five kinds of anions have been designed to examine the regulation of anionic structures on the vesicle formation of ILs in water without any additives by surface tension, conductivity, cryogenic transmission electron microscopy, dynamic light scattering, small-angle X-ray scattering, and NMR spectroscopy. It is found that synergistic effect of hydrophobic and π-π interaction plays a vital role in the vesicle formation of 1-tetradecyl-3-methylimidazolium 1, 2, 3-benztriazole ([C14mim][1, 2, 3-Ben]). Interestingly, reversible structural transition between vesicle and micelle of this IL is observed by alternating CO2 and N2 bubbling due to the reversible formation of carbamate arising from the reaction between CO2 and the anion of the IL.

Viologen‐Based Uranyl Coordination Polymers: Anion‐Induced Structural Diversity and the Potential as a Fluorescent Probe

AbstractFour novel uranyl coordination polymers (CPs) have been synthesized by the utilization of viologen derivative ligand, 1,1’‐bis(3,5‐dicarboxyphenyl)‐4,4’‐bipyridinium (H4bdbp ⋅ 2Cl), and uranyl nitrate under hydrothermal reactions through the regulation of different kinds of inorganic acids (HF, HCl, HNO3, HClO4, H2SO4). Compound 1 features a unique triple‐stranded helix structure with a helical pitch of 31.578 Å. The ligands in compounds 2–4 have similar configurations, while their 3D structures are completely different due to the presence of different kinds of anions. The anions play different roles in the frameworks of these uranyl CPs. In addition, compound 2 possesses strong fluorescence both in solid‐state and aqueous suspension‐state. It is demonstrated that compound 2 can selectively detect Fe3+ over several competing metal cations in aqueous solution.

Corrosion behavior of Cu/Al casting-rolled clad plates in different alkaline solution

The effect of pH value and different kinds of anions on the corrosion behavior of Cu/Al casting-rolled clad plates in the alkaline solution was evaluated by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), weight loss analysis, 3D confocal laser scanning microscopy (CLSM) and electrochemical test. Results show the corrosion mainly occurs on the aluminum side. The corrosion resistance of the Cu/Al decreases as the pH value increases. When pH≥12, the dissolution of the film layer is faster than the passivation process. The addition of Cl− ions reduces the corrosion resistance of the Cu/Al clad plates, which leads to pitting corrosion. The higher the concentration of Cl− ions, the more prone the pitting to occur. The addition of SO42− ions causes the denudation of the samples. The corrosion resistance of the Cu/Al is better in the alkaline solution containing NO3− ions than that in the solution containing Cl− ions or SO42− ions. When adding SO42−, NO3− and Cl− to the pure alkaline solution, the corrosion resistance of the Cu/Al clad plates decreases.

Orthogonal chemistry in the design of rare-earth metal oxyhydrides

Abstract Inorganic systems containing two or more kinds of anions, such as rare-earth metal oxyhydrides, have a number of interesting properties that can be used in the design and development of new functional materials with desired characteristics. Chemical synthesis of these materials can be accomplished by oxidation of metal hydrides. However, the oxidation process of a metal hydride is directly accompanied by the release of hydrogen; both processes are a combination of two sequential reactions. This is usually not favorable for the formation and crystallization of the ternary oxyhydride composition. One possible way to overcome this problem is to introduce an appropriate amount of oxygen atoms into certain interstitial positions adjacent to the metal sites of the hydride lattice. Guided by the ideas of orthogonality, we have proposed a theoretical model capable of providing a thorough understanding of the chemical processes occurring in a multicomponent system at the molecular level. This model opens the way for predicting a wide range of new, stable multi-anion compounds of different compositions. It can also control functionality by adding noncovalent interactions between different kinds of anions, which can lead to the formation of chiral structures or a significant increase in ferro- and piezoelectric properties.

The defluorination of perfluorooctanoic acid by different vacuum ultraviolet systems in the solution.

Perfluorooctanoic acid (PFOA) is one kind of persistent organic pollutants that is often detected in water. In recent years, the effective degradation technologies of PFOA have attracted widespread attentions. Thus, in this study, the defluorination efficiency of PFOA in different systems (i.e., ultraviolet (UV), vacuum ultraviolet (VUV), vacuum ultraviolet/persulfate (VUV/PS) and vacuum ultraviolet/residual chlorine (VUV/RC)) was evaluated. Moreover, the different impact factors (i.e., the initial concentrations of persulfate and PFOA, temperature, anions, and initial pH values) on PFOA degradation by VUV/PS system were investigated. The results showed that VUV system was more effective than UV system for PFOA defluorination. VUV system combined with persulfate would further enhance the defluorination efficiency while residual chlorine would decrease it. In VUV/PS system, the defluorination efficiency of PFOA was the best as the molar ratio of PFOA and persulfate at 1:60. Moreover, higher temperature, lower initial PFOA concentration, and acid condition were favorable for the defluorination of PFOA. Under the different influence factors, the defluorination efficiency of PFOA fitted well to the first-order reaction kinetic model. When the temperature was range from 20°C to 40°C, the value of activation energy was 8.73kJ/mol. Besides, the inhibition effect of three kinds of anions on PFOA defluorination followed the order: >Cl- > . PRACTITIONER POINTS: The defluorination efficiency of perfluorooctanoic acid (PFOA) in water by different VUV systems was compared. VUV system is more effective than UV system for PFOA defluorination. Persulfate will enhance the defluorination efficiency by VUV system. Hypochlorite will decrease the defluorination efficiency by VUV system.

Transition metal pincer complex based self-healable, stretchable and transparent triboelecctric nanogenerator

As a promising energy converter, triboelectric nanogenerator (TENG) demonstrates unparalleled advantages. However, its performance is extremely affected by wear, tear and damage of the functional materials during triboelectrification. In this work, by incorporating tridentate pincer ligand moieties into a linear polydimethylsiloxane (PDMS) chain, the Zn-Pdca-PDMS elastomer for triboelectric layer was synthesized with excellent viscoelastic behaviors, super-stretchability (>5200%), self-healing ability and transparency. As a newly developed strategy, the strength of metal-ligand complex could be tuned efficiently by changing molar ratio of metal ions and ligands and three kinds of anions (CF3SO3−, BF4−, ClO4−) to adapt the desirable material performances. Subsequently, a stretchable, self-healable and transparent Zn-Pdca-PDMS based TENG (ZPP-TENG) was fabricated. With the molar ratio of Zn2+ to Pdca-PDMS ligand of 2:1, it exhibits the best output performance of 145 V, 6.7 nC cm−2 and 0.74 μA cm−2, respectively. The self-healable ZPP-TENG was employed as energy harvester to light up LEDs and charge a capacitor to driven electronic watch effectively. Even after several cutting-healing cycles, the output performance of the ZPP-TENG still maintain consistent. Finally, it was demonstrate to be employed a self-powered sensor for monitoring finger movement and pulse wave with excellent repeatability and stability.

Extraction of phenolic pollutants from industrial wastewater using a bulk ionic liquid membrane technique

ABSTRACT The academia and chemical industry are actively searching for alternative solvents to meet technology requirements since the most widely used solvents are harmful and volatile. For ionic liquids, there are several advantages over conventionally using organic membrane solvents, including high thermal stability, negligible vapour pressure, low volatility, etc. Here in this study, we have analyzed the abilities of ionic liquids as pure solvents as well as their binary mixtures, to recover phenolic compounds from the industrial wastewater. The field of phenol extraction from wastewater using ionic liquids remains less exposed, and we presume that the work of this kind would open up more and more opportunities for the scientific community as well as industrial people. Based on all these assumptions, the present work includes experimental data of a work which explains the possibilities of room temperature ionic liquids (RTILs) as potential bulk liquid membranes (BLM) for extracting phenol and other phenolic compounds from the industrial affluents. Four high hydrophobicity ionic liquids namely: 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [Bmim][NTf2], 1-butyl-3-methylimidazolium hexafluorophosphate [Bmim] [PF6] and 1-ethyl-3-methyimidazolium bis(trifluoromethanesulfonyl) imide [Emim][NTf2] were used for investigating the Phenol extraction efficiency and stripping efficiency. To provide a best comprehension of the influence of the phenolic structure as well as the nature of cation on the extraction ability of the ILs, we tried to understand the molecular interactions between the phenolic compounds and the solvents. The influence of hydrophobicity of ionic liquids and different kinds of anions on the extraction of phenol and efficiencies of stripping were investigated. All the experimental investigations performed here indicated that the only cation part of the ionic liquid is not an important aspect directly in this extraction, but the hydrogen bonding and the solute-solvent interactions play a significant role in the phenol removal process from aqueous phase to IL phase. First, the optimal conditions of operating (settling time and stirring) were analyzed for the clarity of the experiments performed. Concentration of NaOH in enhancing the performance of ionic liquids was also inspected here in this study. A binary mixture of ionic liquids (BMILs) membrane was examined for the optimized parameters, and the efficiency of phenol extraction was analyzed with the efficiency obtained for the single ionic liquid (SIL) membranes. The phenol concentration was determined by UV/visible spectrophotometer absorbance measurements. The highest phenol extraction efficiencies of 91% and 98.5%, were achieved by using [Bmim][NTf2] and [Bmim][NTf2+PF6] respectively, and the higher stripping efficiencies came up with 79% and 84% respectively, for [Emim][NTf2] and [Bmim + Emim][NTf2]. The results show that the binary mixture ionic liquid (BMIL) membrane is a better choice than single ionic liquid (SIL) membrane solvents. Hence, [Bmim] [(NTf2+PF6)] is an excellent selection as it provides high phenol stripping and extraction efficiencies with a minimal solvent loss and better stability in transport process.

Piperidinium and Pyrrolidinium Ionic Liquids as Precursors in the Synthesis of New Platinum Catalysts for Hydrosilylation

Six new air-stable anionic platinum complexes were synthesized in simple reactions of piperidinium [BMPip]Cl or pyrrolidinium [BMPyrr]Cl ionic liquids with platinum compounds ([Pt(cod)Cl2] or K2[PtCl6]). All these compounds were subjected to isolation and spectrometric characterization using NMR and ESI-MS techniques. Furthermore, the determination of melting points and thermal stability of the above derivatives was performed with the use of thermogravimetric analysis. The catalytic performance of the synthesized complexes was tested in hydrosilylation of 1-octene and allyl glycidyl ether with 1,1,1,3,5,5,5-heptamethyltrisiloxane. The study has shown that they have high catalytic activity and are insoluble in the reaction medium which enabled them to isolate and reuse them in consecutive catalytic cycles. The most active complex [BMPip]2[PtCl6] makes it possible to conduct at least 10 catalytic runs without losing activity which makes it an attractive alternative not only to commonly used homogeneous catalysts, but also to heterogeneous catalysts for hydrosilylation processes. The activity of the studied catalysts is also affected by the kind of anion and, to some extent, the kind of cation.

Molecular Basis of CLC Antiporter Inhibition by Fluoride.

CLC channels and transporters conduct or transport various kinds of anions, with the exception of fluoride, which acts as an effective inhibitor. Here, we performed sub-nanosecond DFT-based QM/MM simulations of the E. coli anion/proton exchanger ClC-ec1 and observed that fluoride binds incoming protons within the selectivity filter, with excess protons shared with the gating glutamate E148. Depending on E148 conformation, the competition for the proton can involve either a direct F-/E148 interaction or the modulation of water molecules bridging the two anions. The direct interaction locks E148 in a conformation that does not allow for proton transport, and thus inhibits protein function.

Energetic double salts based on 4,4′,5,5′-tetranitro-2,2′-biimidazolate

In the past few decades, energetic salts have been a growing interest in the development of new energetic materials, and a series of new energetic salts were synthesized. The traditional energetic salts are designed or synthesized by selecting one kind of anion and one kind of cation, thereby limiting the numbers of high energetic salts. In this paper, to increase the numbers of energetic salts, double salts based on 4, 4′, 5, 5′-tetranitro-2, 2′-biimidazolate (TNBI) were designed and their physical properties were accurately calculated, and one of the designed double salt of ammonium triaminoguanidinium 4, 4′, 5, 5′-tetranitro-2, 2′-biimidazolate ([A][TAG][TNBI]) was further synthesized and fully characterized. These studies not only provides a new way to design specific compounds, but also obtained some good high energy density materials with the detonation pressures ranging from 24.18 to 29.08 GPa, detonation velocities ranging from 7966 to 8637 m/s.

Building an electrochemical series of metals in pyrrolidinium-based ionic liquids.

An electrochemical series of pyrrolidinium-based ionic liquids is established by designing a redox system where only one kind of anion is present in the electrolyte and metal ions are supplied by anodic dissolution. This is the first report where an electrochemical series is established in pure ionic liquids.

Hofmeister Effect on Thermo-responsive Poly(N-isopropylacrylamide) Hydrogels Grafted on Macroporous Poly(vinyl alcohol) Formaldehyde Sponges

In this work, the Hofmeister effects of nine kinds of anions at different concentrations on the lower critical solution temperature (LCST) of the macroporous thermo-responsive poly(N-isopropylacrylamide) grafted poly(vinyl alcohol) formaldehyde (PVF-g-PNIPAM) hydrogels are investigated with differential scanning calorimetry (DSC). Four kinds of anions with strong hydration, including CO32–, SO42–, S2O32–, and F–, and four kinds of anions with weak hydration, including Br–, NO3–, I–, and ClO4–, and Cl– as a medium anion are systematically studied and found to demonstrate the effects of the residual hydroxyl groups and network structure of PVF on the LCST values of PVF-g-PNIPAM hydrogels in comparison with that of neat PNIPAM. On the one hand, the existence of hydroxyl groups on PVF backbone promotes the solubility of grafted PNIPAM due to their hydrophilicity and hydrogen-bond interactions with water. On the other hand, the network structure of as-prepared samples restricts free movements of grafted PNIPAM chains, which results in the increase of LCST values. In addition, the difference of grafting percentage also influences the variation of LCST values of PVF-g-PNIPAM hydrogels under salt concentration.

Effect of Copper Precursors on the Activity and Hydrothermal Stability of CuII−SSZ−13 NH3−SCR Catalysts

A series of CuII−SSZ−13 catalysts are prepared by in-situ hydrothermal method using different copper precursors (CuII(NO3)2, CuIISO4, CuIICl2) for selective catalytic reduction of NO by NH3 in a simulated diesel vehicle exhaust. The catalysts were characterized by X−ray diffraction (XRD), scanning electron microscope (SEM), X−ray photoelectron spectroscopy (XPS), N2 adsorption-desorption, hydrogen-temperature-programmed reduction (H2−TPR), ammonia temperature-programmed desorption (NH3−TPD), and 27Al and 29Si solid state Nuclear Magnetic Resonance (NMR). The CuII−SSZ−13 catalyst prepared by CuII(NO3)2 shows excellent catalytic activity and hydrothermal stability. The NO conversion of CuII−SSZ−13 catalyst prepared by CuII(NO3)2 reaches 90% at 180 °C and can remain above 90% at a wide temperature range of 180–700 °C. After aging treatment at 800 °C for 20 h, the CuII−SSZ−13 catalyst prepared by CuII(NO3)2 still exhibits above 90% NO conversion under a temperature range of 240–600 °C. The distribution of Cu species and the Si/Al ratios in the framework of the synthesized CuII−SSZ−13 catalysts, which determine the catalytic activity and the hydrothermal stability of the catalysts, are dependent on the adsorption capacity of anions to the cation during the crystallization process due to the so called Hofmeister anion effects, the NO3− ion has the strongest adsorption capacity among the three kinds of anions (NO3−, Cl−, and SO42−), followed by Cl– and SO42– ions. Therefore, the CuII−SSZ−13 catalyst prepared by CuII(NO3)2 possess the best catalytic ability and hydrothermal stability.

Preparation of Cu nanoparticle‐doped ZIF‐8/RGO composites for effective photodegradation of organic pollutant

Cu nanoparticle‐connected ZIF‐8/reduced graphite oxide (RGO) composite was successfully prepared through a facile hydrothermal reaction using sulfate in this paper. The crossover mechanism of metal nanoparticles loading and RGO decoration to enhance the photocatalytic efficiency of pristine ZIF‐8 was studied. The results showed that the prepared Cu‐S@ZIF‐8/RGO has a strong ability to take advantage of sunlight, indicating an appreciable application prospect. RGO can act as a base to support the whole structure and serve as an electron sink to accept photoexcited electrons, realizing the formation of reactive oxygen species (ROS) and inhibition of electron–hole pair recombination. Cu nanoparticles act as connectors between ZIF‐8 and RGO to transfer electrons and realize the formation of partial ROS on its surface. The doped sulfate radical can promote to extend the utilization of the wavelength range by generating surface states. Cu‐S@ZIF‐8/RGO showed the best photocatalytic activity in simulated sunlight for eliminating rhodamine B and 4‐chlorophenol among all the prepared samples, the structure kept intact even in the presence of different kinds of anions. The crossover study of metal loading and RGO decoration can develop a new way for only UV‐responsive metal–organic frameworks to remove organic contaminants under sunlight irradiation.

Syntheses and the crystal chemistry of the perfluoridotitanate(IV) compounds templated with ethylenediamine and melamine

Chemical reactions between ethane-1,2-diamine [C2H4(NH2)2; ethylenediamine, abbr. en] and 1,3,5-triazine-2,4,6-triamine [C3H6N6; melamine, abbr. mel], with titanium tetrafluoride (TiF4) were carried out in liquid anhydrous hydrogen fluoride (aHF). The latter acted in a dual role: as a reagent and as a solvent. The n(en): n(TiF4) = 2:1, 1:1, 1:3, 1:4, and n(mel): n(TiF4) = 2:1, 1:1, 1:2, 1:3, 1:4 M ratios were studied. Crystallizations of the products from the saturated HF solutions yielded single crystals of [enH2]F2·2HF, previously known [enH2][TiF6] and three new perfluoridotitanate(IV) salts, i.e., [enH2][TiF6]·HF, [enH2]0.5[TiF5] and [melH2][TiF6]·HF. Their crystal structures were determined including the crystal structure of the low-temperature modification of [enH2][TiF6]. The [enH2]0.5[TiF5] phase represents the first example of a structurally characterized perfluoridotitanate(IV) compound with a double charged cation, where instead of the usual octahedral [TiF6]2− monomer, another kind of anion is present, i.e., polymeric chain-like ([TiF5]−)∞ anion. The reactions in en/TiF4/HF and mel/TiF4/aHF systems are not selective enough to enable syntheses of individual [enH2]2+ and [melH2]2+ perfluoridotitanates(IV) in large quantities.

Anions influence the extraction of rutile nanoparticles from synthetic and lake water

Due to their recent widespread use, nanoparticles (NPs) may contaminate water sources and pose a health risk. Thus, it is important to understand the fate of NPs in order to evaluate potential threats. Here we show that the presence of anions influences the stability of NPs in synthetic and lake water. Concentrations of 0.3 and 3 mM PO43− exhibited stronger stabilizing effects on NPs than 30 mM. Moreover, chloride ions promoted the coagulation of TiO2 NPs over a range of concentrations (0.3–30 mM elicited similar effects). On the other hand, phosphate was found to hinder the coagulation effect. These results are expected to contribute to novel water purification strategies for the efficient removal of NPs. Further experiments should focus on the mechanism of phosphate on the removal of NPs in the coagulation/flocculation/sedimentation (C/F/S) process.