Effect of Inorganic Ions on the Oxidation of Methyl Violet with Gliding Arc Plasma Discharge

Gliding arc discharge process was used for the treatment of methyl violet wastewater. First, the intermediate products were studied by gas chromatography coupled with mass spectrometry and Fourier transform infrared spectrometry, and ultraviolet–visible spectrometer. Second, the effects of inorganic anions including chloride (Cl^?), carbonate (CO₃ ^2?), sulfate (SO₄ ^2?), phosphate (PO₄ ^3?), nitrate (NO₃ ^?) on the degradation efficiency of methyl violet were examined. The research results indicated that hydroxyl radicals attacked carbon atom that situated in the center of dye molecule, and the conjugating structure of methyl violet was destroyed, and dye was degraded and decolored, so a possible degradation pathway was proposed by the analysis of intermediate products detected. The methyl violet degradation rate decreased with increasing anions concentrations, and their order of sequence according to the inhibition reaction was CO₃ ^2? > Cl^? > SO₄ ^2? > NO₃ ^?.     

Ion-exchange properties of microdispersed sintered detonation nanodiamond

The adsorption of transition metal cations and inorganic anions from aqueous solutions on microdispersed sintered detonation nanodiamond (MSDN) is systematically studied. The selectivity series Fe³⁺ > Al³⁺ > Cu²⁺ > Mn²⁺ > Zn²⁺ > Cd²⁺ > Co²⁺ > Ni²⁺ with maximum adsorption capacity between 2 and 5 µmol g^?1 is obtained. It is found that anions may significantly contribute to the adsorption of transition metal cations, so the adsorption of CH₃COO^?, Cl^?, B₄O₇ ^2?, ClO₄ ^?, I^?, SO₄ ^2?, C₂O₄ ^2?, PO₄ ^3? is also studied. For the first time, dominating adsorption of anions over cations is demonstrated for detonation nanodiamond. The maximum anion-exchange capacity of 50–150 µmol g^?1 is found for MSDN. Beside of electrostatic interactions, the formation of complexes with hydroxyl groups and interaction with metal impurities contribute to the adsorption of B₄O₇ ^2? and PO₄ ^3?, respectively. Therefore, anion exchange selectivity of MSDN is different from that observed for common anion exchange resins. In all cases, the adsorption on MSDN obeys Langmuir law. The pH effect on the adsorption of SO₄ ^2?, PO₄ ^3? and B₄O₇ ^2? is different from that observed for other anions due to specific interactions.     

Highly Selective Thiocyanate Electrode Based on Bis‐bebzion Schiff Base Binuclear Copper(II) Complex as Neutral Carrier

Abstract

A highly selective polyvinyl chloride (PVC) membrane electrode, based on N,N′‐(aminoethyl)ethylenediamide bis(2‐benzoideneimine) binuclear copper(II) complex [Cu(II)‐AEBB] as neutral carrier, was prepared for thiocyanate (SCN^?) determination, which displays an anti‐Hofmeister selectivity sequence for a series of anions in the following order: SCN^?>ClO₄ ^?>Sal^? > I^?>NO₃ ^?>Br^?> Cl^?>NO₂ ^?>SO₃ ^2?>F^?>H₂PO₄ ^?>SO₄ ^2?. The electrode exhibited near‐Nernst response for SCN^? with a slope of –59.0 mV/decade over a wide concentration range (8.5×10^?7～6.8×10^?1 mol/L) with a detection limit of –5.0×10^?7 mol/L in pH 5.0 phosphate buffer solution at 25°C. Alternating current (AC) impedance and equivalent circuits were used to investigate the thiocyanate response mechanism of the membrane doped with [Cu(II)‐AEBB].     

Ion Chromatographic Determination of Anions in Environmental Samples

Abstract

The use of ion-exchange chromatography with an IonPac AS 14 column, 3.5 mM Na₂CO₃/1.0 mM NaHCO₃ eluent and suppressed conductivity detection provides a simple, cost-effective, fast, accurate, and highly sensitive method for the determination of F^?, Cl^?, NO₂ ^?, Br^?, NO₃ ^?, PO₄ ^2?, SO₄ ^2?, and C₂O₄ ^2? at low μ/L levels in environmental samples. Data on sensitivity, selectivity, accuracy, and % relative standard deviation are described. The method is suitable for many environmental applications including atmospheric aerosols (exposed on cellulose, glass fiber, and quartz filters), rainwater, cloud water, potable- and non-potable waters, and carbonated waters. Dominant components of the aerosol were SO₄ ^2?, NO₃ ^?, and Cl^?. Rainwater, on the other hand, has relatively very low concentrations of these three species. The wide-spread concentration range for Cl^? in variety of water samples and the high concentrations for SO₄ ^2? in drinking water are striking. Determination of the anionic composition of carbonated waters revealed a considerable variation of the individual anions.     

The Cloud Point Behaviors and the Liquid–Liquid Equilibrium of L31—Inorganic Sodium Salt Aqueous Two-Phase Systems

The cloud point (CP) of triblock-copolymer L31 aqueous solution was determined with salting-out salts (Na₂SO₄/Na₂CO₃/NaF/NaCl/NaBr). The results show that all these salts can decrease the CP of L31 aqueous solution and form aqueous two-phase system (ATPS). With increasing concentrations of Na₂SO₄ and Na₂CO₃, an obvious phase inversion could be observed and phase inversion points were found. This was mainly due to the change in density, the salt-rich phase shifted from the top phase to the bottom phase. Meanwhile, the liquid-liquid equilibrium (LLE) data for L31-Na₂SO₄/Na₂CO₃/NaF/NaCl/NaBr ATPSs were measured at 288.15 K. The salt ability to decrease the CP and to induce the phase separation is as follows: Na₂SO₄?>?Na₂CO₃, NaF?>?NaCl?>?NaBr. Finally, the order of anions that reduced the CP and caused phase separation was obtained as follows: SO₄^2? >CO₃^2?, F^??>?Cl^??>?Br^?.     

Drawing Out the Structural Information About the First Hydration Layer of the Isolated Cl− Anion Through the FTIR-ATR Difference Spectra

The Fourier transform infrared-attenuated total reflectance (FTIR-ATR) difference spectra of aqueous MgSO₄, Na₂SO₄, NaCl and MgCl₂ solutions against pure water were obtained at various concentrations. The difference spectra of the solutions showed distinct positive bands and negative bands in the O–H stretching region, indicating the influences of salts on structures of hydrogen-bonds between water molecules. Furthermore the difference spectra of MgCl₂ solutions against NaCl solutions and those of MgSO₄ solutions against Na₂SO₄ solutions with the same concentrations of anions (Cl^? or SO ₄ ^2? , respectively) allowed extracting the structural difference of the first hydration layer between Mg²⁺ and Na⁺. Using SO ₄ ^2? as a reference ion, structural information of the first hydration layer of the Cl^? anion was obtained according to the difference spectra of MgCl₂ solutions against MgSO₄ solutions and those of NaCl solutions against Na₂SO₄ solutions containing the same concentrations of cations (Mg²⁺ or Na⁺, respectively). The positive peak at ~3,407 cm^?1 and negative peak at ~3,168 cm^?1 in these spectra indicated that adding Cl^? decreased the strongest hydrogen-bond component and increased the relatively weaker one.     

Dichlorphosphatokomplexe der Nitridchloride von Molybdän und Wolfram

Dichlorophosphate Complexes of the Nitrido Chlorides of Molybdenum and Tungsten Tetraphenylarsonium dichlorophosphate AsPh₄[PO₂Cl₂], is prepared by the reaction of AsPh₄Cl with P₂O₃Cl₄. The vibrational spectrum is reported as well as the valence force constants of the [PO₂Cl₂]^? ion. The f-values are clearly smaller than those of the isoelectronic SO₂Cl₂ molecule. The dichlorophosphate ion forms complexes with the nitride chlorides MNCl₃ (M ? Mo, W) of the type [MNCl₃(PO₂Cl₂)]₂^2?, which are characterized by their i.r. spectra.     

The Determination of Non-Oxidizable Species Using Electrochemical Detection in Ion Chromatography

Abstract

The use of an electrochemical detector for the ion chromatographic detection of non-oxidizable anions such as F^?, PO₄ ^?3, NO₃ ^?, and SO₄ ^?2 is described. The electrochemical detector is placed in line after a fiber suppressor and responds to eluent pH changes as the dissociated acids pass through the detector. The intensity of the signal is dependent on the applied potential at the cell with 0.3V being an optimum. Minimum detection limits with a 0.10 mL sample injection volume are below 0.5 ppm for F^?, Cl^?, PO₄ ^?3, NO₃ ^?, and SO₄ ^?2. No adverse effects on the silver working electrode have been observed.     

Thermal properties of sulfonic acid group functionalized Brönsted acidic ionic liquids

Thermal decomposition onset temperatures have been measured for a total of 24 methylimidazolium, triethanolammonium, and pyridinium type sulfonic acid groups functionalized Brönsted acidic ionic liquids with Cl^?, Br^?, SO₄ ^2?, PO₄ ^3?, BF₄ ^? _, CH₃CO₂ ^?, and CH₃SO₃ ^? anions, using thermogravimetric analysis. Thermal stabilities of these sulfonic acid group functionalized ionic liquids decreases in the order, methylimidazolium > triethanolammonium > pyridinium. The methylimidazolium, pyridinium, and triethanolammonium ionic liquids investigated showed decomposition onset temperatures (air) in the 213–353, 167–240, and 230–307 °C ranges, respectively. Additionally, the decomposition temperatures of these ionic liquids are highly dependent on the nature of the anion.     

ESR-Untersuchungen an μ-Dichloro-bis[chloro-bis(N,N-diäthyldiselenocarbamato)molybdän(V)]-dichlorid, [Mo2CI4(däsc)4]CI2

EPR-Investigations of α-Dichloro-bis[chloro?bis(N,N?diethyldiselenocarbamato)molybdänum(V)] dichloride, [Mo₂Cl₄(däsc)₄]Cl₂. Preparation and bonding properties of the coordination sphere of [Mo₂Cl₄(däsc)₄]Cl₂ studied by EPR, are reported. The EPR-spectrum at 77°K can be described by an axial symmetric spin-HAMILTONian, the parameters of which are g| = 2.046, g|= 1.996, A| = 53.5 · 10^?4 cm^?1, and A| = 22.8 · 10^?4 cm^?1. No ⁷⁷Se-ligand hyperfine structure could be observed. The very high g-values are explained as being caused by strong ligand spin-orbit interaction, CT-contributions and a high degree of co valency of tho Mo? Se bond. Using an MO-model of the symmetry C_4v, the bonding parameters of the first coordination sphere have been calculated.     

Host–Guest Chemistry: Oxoanion Recognition Based on Combined Charge‐Assisted C−H or Halogen‐Bonding Interactions and Anion⋅⋅⋅Anion Interactions Mediated by Hydrogen Bonds

Several bis‐triazolium‐based receptors have been synthesized and their anion‐recognition capabilities have been studied. The central chiral 1,1′‐bi‐2‐naphthol (BINOL) core features either two aryl or ferrocenyl end‐capped side arms with central halogen‐ or hydrogen‐bonding triazolium receptors. NMR spectroscopic data indicate the simultaneous occurrence of several charge‐assisted aliphatic and heteroaromatic C?H noncovalent interactions and combinations of C?H hydrogen and halogen bonding. The receptors are able to selectively interact with HP₂O₇^3?, H₂PO₄^?, and SO₄^2? anions, and the value of the association constant follows the sequence: HP₂O₇^3?>SO₄^2?>H₂PO₄^?. The ferrocenyl end‐capped 7²⁺?2 BF₄ ^? receptor allows recognition and differentiation of H₂PO₄^? and HP₂O₇^3? anions by using different channels: H₂PO₄^? is selectively detected through absorption and emission methods and HP₂O₇^3? by using electrochemical techniques. Significant structural results are the observation of an anion???anion interaction in the solid state (2:2 complex, 6²⁺? [ H₂P₂O₇ ] ^2? ), and a short C?I???O contact is observed in the structure of the complex [ 8 ²⁺][SO₄]_0.5[BF₄].     

Solid‐Liquid Equilibria in the Quinary Na+, K+//Cl−, SO2−4, B4O2−7‐H2O System at 298 K

The solid‐liquid equilibria in the quinary system Na⁺, K⁺//Cl^?, SO^2?₄, B₄O^2?₇‐H₂O at 298 K had been studied experimentally using the method of isothermal solution saturation. Solubilities and densities of the solution of the quinary system were measured experimentally. Based on the experimental data, the dry‐salt phase diagram and water content diagram of the quinary system were constructed, respectively. In the equilibrium diagram of the quinary system Na⁺, K⁺//Cl^?, SO^2?₄, B₄O^2?₇‐H₂O at 298 K, there are five invariant points F1, F2, F3, F4 and F5; eleven univariant curves E1F1, E2F2, E3F3, E4F5, E5F2, E6F4, E7F5, F1F4, F2F4 F1F3 and F3F5, and seven fields of crystallization saturated with Na₂B₄O₇ corresponding to Na₂SO₄, Na₂SO₄·10H₂O, Na₂SO₄·3K₂SO₄ (Gla), K₂SO₄, K₂B₄O₇·4H₂O, NaCl and KCl. The experimental results show that Na₂SO₄·3K₂SO₄ (Gla), K₂SO₄ and K₂B₄O₇·4H₂O have bigger crystallization fields than other salts in the quinary system Na⁺, K⁺//Cl^?, SO^2?₄, B₄O^2?₇‐H₂O at 298 K.     

Einbau von Na2SO4 in die Hochtemperaturform des Na3PO4

Formation of Solid Solutions of Na₂SO₄ in the High-temperature Form of Na₃PO₄ The high-temperature form of Na₃PO₄ solves up to 70 mole-% Na₂SO₄ maintaining the type of crystal structure. The lattice constants increase from 742.3(1) pm (pure Na₃PO₄) to 749.1(2) pm for Na^3?x(PO₄)^?x(SO₄)_x (x = 0.7). The high-temperature form, in the case of pure Na₃PO₄ stable above 325°C, is stabilized at room-temperature by doping with small amounts of Na₂SO₄.     

Base hydrolysis of (αβ S)-(o-methoxy benzoato) (tetraethylenepentamine) cobalt(III) ion: A comparative study of the role of ion pairs and micelles

The kinetics of base hydrolysis of (αβ S)-(o -methoxy benzoato) (tetraethylenepentamine)cobalt(III) obeyed the rate law: k_obs = k_OH[OH^?], in the range 0.05 ? [OH^?]_T, mol dm^?3 ? 1.0, I = 1.0 mol dm^?3, and 20.0–40.0°C. At 25°C, k_OH = 13.4 ± 0.4 dm³ mol^?1 s^?1, ΔH^≠ = 93 ± 2 kJ mol^?1 and ΔS^≠ = 90 ± 5 JK^?1 mol^?1. Several anions of varying charge and basicity, CH₃CO₂^?, SO₃^2?, SO₄^2?, CO₃^2?, C₂O₄^2?, CH₂(CO₂)₂^2?, PO₄^3?, and citrate^3? had no effect on the rate while phthalate^2?, NTA^3?, EDTA^4?, and DTPA^5? accelerated the process via formation of the reactive ion pairs. The anionic (SDS), cationic (CTAB), and neutral (Triton X-100) micelles, however, retarded the reaction, the effect being in the order SDS> CTAB > Triton X-100. The importance of electrostatic and hydrophobic effects of the micelles on the selective partitioning of the reactants between the micellar and bulk aqueous pseudo-phases which control the rate are discussed. © 1994 John Wiley & Sons, Inc.     

Kinetic Studies on the Oxidation of Germanium(II) with Chlorate by Polarographic Analysis

The rate of oxidation of Ge(II) chloride by large excess of ClO₂^? ions in HCl, NaCl and Na₂SO₄ mixed solutions was polarographically observed at various H₂O⁺ and Cl^? ion concentrations. The observed rate constant, k_obs, is expressed by k_o=K_obs/(ClO₃^?)={k₁,(H⁺)+k₂K₁(Cl^?)²+ K₃K₂(SO₄^2?)} (H⁺)/{(H⁺)¹+K₁(Cl^-)2 +K₂(SO₄^2?)} for the following reaction processes, The values were obtained aa k₁=1.5410^-3liter² mole^2? sec^-1, k₂=5.00×10^-2liter² mole^2? sec^-2 and k₂=4.30×10^-3liter² mole^2? sec^-2, K₁=1.80× 10^-2, K₂= 2.43×10^-2 mole liter^-1 at constant ionic strength I=0.50 M at 30°C.     

Bulk Acoustic Wave Sensor for Non-suppressed Ion Chromatographic Determination of Nitrate and Other Inorganic Anions in Vegetables

Abstract

A new type of bulk acoustic wave sensing device based on a conductivity-bulk acoustic wave frequency response is applied in ion chromatography to determine nitrate and other inorganic ions in vegetables. The present method has the advantages in its rapidity, simplicity, sensitivity and accuracy. Detection limits (peak=3[sgrave]) are obtained for NO₃ ^?, Cl^?, NO₂ ^?, H₂PO₄ ^? and SO₄ ^2? at concentrations of 1, 0.6, 1, 7 and 3 ng (on column), respectively. Neither derivatization nor a clean-up step is necessary besides filtration. For the IC analysis, the analytical column is a Shim-pack IC AI column, and the eluent is 2.0 mM phthalic acid solution with pH 4.0. A comparison of IC-SBAW with conventional IC is made. The method allows the simultaneous determination of nitrate and other inorganic ion levels in vegetables.     

Effect of anions on the dissolution of Al in acid solutions

The effect of Cl^?, Br^?, I^?, ClO₄^?, NO₃^?, HSO₄^?, HCrO₄^? and H₂PO₄^? on the of Al in 2 M HCl is studied by the thermometric method. Three sets of experiments are carried out, which allow the variation of the concentration of the various species in a programmed manner. Dissolution promotion is noted in solutions to which HCl, HBr and H₂CrO₄ are added. The way of action of each of these anions is discussed. Additions of HI, HClO₄, H₂SO₄ and H₃PO₄, on the other hand, first retard and later enhance the dissolution of Al in 2 M HCl, as their concentration in solution is increased. This is related to anion adsorption, which is counterbalanced by increase in acidity. HNO₃ differs from the other tested acids in causing only dissolution retardation. Experiments in which LaCl₃ is added to the test solution indicate that the NO₃^? is adsorbed as such on Al₂O₃. The ability of the various anions to retard the dissolution of Al in 2 M HCl decreases in the succession: NO₃^? (strong)>I^?>HSO₄^?>H₂PO₄^?>Br^?, ClO₄^? (weak)     

Adsorption phenomena on polycrystalline gold electrode modified by Zn adatoms

Summary In this paper, experimental results obtained by the in-situ radiotracer and voltammetric studies of the competitive adsorption of the HSO₄^-/SO₄^2- (labeled with ³⁵S) and Cl^- (labeled with ³⁶Cl) anions on bare Au_poly substrate and Au_poly surfaces modified by the Zn adatoms in the lower pH region (pH≤4.5) are presented and discussed. In addition, some data on the formation of Zn adlayers (labeled with ⁶⁵Zn) are reported to demonstrate the complex features of the underpotential deposition (UPD) phenomenon. It has been revealed that (1) the relative adsorption strength of Cl^- ions on bare Au_poly is higher than that of H₂PO₄^-/PO₄^3- and HSO₄^-/SO₄^2- ions in the entire pH region studied; (2) anomalous tendency of the specific adsorption of anions on polycrystalline gold modified by Zn adatoms occurs at pH 4.5 as follows: PO₄^3->SO₄^2->Cl^->>ClO₄^- and (3) the UPD of Zn²⁺ ions on polycrystalline gold is measurable even from solutions containing 5 ^. 10^-8M Zn²⁺ over the entire potential range where the hydrogen evolution takes place.It is, however, plausible to assume that the coverage of the gold surface by Zn adatoms measured even at solution concentrations of c≥5 ^. 10^-4M does not exceed one monolayer.     

Structure cristalline de (NH4)2PO3H,H2O: Stereochimie de l'Ion PO3H2− et ses relations avec PO3F2− et SO32−

(NH₄)₂PO₃H, H₂O crystallizes in the monoclinic system, space group P2₁/c, with a = 6.322(1) Å, b = 8.323(1) Å, c = 12.676(1) Å, β = 98.84(1) and Z = 4. The structure was refined to R = 0.022 based on 853 independent X-Rays intensities. Improved dimensions of the tetrahedral PO₃H^2? ion have been obtained: P?H = 1.34(2) and P?O = 1.514(2) Å. The geometry of this ion is compared with that of PO₃F^2? and SO₃^2? ions and we find a decrease of the volume: V_F? > V_H+ > V_{lone pair}.     

Thermal investigation of diamine complexes of Zn(II) in the solid state

The complexes [Zn(en)₃]X2·n H₂O, where en = ethylenediamine, X = Cl^?, Br^? or $\text{1}\text{2}$SO^2?₄, n = 1 or 0.5, and [Zn(tn)₂]X₂·n H₂O, where tn=1,3-diaminopropane, X=Cl^?, Br^? or $\text{1}\text{2}$SO^2?₄, n = 0 or 0.25, have been synthesized and their thermal investigations carried out. The complexes were characterized by elemental analysis and IR spectral data. These complexes have been observed to decompose through several isolable as well as non-isolable complex species as intermediates during heating. [Zn(tn)₂]SO₄ undergoes solid-state phase transition in the temperature range 126–145°C. ZnenSO₄ and ZntnX₂ (X = Cl^?, Br^? or $\text{1}\text{2}$SO^2?₄) have been synthesized pyrolytically in the solid state from their corresponding mother diamine complexes. ZnenSO₄ and ZntnX₂ (X = Cl^?, Br^? or $\text{1}\text{2}$SO^2?₄) complexes decompose through non-isolable hemidiamine species. ZnX₂ (X = Cl^? or Br^?) complexes of tn undergo melting after formation of the monodiamine species. In contrast, the corresponding en complexes undergo melting at non-stoichiometric composition. Diamine (en or tn) is found to be bridging in all monodiamine (en or tn) complexes; whilst their mother complexes possess chelated en or tn. The thermal stability sequence of en and tn complexes of Zn(II) is ZnCl₂ < ZnBr₂ < ZnSO₄. ΔH values are reported for some steps of decomposition. Possible mechanistic paths have been reported for each step of decomposition.