Iodide Ions In Solution Research Articles

Electrochemical Formation of Layered Organo-MnO2 and Its Application to Selective Iodide Recovery

We have fabricated a thin film of multilayered MnO2 whose interlayer is occupied with cetyltrimethylammonium cations (CTA+), using a simple anodic approach. X-ray diffraction (XRD) analysis and Fourier-transform infrared spectroscopy (FTIR) revealed that the deposited film possesses a layered structure of MnO2 and CTA molecules. The obtained film, CTA-intercalated layered MnO2 (CTA/MnO2), was applied as a sorbent toward iodide (I–). CTA/MnO2 film did not show significant iodide sorption from artificial seawater solution containing 0.1 mM NaI, but effectively sorbed iodide anions by excluding Ca2+ and HCO3 – from the artificial seawater solution, even in the presence of large amount of Cl– and SO4 2– anions. This indicates that Ca2+ and/or HCO3 – inhibit the uptake of iodide ions into the interlayer of CTA/MnO2. The sorption isotherm was in good agreement with the Langmuir type, and the maximum sorption capacity was estimated to be 213 mg/g-MnO2. Sorption of iodides into the interlayer of MnO2 film was evidenced by X-ray photoelectron spectroscopy (XPS). The results suggest that the sorption of iodide by the CTA/MnO2 film occur via not only simple ion-exchange, but also hydrophobic interaction between the interlayer organic phase of the film and iodide ions in solution. The layered structure of the CTA/MnO2 composite remained unchanged after the sorption experiment. Figure 1

Pyridine hydrazide glycoconjugate-based gelators: Facile synthesis and exploring their application in iodide sensing

Detection of iodide (I−) holds great importance because of its crucial role in various biological activities in the human body. However, its selective detection using small molecular systems has not been as well-explored as metal complex and metal-framework structures, which are expensive and difficult to synthesize. Here, we have reported the synthesis of a novel class of 4,6-O-protected sugar-pyridine hydrazide derivatives in an environmentally benign condition with moderate yield. The overall characterization was done using NMR, HRMS, single-crystal XRD, and DFT studies. Anomeric forms of the N-glucosylamines were assigned from NMR spectroscopy and single-crystal XRD studies. The selective sensing ability towards I− of the synthesized derivatives has been confirmed through colourimetry, UV–Vis and 1H NMR titration and gelation studies. The 4,6-O-butylidene derivatives 6(a–c) were utilized because of their better solubility for the selective detection of iodide ion in solution, whereas 4,6-O-benzylidene derivatives 7(a–c) were used for the same in gel state for their enhanced gelation ability. Furthermore, the morphology of the xerogels have been analyzed through SEM and the thermal ability has been determined by DSC spectra. The experimental studies suggest that the iodide anion takes part in self-assembly formation with the sugar-pyridine hydrazide derivatives through C–H···I− interaction, which, along with H-bonding, π–π stacking, van der Waal force of interaction enhances the gel formation.

Synthesis and characterization of Ag@Cu-based MOFs as efficient adsorbents for iodine anions removal from aqueous solutions

Due to the critical importance of capturing radioiodine from aquatic environments for human health and ecosystems, developing highly efficient adsorbent materials with rapid kinetics for capturing iodide ions in aqueous solutions is urgently needed. Although extensive research has been conducted on iodine adsorption in gas and organic phases, limited research has been dedicated to adsorption in aqueous solutions. An effective technique for removing iodide was proposed using Ag@Cu-based MOFs synthesized by incorporating Ag into calcined HKUST-1 with varying mass ratios of Ag/Cu–C. Extensive characterization using SEM, XRD, XPS, and nitrogen adsorption-desorption analysis confirmed successful incorporation of Ag in Cu–C. Batch adsorption experiments were conducted, demonstrating that the 5% Ag@Cu–C material exhibited a high adsorption capacity of 247.1 mg g−1 at pH 3. Mechanism investigations revealed that Cu0 and dissolved oxygen in water generate Cu2O and H2O2, while Ag and a small amount of CuO generate Ag2O and Cu2O. Furthermore, iodide ions in the solution are captured by Cu+ and Ag+ adsorption sites. These findings highlighted the potential of Ag@Cu-based MOFs as highly effective adsorbents for iodine anions removal in radioactive wastewater.

Retention of Iodide by Chloride Green Rust and Magnetite.

Green rust (GR), a layered double hydroxide (LDH) containing Fe, and magnetite can be found in natural and engineered environments. The ability of chloride GR (GR-Cl) and magnetite to retain iodide as a function of various parameters was investigated. Sorption equilibrium is achieved within 1 day of contact time between iodide and preformed GR-Cl in suspension. pHm variations (7.5-8.5) have no significant influence, but the iodide sorption decreases with increasing ionic strength set by NaCl. Sorption isotherms of iodide suggest that the uptake operates via ionic exchange (IC), which is supported by geochemical modeling. The short-range binding environment of iodide associated with GR is comparable to that of hydrated aqueous iodide ions in solution and is not affected by pHm or ionic strength. This finding hints at an electrostatic interaction with the Fe octahedral sheet, consistent with weak binding of charge balancing anions within an LDH interlayer. The presence of sulfate anions in significant amounts inhibits the iodide uptake due to recrystallization to a different crystal structure. Finally, the transformation of iodide-bearing GR-Cl into magnetite and ferrous hydroxide resulted in a quantitative release of iodide into the aqueous phase, suggesting that neither transformation product has an affinity for this anionic species.

Ozone Generation during High-Voltage Leak Detection: Fiction or Reality?

In order to further clarify if and how much ozone is generated during high-voltage leak detection and to identify measures to reduce the impact of ozone generation on product quality, a highly sensitive analytical system was employed to investigate the generation of ozone at different operational conditions of high-voltage leak detection integrity testing. The analytical system is based on oxidation of Iodide ions in solution and identification of the Iodine formed by N, N-Diethyl-p-phenylendiamine (DPD) according to DIN 38403. Sensitivity of the system was found suitable to detect ozone levels as low as 0.025 ppm (mg/L). High-voltage leak detection process parameters-inspection speed, high voltage, filling level of the ampoule, and exposure time to the ampoule to high voltage-were varied between maximum and minimum values applicable in integrity testing of different ampoule sizes. For variation of exposure time, ampoules were repetitively tested by the leak testing machine to achieve a maximum exposure time of the ampoule up to 24 s (exposure time during production ≤2.4 s). No ozone was detected during the study under all inspection conditions. Even repeated exposure of the ampoules to high-voltage leak detection did not result in generation of measurable ozone levels. It has to be concluded that high voltage leak detection is not prone to causing oxidation of the drug products.LAY ABSTRACT: For drug products in ampoules, 100% integrity testing is requested both by European and US regulations. Detection of integrity defects like small holes or cracks in the ampoule can be performed by numerous methods. Due to automation requirements, only three methods have been used during routine production-vacuum decay, head space infrared spectroscopy, and high-voltage leak detection. High-voltage leak detection is the most common method used in the pharmaceutical industry for 100% integrity testing of ampoules, but resent publications showed considerable oxidation of an air-sensitive active pharmaceutical ingredient during the integrity testing process. It was assumed that ozone generated in the inside of the vial due to exposure of the product to the high voltage during the testing process may be responsible for this result. As ozone is a very aggressive and non-selective oxidant, this result posed a serious thread not only to this product but also to the quality of many other products subjected to integrity testing by high-voltage leak detection.

Bimetallic Nanoparticles with Exotic Facet Structures via Iodide-Assisted Reduction of Palladium

Iodide is arguably the most challenging halide to control as a shape-directing additive in metal nanoparticle synthesis and the addition of iodide during bimetallic nanoparticle growth often leads to inhomogeneously stellated products. Through judicious control of low micromolar concentrations of iodide ions in solution in a seed-mediated approach, alloyed gold–palladium tetradecapod nanoparticles have been synthesized with a mixture of both well-defined convex and concave surfaces. Notably, these particles are uniform and symmetrical, and this unusual combination of convex and concave features in a single nanostructure is not simply an artifact of intersecting spikes, as would be the case with stellated particles. Further, an important new role for iodide in catalyzing the reduction of palladium ions is identified, particularly at the edge sites of the growing gold nanoparticles. This differs from the commonly accepted theory that iodide slows metal ion reduction, and thus opens up promising new routes to the synthesis of other bimetallic nanoparticles with exotic shapes and surface structures.

Synergistic interactions between tetra butyl phosphonium hydroxide and iodide ions on the mild steel surface for corrosion inhibition in acidic medium

The corrosion inhibitive action of tetra butyl phosphonium hydroxide (TBPH) on mild steel was investigated in 0.5M H2SO4. On adding the potassium iodide (KI) to the solution corrosion inhibition efficiency was significantly improved. The inhibitive action of TBPH was investigated at various inhibitor concentrations and at various temperatures; however, a synergistic improvement in the performance was seen when 10−3M KI was added to TBPH solution. Potentiodynamic polarization studies at various concentrations of TBPH and (TBPH+KI) inhibitor revealed that TBPH is a mixed type of inhibitor for mild steel in 0.5M H2SO4. Synergistic effect of TBPH and KI in corrosion inhibition of mild steel in 0.5M H2SO4 containing a low concentration of iodide ions has been evaluated by potentiodynamic polarization and the results suggest that the iodide ions in solution stabilized the adsorption of TBPH molecule on the metal surface and improved the inhibition efficiency of TBPH. The corrosion behavior of steel in 0.5M H2SO4 in the absence and with various concentrations of the inhibitor was studied from (298 to 328) K. It was found that the inhibition efficiency increases with inhibitor concentration and decreases with TBPH and (TBPH+KI) solution with an increase in temperature. Potentiostatic polarization study shows that TBPH and (TBPH+KI) are passivation type of inhibitor. The adsorption of TBPH is found to follow Frumkin adsorption isotherm whereas the adsorption of (TBPH+KI) follows the Temkin adsorption isotherm. Kinetic and thermodynamic parameters namely effective activation energy (Ea), and Gibbs free energy of adsorption (∆Goads) indicate that adsorption of TBPH and (TBPH+KI) on mild steel surface is primarily physical in nature. The results of scanning electron microscopy, atomic force microscopy, and quantum chemical analysis support the above inferences.

Studying Equilibrium in the Chemical Reaction between Ferric and Iodide Ions in Solution Using a Simple and Inexpensive Approach

A laboratory experiment on the study of the chemical equilibrium based on the reaction between ferric and iodide ions in solution with the formation of ferrous ions, free iodine, and triiodide ions is developed. The total concentration of iodide and triiodide ions in the reaction mixture during the reaction is determined by the argentometric titration; the concentrations of the other reagents and products are calculated using the material balance equations. The dependence of the equilibrium constant on temperature is also considered. The average values of Kc are 2.5 × 104 M–1 (35 °C) and 4.5 × 104 M–1 (45 °C). The experiment uses common reagents and simple equipment and can be performed in any educational laboratory. The basic procedure of processing the experimental data is quite simple and can be easily performed even by first-year students; however, the experiment can be extended in several ways to be suitable for advanced laboratory courses for upper-year undergraduates. Possible extensions are discus...

Selective sorption of iodide onto organo-MnO2 film and its electrochemical desorption and detection

This paper reports an electrochemically grown film consisting of layered MnO2 intercalated with hexadecylpyridinium cations (HDPy+), which can selectively sorb and detect iodide anions in aqueous solution amperometrically. Sorption of iodide by the HDPy/MnO2 film did not occur via ion exchange, but through hydrophobic interactions between the interlayer organic phase of the film and iodide ions in solution. The sorption rate increased with the deposited amount of MnO2. During the sorption process, the interlayer spaces expanded, and new diffraction peaks appeared that were attributed to the incorporated species. Anodic polarization of the iodide-sorbed HDPy/MnO2 film led to electron transfer from the incorporated iodide to the underlying substrate through the MnO2 sheets. The oxidized iodide was expelled from the film as molecular I2, while the expanded interlayer spaces were restored to their original state. Thus, the MnO2 layers and the incorporated HDPy can synergistically sorb/desorb iodide anions, resulting in a unique “self-cleaning” function that can operate electrochemically. This property allowed amperometric detection of iodide at a concentration as low as 0.0186μM, which was below the detection limits reported for previous iodide sensors.

Theoretical Studies on the Interaction of Ruthenium Sensitizers and Redox Couple in Different Deprotonation Situations

We report a DFT study of interaction between the Ru complex sensitizer [Ru(dcbpy)2(NCS)2: dcbpy = 4,4'-dicarboxy-2,2'-bipyridyl] (N3) and iodide ion under the influence of different deprotonation situations. There are two kinds of interaction mechanisms: iodide ion interacts with metal-center Ru atom or carboxyl, derived from the natural charge distribution analysis. The calculation indicated that there were several stable intermedium forms in different deprotonation degree. The stability of these intermedium forms would be perturbed gradually while the number of eliminated protons increased. It can be predicted that in the initial period of absorption and injection as well as the dissolve process where the deprotonation was demanded, the dye will not attacked by the iodide ion in solution extensively. Additionally, dye with more carboxyls will reduce the activity of redox reaction and more obstacles are required to be overcome before or during the redox reaction. The comparison of natural charge between isolate N3 and N3 with iodide ion intermedium (N3I(-)) showed the iodide ion attacking made the charge contribute on N3 molecule more negative, nevertheless the N3I(-) still has ability to attract another iodide ion. The attacking of iodide ion will also influence the electronic transition and absorption properties through the analysis of the frontier molecular orbitals and the densities of states. The results reported in this paper give us the guidance to carry out the further investigations about the dye regeneration process.

Corrosion Resistance of Metallic Substrates for the Fabrication Dye-Sensitized Solar Cells

A novel method of monitoring corrosion activity when an iodide/ triiodide dye-sensitized solar cell redox electrolyte is placed in contact with a range of metallic substrates is described. Corrosion of the metallic substrate results from anodic dissolution of the metallic surface coupled with cathodic reduction of triiodide (I3-) to colorless iodide ions in solution. In the work described here, UV/Vis spectrophotometry in reflectance mode is used in conjunction with encapsulation cells which incorporate a 25 microns thick electrolyte layer, prepared using a range of polished metallic substrates. The corrosion rate is quantified by monitoring changes in the absorption spectra with respect to time. Of the metals evaluated, only titanium was wholly resistant to corrosion and did not show evidence of reaction with the electrolyte for periods of up to 3 months. Other metals such as zinc reacted within seconds and complete and irreversible loss of I3- was observed after only a few minutes.

Highly sensitive determination of iodide by ion chromatography with amperometric detection at a silver-based carbon paste electrode

A silver-based solid carbon paste electrode was developed for use as a detector in ion chromatography (IC) for the sensitive determination of iodide in real samples. Micro- and nano-particles of silver were investigated for the fabrication of different electrodes. The iodide assay was based on IC with amperometric detection (IC-AD) at a silver composite electrode polarized at +0.080 V versus Ag/AgCl. Free iodide and organoiodide compounds were studied. The detection process was characterized by studying the redox behavior of iodide ions at both silver and silver composite electrodes by cyclic voltammetry (CV). The presence of iodide ions in solution was found to considerably facilitate metallic silver oxidation, with response currents directly related to iodide concentration. The calibration curve at the selected silver carbon paste electrode was linear in the concentration range comprised between 0.635 μg/L and 63.5 μg/L iodide. The relative standard deviation (R.S.D.) for successive injections was below 3% for all iodide standard solutions investigated. The limit of detection (LOD) was 0.47 μg/L (3.7 nmol/L) for an injection volume of 20 μL, i.e. 74 fmol injected. The IC-AD method was successfully applied to the determination of iodide in complex real samples such as table salts, sea products and iodide bound drug compounds. The analytical accuracy was verified by the assay of iodide in milk powder from an iodide certified reference material (CRM) Community Bureau of Reference (BCR) 150.

Halide ion determination from luminescence of the diprotonated form of porphyrin

We have studied quenching of the fluorescence of the diprotonated form of 3,7,13,17-tetramethyl-2,8,12,18-tetrabutylporphyrin by iodide ions in solutions. We have established that there is both static quenching of fluorescence when nonfluorescent complexes are formed with the iodide ions, as a result of an internal heavy atom effect, and also dynamic diffusion-controlled quenching. Based on analysis of the dependences of the fluorescence intensity and fluorescence lifetime on the iodide ion concentration in solution, we suggest using the diprotonated form of this porphyrin as the base compound for designing a fluorescent molecular receptor for halide ions.

Application of radiotracer technique to study the ion-isotope exchange reactions using a strongly basic anion-exchange resin duolite A-113

Short-lived radioactive 131I and 82Br tracers were used to study the kinetics of ion-isotope exchange reaction. The experiments were performed in the temperature range 26.0–43.0°C, ion concentration in solution in the range 0.0025–0.020 M, and amount of labeled ion-exchange resin varying from 0.250 to 1.250 g. For bromide ion-isotope exchange reactions, the calculated values of specific reaction rate, initial rate of bromide ion exchange, and amount of bromide ions exchanged were obtained higher than those for iodide ion-isotope exchange reactions under identical experimental conditions. The observed difference is attributed to the difference in the ionic size of bromide and iodide ions in solution.

Femtosecond dynamics of photodetachment of the iodide anion in solution: resonant excitation into the charge-transfer-to-solvent state

The photodetachment of iodide ions in solution is probed via ultrafast spectroscopy with ∼50 fs time resolution. Excitation of I− is achieved with a single photon at 255 nm, populating the quasi-bound charge-transfer-to-solvent (CTTS) state. The detached electron is trapped by the solvent within 200 fs. Electron–iodine recombination is observed to take place on ∼25 ps timescale, but a reasonable fraction of electrons escape geminate recombination beyond 400 ps. The dynamics of electrons generated from the I− CTTS state are compared with those arising from two-photon ionization of the neat solvents.

Sonochemical Oxidation of Iodide Ions in Solution Undersaturated with Ambient Gases

Sonochemical oxidation of I3- has been carried out in atmospheres of nitrogen, oxygen, air, and argon in the pressure range between 40 Torr and 760 Torr. The ambient gases have been dissolved by two methods: distillation and bubbling, with the former leading to undersaturation. Except for nitrogen, no simple relation exists between the reaction rates for the gas-undersaturated solutions, k U, and those for the gas-saturated solutions, k S. In some cases the values of k U are five times greater than those of k S in spite of the reversed order in the gas concentration.

Magnetic circular dichroism in the charge-transfer-to-solvent excited states of iodide ion in aqueous solution

Magnetic circular dichroism (MCD) spectra of iodide ions in solution are measured in the two resolved ultraviolet absorption bands that have been attributed to the charge-transfer-to-solvent (CTTS) excitation resulting in the iodine atom in 2P1/2 and 2P3/2 states. The relative absorption intensities and Faraday parameters of the twin bands in aqueous solution are theoretically reproduced with values of exchange interaction K = 500–600 cm-1 and spin-orbit coupling constant ζ = 5000 cm-1. A discrete variational (DV)-Xα molecular-orbital calculation is carried out for the [I(H2O)6]- ion, which is surrounded by a polarized dielectric continuum. This calculation reproduces the observed spectral parameters and leads to the conclusion that the lowest allowed transition of hydrated iodide ions in aqueous solution is to be ascribed to a Rydberg-type 5p → 6s excitation within the iodide ion, which gives rise to a charge transfer beyond the first solvation sphere (6·8a 0). However, the excitation yields no appreciable charge transfer far beyond the layer of oriented water molecules in immediate contact with [I(H2O)6]-.

Femtosecond studies of electron photodetachment from an iodide ion in solution: The trapped electron

We have performed femtosecond studies of electron photodetachment from a simple halide ion in aqueous solution. After photoexcitation, the electron is trapped in the deep potential well formed by the orientational polarization of the water molecules around the anion. This trapped state of the electron is a precursor of the wet electron and in the case of an aqueous iodide ion has a strong absorption in the visible. We hypothesize that the electron recombines with the neutral halogen atom or crosses onto the potential surface of the wet electron by a non-adiabatic electron transfer process. We find that analogous to the case of photoionization of a neutral water molecule, the wet to solvated electron transition in the vicinity of the halogen atom can be described as two-state in character.

The Equilibrium Between an AgBrxI1-xCrystal and the Aqueous Solution of its Ions

AbstractThe solubility of mixed silver halide crystals, AgBrxII-x, in excess of halogenides in solution has been calculated by summation of the concentrations of the different complex species in solution. The solubility curves for AgBrxII-x. crystals with x=0.95, 0.80, 0.65 are given for the temperatures T= 2C°C, 5C°C and 75°C. Additionally the concentrations of the [AgBr1P-J-complex and of the iodide ions in solution have been plotted relative to the concentration of dissolved silver as ' functions of pAg and temperature. The influence of the dominant species in solution upon the AgIcontent of a mixed silver halide is discussed.

Chronopotentiometry of solutions containing sodium iodide and iodine in dimethylsulphoxide

Chronopotentiometric waves of solutions of sodium iodide, and sodium iodide with added iodine in dimethylsulphoxide, were determined on platinum electrodes. Sodium perchlorate was used as supporting electrolyte. The concentration range was from 2 × 10−3 to 4 × 10−2 M and the temperature from 25·0 to 45·0°C.The anodic waves exhibit two well-defined steps characterized by definite transition times, while only one step is observed for the cathodic waves given by the solutions with added iodine. The cathodic waves are irreversible. The first anodic wave shows a larger irreversibility than the second. The results are discussed in comparison with previous information gathered for the same systems by employing a platinum rotating disk electrode.Diffusion coefficients for tri-iodide and iodide ions in solutions of DMSO obtained from chronopotentiometry are in agreement with those earlier reported derived from the rotating disk electrode.