Iodate Ions Research Articles

A selective resonance Rayleigh scattering method for determination of iodine by graphene oxide surface molecularly imprinted polyacrylamide probe

A new graphene oxide nanosurface molecularly imprinted polymer (GO@MIP) probe was synthesized by microwave irradiation, using graphene oxide (GO) as the carrier, iodine as the template molecule, acrylamide as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinking agent, azodiisobutyronitrile (AIBN) as the initiator, and acetonitrile as the pore forming agent. The nanoprobe recognizes the iodine, and exhibits significant resonance Rayleigh scattering energy transfer (RRS-ET) effect between iodine as the acceptor and the nanoprobe as donor. When iodine concentration was in the linear range of 0.02–0.5 mmol/L, the decreased RRS intensity was linear to the concentration. And it was used for the determination of iodine in water samples and iodate ions in salt samples.

Synthesis and Characterization of Iodinated Chitosan Nanoparticles and Their Effects on Cancer Cells.

The high degree of chemical modification of the chitosan chains due to protonated amine groups allows them to react with many negatively charged surfaces as anionic polymers and cell membranes, resulting in an attractive material for medical and pharmaceutics applications. Incorporating ionic iodine (I- and IO3 -) on chitosan chains is a direct way to successfully obtain chitosan-iodine nanoparticles (CSNPs-I and CSNPs-IO3) through ionic gelation. The nanoparticles (NPs) present a hemispherical morphology with sizes around 30-70 nm for CSNPs-I and CSNPs-IO3, similar to chitosan NPs, in accordance with SEM and DLS techniques. The XRD characterization did not show noticeable differences in the crystallinity index (CI) for CSNPs and CSNPs-I, 48.4 and 49.3%, respectively, but for CSNPs-IO3, the CI decreased to 43.85%. The cytotoxic effects on human tumor cells of chitosan and iodine-modified chitosan nanoparticles (CSNPs-I and CSNPs-IO3) were evaluated for 24 h in a range from 0.15 mg/mL to 0.95 mg/mL concentrations, where CSNPs-IO3 presented the lower viability for lung cancer A549, followed by cervical cancer HeLa cell and finally breast cancer MDA-MB-231, with a weight content of iodate ion in a range of 8.7 to 15 μg. This work presents the possibility of exploring chitosan-iodine NPs in medical applications.

Refining the carbonate-associated iodine redox proxy with leaching experiments

Iodate ions can substitute for carbonate in crystal lattices, which is why carbonate-associated iodine (CAI) is increasingly being used to track redox-sensitive iodine species, and by extrapolation, the redox conditions of ancient oceans. Extracting iodine from carbonate rocks is challenging, however, because iodine is susceptible to volatilization in acidic solutions. A broadly similar leaching scheme with different leaching times has been applied to all kinds of ancient carbonate rocks. However, the effects of non‑carbonate phases and iodine stability during leaching remain under-constrained, which limits its use for paleoredox reconstruction. For this study, we assessed these issues by conducting a series of leaching experiments on carbonate standards and ancient carbonate rocks of varying purity. We first developed an alternative stabilizer for iodine, i.e., 3% EDTA (ethylenediaminetetraacetic acid) in 3% NH4OH (ammonium hydroxide). This easily accessible new stabilizer effectively prevents the precipitation of metal ions from the alkaline solution, thus easing the preparation process and reducing the iodine signal drift during the CAI analysis. We also propose two interlaboratory limestone standards for iodine analysis with long-term (one year) I/Ca values of 0.43 ± 0.03 μmol/mol for limestone CRM-393 and 0.99 ± 0.06 μmol/mol for argillaceous limestone SRM-1c. Here we demonstrate that excessive leaching times (>60 min) can lead to the loss of nearly half of the iodine released under typical leaching conditions. Bulk carbonate digestion is shown to potentially underestimate primary CAI concentrations due to the presence of diagenetic carbonates. Moreover, we identified phosphates and organic matter as potential contaminants, the inadvertent leaching of which could lead to overestimated concentrations. Although the potential significance of such contamination warrants further study, our results show that contamination, if present, can be minimised by oxidative cleaning with 12% NaClO followed by dissolution in 0.3 M acetic acid. The possibility that measured CAI concentrations can be both under- and over-estimated may lead to reassessment of oxygenation events identified from the iodine concentrations of impure carbonate rocks.

Removal of Safranin O from Water by UV/TiO2/IO3− Advanced Oxidation Process: Parametric Study and Impact of Inorganic Ions and Humic Acid

In the present paper, the influence of iodate (IO3−) ions on the photocatalytic process using titanium dioxide (UV/TiO2) was systematically examined. The innovative studied system (UV/TiO2/IO3−) demonstrated high performance in the elimination of safranin O (SO), a model dye, from water due to the implication of iodine radicals (IO3•, IO2•, IO•, etc.). The degradation was assessed by monitoring the change in initial substrate concentration (5–30 mg∙L−1), TiO2 loading (0.01–3 g∙L−1), IO3− concentration, liquid temperature, and initial pH. Further enhancement of oxyanion amount was beneficial for the initial rate of degradation (r0) over the range 0.1–50 mM, such that r0 rose from 0.724 to 1.12 mg∙L−1∙min−1. However, a concentration of 100 mM IO3− slowed the removal kinetics. Low pH values were found to be favorable for pollutant removal. Furthermore, a variety of inorganic and organic substances was employed to clarify the effect of the UV/TiO2/IO3− process in natural waters. The findings revealed a negative impact of chloride excess in seawater and a decline in SO degradation in mineral water as a result of HCO3− presence at more than 1 mM. At high concentrations of natural organic matter, the heterogeneity and the strong adsorption of humic acid on the TiO2 surface were found to be harmful for SO decay.

Digital colorimetric sensor for assessment of iodate in food-grade salt based on paper-based analytical device

A digital colorimetric sensor was developed for the on-site measurement of iodate in food-grade salt. It involved a paper-based analytical device (PAD) containing an immobilized iodide/starch reagent and a smartphone as the detection system. Iodate ions produce a blue-black coloration on the PAD, the smartphone captures a digital image of the PAD, and an installed mobile app performs an analysis to generate color values related to the intensity of the color in the PAD. Parameters in the image acquisition and PAD preparation were optimized, and a matrix-matched calibration plot was employed for quantification. The plot exhibited a linear response in the concentration range of 10 to 100 mg iodate kg−1 of salt, and a detection limit of 2.20 mg kg−1 was determined. The present method was applied to analyze real samples, and the results agreed well with those obtained using the reference method at the 95% confidence level.

Efficient Iodine Removal by Porous Biochar-Confined Nano-Cu2O/Cu0: Rapid and Selective Adsorption of Iodide and Iodate Ions.

Iodine is a nuclide of crucial concern in radioactive waste management. Nanomaterials selectively adsorb iodine from water; however, the efficient application of nanomaterials in engineering still needs to be developed for radioactive wastewater deiodination. Artemia egg shells possess large surface groups and connecting pores, providing a new biomaterial to remove contaminants. Based on the Artemia egg shell-derived biochar (AES biochar) and in situ precipitation and reduction of cuprous, we synthesized a novel nanocomposite, namely porous biochar-confined nano-Cu2O/Cu0 (C-Cu). The characterization of C-Cu confirmed that the nano-Cu2O/Cu0 was dispersed in the pores of AES biochar, serving in the efficient and selective adsorption of iodide and iodate ions from water. The iodide ion removal by C-Cu when equilibrated for 40 min exhibited high removal efficiency over the wide pH range of 4 to 10. Remarkable selectivity towards both iodide and iodate ions of C-Cu was permitted against competing anions (Cl-/NO3-/SO42-) at high concentrations. The applicability of C-Cu was demonstrated by a packed column test with treated effluents of 1279 BV. The rapid and selective removal of iodide and iodate ions from water is attributed to nanoparticles confined on the AES biochar and pore-facilitated mass transfer. Combining the advantages of the porous biochar and nano-Cu2O/Cu0, the use of C-Cu offers a promising method of iodine removal from water in engineering applications.

Sunlight-activated periodate oxidation: A novel and versatile strategy for highly efficient water decontamination

This study reported for the first time that the sunlight-activated periodate (PI) system could appreciably boost the selective abatement efficiency of emerging organic contaminants from the aqueous environment. The sunlight/PI system completely removed bisphenol F after 30 min, which was slightly affected by multiple coexisting water constituents, suggesting its selective oxidation characteristics. This combined system could also eliminate other micropollutants under simulated or natural sunlight irradiation. Multiple lines of evidence demonstrated the production of different oxidizing intermediates such as singlet oxygen (1O2), hydroxyl radicals, and superoxide radicals. Among these species, 1O2 was convincingly deemed as the predominant oxidizing species contributing to the exceptional elimination of different micropollutants. Additionally, PI was stoichiometrically transformed into the unharmful iodate ion without forming other iodine species. Product analysis of three model pharmaceuticals (methotrexate, propranolol, and sitagliptin) signified that the proposed oxidation system could introduce the degradation products of plausibly enhanced biodegradability. Notably, 30 min of sunlight/PI treatment could also efficiently eliminate micropollutants from the highly saline water and accomplish prominent water disinfection. Overall, the major contribution of this investigation is to provide a novel, highly efficient, selective, green, and versatile oxidation strategy for sustainable water purification using the chemical-free natural activator.

Rapid Oxidative Dissolution of Metallic Tin in Alkaline Solution Containing Iodate Ions

Rapid Oxidative Dissolution of Metallic Tin in Alkaline Solution Containing Iodate Ions

Pressure-Driven Symmetry-Preserving Phase Transitions in Co(IO3)2

High-pressure synchrotron X-ray diffraction studies of cobalt iodate, Co(IO3)2, reveal a counterintuitive pressure-induced expansion along certain crystallographic directions. High-pressure Raman and infrared spectroscopy, combined with density-functional theory calculations, reveal that with increasing pressure, it becomes energetically favorable for certain I–O bonds to increase in length over the full range of pressure studied up to 28 GPa. This phenomenon is driven by the high-pressure behavior of iodate ion lone electron pairs. Two pressure-induced isosymmetric monoclinic–monoclinic phase transitions are observed at around 3.0 and 9.0 GPa, which are characterized by increasing oxygen coordination of the iodine atoms and the probable formation of pressure-induced metavalent bonds. Pressure–volume equations of state are presented, as well as a detailed discussion of the pressure dependences of the observed Raman- and infrared-active modes, which clarifies previous inconsistencies in the literature.

A method to distinguish halide ions by using a Briggs-Rauscher reaction

The current approach elaborates an innovative methodology for distinguishing four halide ions (F−, Cl−, Br− and I−) on their perturbation effects upon novel Briggs-Rauscher Reaction (BR) catalyzed by tetraaza-macrocyclic-nickel-complex (NiL)(ClO4)2. The lingand “L” in the complex is 5,7,7,12,14,14-hexamethyl-1,4,8,11 -tetraazacyclotetradeca-4,11-diene). Different oscillating profiles were exposed while the equal addition of four halide ions separately into active BR over the concentration range of 5.0 × 10−5-2.375 × 10−4 mol/L. Fluoride (F−) ion does not affect BR. Chloride (Cl−) ion could quench the potential oscillation at high potential and regenerate oscillation after a short inhibition time (tin). Bromide (Br−) ion could merely diminish the oscillation amplitude (A) and oscillation period (T) with no inhibition time whereas the iodate (I−) ion can restrain the potential oscillation at low potential and regenerate oscillation after a short inhibition time (tin). These four halide ions could be distinguished within 7 min. Cyclic voltammetry (CV) confirmed the redox reaction of potassium iodate with analytes while the bromination or the iodination products were testified by using mass spectrometry (MS) analysis after the perturbation of Br− or I−. Finally, a reasonable explanation of the perturbation mechanism for the BR was proposed based on well-known NF and FCA models.

Gel electromembrane microextraction followed by ion chromatography for direct determination of iodine in supplements and fortified food samples: Green chemistry for food analysis

In this study, a sensitive, selective, and environmentally friendly analytical method for direct extraction and preconcentration of iodine was developed. Iodine, as an iodate ion or iodide ion, was simultaneously extracted and preconcentrated by gel electromembrane microextraction (G-EME) and analyzed for total iodine by ion chromatography. The total iodine was determined by combining the peak areas of both iodate and iodide ions. Under the optimized conditions, linear calibration for iodine using a mixture of iodate and iodide ions was obtained from 10 to 100 µg L–1 (r2 > 0.996). The detection limit was 7.0 µg L–1. Recoveries of spiked iodine (as iodate) in the samples were greater than 90%. The method was applied for the determination of iodine in dietary supplements and fortified food samples, i.e., iodine-enriched eggs. Our developed method could be directly applied for the determination of iodine in different matrix samples including eggs without a pretreatment step.

Sources and hydrogeological conditions that cause high iodine concentrations in deep groundwater in the Zhangwei watershed, North China Plain

The sources and primary mechanisms of high iodine concentration in deep groundwater are rarely reported, thereby restricting the development and utilization of the related groundwater resources. To address these issues, 194 deep groundwater samples were collected from the Zhangwei watershed in the North China Plain, China, to analyze their constituents including iodine. Statistics, principal component analysis and hydrological methods were employed to determine the distribution of iodine concentrations and their controlling hydrogeochemical processes. The results show that the iodine concentration ranged from 2 to 446 μg/L and generally increased along the groundwater flow direction. Three zones with high iodine concentration (> 20 μg/L) were delineated as the alluvial–proluvial plain (Zone A, average 70 μg/L), alluvial–lake plain (Zone B, average 83 μg/L) and coastal plain (Zone C, average 199 μg/L), respectively. In Zone A, aquifer minerals weathering probably releases iodate ions into groundwater. The iodate is reduced with nitrate as the electron acceptor of iodine and transported with the precipitation infiltrating through the vadose zone to recharge groundwater, resulting in increasing the groundwater iodine concentration. In Zone B, the iodine concentrations depend on the contents of the organic matter, clay minerals, and iron aluminum oxide in the alluvial–lake sediments, due to that the deeply buried organic matter is rich in iodine which is released into groundwater through the biodegradation of organic matter, In Zone C, the iodine is probably derived from the sediments which were deposited in Quaternary marine transgression events, and its enrichment was controlled by the strong reduction condition of the deep aquifers. In one word, the iodine sources and hydrogeological conditions determined the high iodine concentrations of deep groundwater in the studied watershed. These findings can provide foundation for further insight into the high iodine concentration of deep groundwater in other hydrogeological units of the North China Plain and other similar units over the world, thereby ensuring drinking groundwater safety.

The reaction between iodide and iodate ions – a long lasting kinetic problem

AbstractZu den bekanntesten kinetisch untersuchten Reaktionen zählt die Reaktion zwischen Bromid und Bromat in saurer Lösung. Aufgrund der CMR‐Eigenschaften von Kaliumbromat gilt ein weitgehendes Verwendungsverbot in Schulen, so dass diese Reaktion im Unterricht nicht mehr experimentell untersucht werden darf. Hier wird als Alternative die Reaktion zwischen Iodid und Iodat in saurer Lösung vorgestellt. Es ergibt sich unter bestimmten Reaktionsbedingungen ein pentamolekulares Geschwindigkeitsgesetz.

Simple New Method for the Preparation of La(IO3)3 Nanoparticles.

We present a cost- and time-efficient method for the controlled preparation of single phase La(IO3)3 nanoparticles via a simple soft-chemical route, which takes a matter of hours, thereby providing an alternative to the common hydrothermal method, which takes days. Nanoparticles of pure α-La(IO3)3 and pure δ-La(IO3)3 were synthesised via the new method depending on the source of iodate ions, thereby demonstrating the versatility of the synthesis route. The crystal structure, nanoparticle size-dispersal, and chemical composition were characterised via angle- and energy-dispersive powder X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy.

Light intensity-dependence studies on the role of surface deposits for titania-photocatalyzed oxygen evolution: Are they really cocatalysts?

The effects of surface loading of iridium(II) oxide (IrO2), manganese(IV) oxide (MnO2), and cobalt(II) phosphate (CoPi) on the rate of photocatalytic oxygen evolution by anatase or rutile titania particles suspended in aqueous solutions of an electron acceptor, iodate ions, were studied by light intensity-dependence (LID) kinetic analyses. Although the role of these deposits has been reported to be a cocatalyst without showing results of any kinetic analysis, the present LID kinetic study suggested that the deposits may act as a "positive-hole capturer" for oxygen evolution, not as a cocatalyst for both metal oxides and CoPi. Further studies on the effects of loading amount, deposit types, titania crystalline type, and titania-particle size on the reaction order were also performed by LID analysis based on the proposed kinetic model. The observed LID behaviors could be interpreted consistently using a virtual parameter of "effective volume" as the target volume of photoabsorption by one positive-hole-bearing titania particle to govern the probability of two positive-hole accumulations in a titania particle.

Limits of stability in children diagnosed with Idiopathic Toe Walking

In the present study, a layer of titanium oxide nanotubes (TiO2NT) was formed by the electrochemical anodization of a titanium sheet (Ti) to produce TiO2NT/Ti. Then, palladium nanoflowers (PdNF) were deposited on the surface of a TiO2NT/Ti electrode by the photocatalytic reduction process. The characterization of TiO2NT/Ti and PdNF/TiO2NT/Ti was performed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) techniques. The PdNF/TiO2NT/Ti electrode proved to have catalytic activity for iodate ion (IO3−) reduction. As it was observed, the peak potential of iodate ion reduction at the surface of the PdNF/TiO2NT/Ti electrode shifted toward less negative values than that at the surface of a TiO2NT/Ti electrode. Through an amperometric method, three linear calibration ranges were obtained for iodate ion determination at the modified electrode surface. The detection limit calculated through the same method was 3.4 µM. Finally, the PdNF/TiO2NT/Ti electrode was put to use to determine iodate ions in a commercial salt sample, a nourishment supplement and a drinking water sample. The results were satisfactory.

Photochemical deposition of palladium nanoflowers on TiO2 nanotubes and their application for the electrocatalytic measurement of iodate ions

In the present study, a layer of titanium oxide nanotubes (TiO2NT) was formed by the electrochemical anodization of a titanium sheet (Ti) to produce TiO2NT/Ti. Then, palladium nanoflowers (PdNF) were deposited on the surface of a TiO2NT/Ti electrode by the photocatalytic reduction process. The characterization of TiO2NT/Ti and PdNF/TiO2NT/Ti was performed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) techniques. The PdNF/TiO2NT/Ti electrode proved to have catalytic activity for iodate ion (IO3−) reduction. As it was observed, the peak potential of iodate ion reduction at the surface of the PdNF/TiO2NT/Ti electrode shifted toward less negative values than that at the surface of a TiO2NT/Ti electrode. Through an amperometric method, three linear calibration ranges were obtained for iodate ion determination at the modified electrode surface. The detection limit calculated through the same method was 3.4 µM. Finally, the PdNF/TiO2NT/Ti electrode was put to use to determine iodate ions in a commercial salt sample, a nourishment supplement and a drinking water sample. The results were satisfactory.

Smartphone digital image colorimetry combined with solidification of floating organic drop-dispersive liquid-liquid microextraction for the determination of iodate in table salt

Smartphone digital image colorimetry (SDIC), combined with solidification of floating organic drop-dispersive liquid-liquid microextraction (SFOD-DLLME), was proposed for the determination of iodate ions. A colorimetric box was designed to capture images of sample solutions. Factors affecting the efficiency of SDIC included type of phone, region of interest, position of camera, and distance between camera and sample solution. Optimum SFOD-DLLME conditions were achieved with 1-undecanol (500 µL) as the extraction solvent, ethanol (1.5 mL) as the disperser solvent within 20 s extraction time. Limit of detection (LOD) was found as 0.1 µM (0.2 µg g−1) and enrichment factors ranged between 17.4 and 25.0. Calibration graphs showed good linearity with coefficients of determination higher than 0.9954 and relative standard deviations lower than 5.6%. The proposed method was efficiently applied to determine iodate in table salt samples with percentage relative recoveries ranging between 89.3 and 109.3%.

Dynamics of Water in the Solvation Shell of an Iodate Ion: A Born-Oppenheimer Molecular Dynamics Study.

The iodate ion has an anisotropic structure and charge distribution. It has a pyramidal shape with the iodine atom located at the peak of the pyramid. The water molecules interact differently with the positively charged iodine and the negatively charged oxygen atoms of this anion, giving rise to two distinct solvation shells. In the present study, we have performed ab initio Born-Oppenheimer molecular dynamics simulations to investigate the dynamics of water molecules in the iodine and oxygen solvation shells of the iodate ion and compared the behavior with those of the bulk. The dynamics of water is calculated for both the BLYP and the dispersion-corrected BLYP-D3 functionals at room temperature. The dynamics of water in the solvation shells at higher temperatures of 353 and 330 K has also been investigated for the BLYP and BLYP-D3 functionals, respectively. The hydrogen bond dynamics, vibrational spectral diffusion, orientational and translational diffusion, and residence dynamics of water molecules in the two solvation shells are looked at in the current study. The ion-water hydrogen bond dynamics is found to be somewhat faster than that for water-water hydrogen bonds in the bulk, which can be attributed to a ring-like electron distribution on the iodate oxygens. The dynamical trends are connected to the water structure making/breaking properties of the positively charged iodine and negatively charged oxygen sites of the anion. Furthermore, orientational jumps of the iodate ion and also those of surrounding water molecules which are hydrogen bonded to the oxygen atoms of the iodate ion are also investigated. It is found that the nature of these orientational jumps can be different from those reported earlier for planar polyoxyanions such as the nitrate ion.

Heterogeneous anion exchange membranes with nitrate selectivity and low electrical resistance

Selective transport of specific ions across ion-exchange membranes can be enhanced by controlling membrane properties such as hydrophobicity. Previous studies have shown that hydrophobic membranes enhance transport of ions with low hydration energy, although such membranes often have increased electrical resistance. In the present work, we study the separation of monovalent ions, specifically nitrate and chloride, using newly-designed heterogeneous anion-exchange membranes. These membranes show high selectivity for nitrate over chloride and have low electrical resistance. We use a functionalized polymeric binder (ionomer) and three ion-exchange resins with different hydrophobic groups, i.e., resins with quaternary ammonium groups and methyl, ethyl, and propyl substituents, respectively. We find that in electrolyte solutions with nitrate and chloride, nitrate over chloride selectivity in our membranes increases with increasing length of the alkyl groups. The membrane with propyl groups, i.e., which has the highest selectivity for nitrate, was further tested in electrolyte solutions containing nitrate, chloride, sulfate, and nitrate, chloride, iodate. The transport of sulfate and iodate ions across the membrane with propyl groups was 6% and 2% of the total counterions transport, respectively. For monovalent ions with similar hydrated size it is possible to report selectivity trends based on the ion hydration energy. We find that the chemical structure of the membrane can either promote or hinder the transport of ionic species.