Reduction Of BrO3 Research Articles

Synthesis, structure and electrochemical properties of a new γ-octamolybdate-based 3D inorganic-organic hybrid containing scarce Mo-N bond

A new inorganic–organic hybrid based on γ-[Mo8O26]4–, Ni(bbi)2(bbi)0.5[γ-Mo8O26]0.5·H2O (1) (bbi = 1,1′-(1,4-butanediyl)bis(imidazole)), has been synthesized and structurally characterized by X-ray single-crystal diffraction. [Ni2(bbi)2(bbi)]4+ chains are linked into a 3D framework structure by γ-[Mo8O26]4–, in which γ-[Mo8O26]4– adopts μ4-coodination mode to chelate two Ni2+ through terminal oxygen atoms and two coordinate imidazole-N of bbi ligands via five-coordinated Mo atoms. The Hirshfeld surface analyses have been calculated. The electrochemical performances studies showed that the hybrid not only had bi-functional electrocatalytic activities toward the reduction of BrO3−/Fe3+/H2O2 and the oxidation of AA, but also had the amperometric sensor functions of BrO3−.

Degradation of carbamazepine in ice with bromate and nitrite: Role of reactive nitrogen species

Seasonal freezing of waters occurs during winter in cold regions. Bromate (BrO3–) is a disinfection by-product generated during water treatment, its interaction with emerging contaminants may be affected by freezing. Nitrite (NO2–) is widely distributed in the environment, whereas its effect on the interaction of emerging contaminants and BrO3– in ice may have been overlooked. Herein carbamazepine (CBZ) was selected as a model emerging contaminant to elucidate the role of reactive nitrogen species (RNS) in contaminant transformation during the reduction of BrO3– by NO2– in ice. Results indicated that freezing significantly enhanced CBZ degradation by BrO3–. The CBZ degradation by BrO3– and NO2– in ice was 25.4 %–27.8 % higher than that by BrO3–. Contributions of hydroxyl radical (•OH), bromine radical (•Br), and RNS to CBZ degradation in freezing/dark or sunlight systems were 8.1 % or 15.9 %, 25.4 % or 7.2 %, and 66.5 % or 76.9 %, respectively. Most CBZ was degraded by RNS generated during the reduction of BrO3– by NO2– in ice, resulting in 16.4 % of transformation products being nitro-containing byproducts. Hybrid toxicity of CBZ/BrO3–/NO2– system was reduced effectively after the freezing-sunlight process. This study can provide new insights into the environmental fate of emerging contaminants, BrO3–, and NO2– in cold regions.

Reduction of bromate by zero valent iron (ZVI) enhances formation of brominated disinfection by-products during chlorination

Bromate (BrO3−) is a predominant undesired toxic disinfection by-product (DBP) during ozonation of bromide-containing waters. The reduction of BrO3− by zero valent iron (ZVI) and its effect on formation of organic halogenated DBPs during chlorination were investigated in this study. The presence of ZVI could reduce BrO3− to bromide (Br−), and Br− formed could be transformed to free bromine (HOBr/OBr−) during chlorination, further leading to organic brominated (Br-) DBPs formation. Formation of DBPs during chlorination, including trihalomethanes (THMs) and haloacetonitriles (HANs) was detected under different conditions. The results showed that when ZVI dosage increased from 0 to 1 g L−1, the formation of Br-DBPs (e.g., TBM and DBCM) was significantly improved, while the formation of Cl-DBPs (e.g., TCM, TCAN and DCAN) reduced. Higher ZVI dosage exhibited inhibitory effect on Br-DBPs formation due to the competition between ZVI and free chlorine (HOCl/OCl−). The bromine substitution factor (BSF) of THMs significantly decreased from 0.61 ± 0.06 to 0.22 ± 0.02, as the pH was raised from 5.0 to 9.0. Besides, the increase of initial BrO3− concentration significantly improved the formation of Br-DBPs and decreased the formation of Cl-DBPs, leading to an obvious rise on the BSF of THMs. As the initial concentration of HOCl increased, all THMs and HANs gradually increased. Moreover, the analysis based on the cytotoxicity index (CTI) of the determined DBPs showed that reduction of BrO3− by ZVI during chlorination had certain risks in real water sources, which should be paid attention to in the application.

A novel polyoxometalate-encapsulating 3D polycatenated metal-organic framework

A novel polyoxometalate-encapsulating polycatenated metal-organic framework, (bib)0.5[Cu2(bib)3.5(GeW12O40)]·H2O (1) (bib = 1,4-bis(1-imidazol-yl)-2,5-dimethyl benzene), has been synthesized under hydrothermal conditions. In compound 1, 1D molecular ladders and 2D square grid layers is further catenated to the two adjacent such motifs in inclined fashion to give an 1D+2D→3D polycatenaned metal-organic framework with nanotube channels, in which nanosized Keggin anions as guests are encapsulated for the first time. Compound 1 represents a first case of Keggin-type polyoxometalate-encapsulating 1D+2D→3D polycatenated metal-organic framework. The electrochemical studies show that modified electrode of 1 exhibits highly efficient electrocatalytic activity toward reduction of inorganic molecule bromate (BrO3-). The electrocatalytic reaction mechanism of 1-GCE toward reduction of BrO3- has been illuminated. The photoluminescence property of 1 was also investigated.

Synthesis, structure and electrochemical properties of a FeIII–CeIII heterometallic sandwich-type tungstoantimonate with novel 2-D infinite structure [Ce(H2O)8][Ce(H2O)6][Fe4(H2O)10(B-β-SbW9O33)2]·16H2O

By the rational self-assembly of trivacant Keggin precursor [B-α-SbW9O33]9− with Fe3+ and Ce3+ cations in the conventional aqueous solution, a novel FeIII–CeIII heterometallic sandwich-type tungstoantimonate [Ce(H2O)8][Ce(H2O)6] [Fe4(H2O)10(B-β-SbW9O33)2]·16H2O (1) has been successfully synthesized and further structurally characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction. Structural analysis indicates that the 2-D infinite sheet of 1 consists of the Krebs' sandwich-type [Fe4(H2O)10(B-β-SbW9O33)2]6− subunits and Ce3+ linkers. 1 represents the rare purely inorganic FeIII–CeIII heterometallic tungstoantimonate derivative with the 2-D infinite sheet. The electrochemical and electrocatalytic properties of 1 have been systemically studied in 0.5mol·L−1 Na2SO4+H2SO4 supporting electrolyte, moreover, 1 exhibits the obvious electrocatalytic activity towards the reduction of BrO3− and NO2−.

Preparation, electrochemical properties and electrocatalytic activity of Zn-substituted tungstoborate modified electrode.

3-Aminopropyltrimethoxysilane (APTMS) was covalently grafted on a glassy carbon electrode (GCE) by silicon-oxygen bonds formation. The APTMS-modified GCE was used as a suitable charged substrate to fabricate Keggin Zn-substituted tungstoborate (BW11Zn)-consisting monolayer film through layer-by-layer assembly based on the electrostatic attraction. This modification strategy is proven to be a general one suitable for anchoring many kinds of POMs on the APTMS-modified GCE. The APTMS/BW11Zn film obtained on GCE is electrochemically active in acid aqueous solutions and exhibited three pairs of well defined, stable and quasi-reversible cyclic voltammetry peaks in the pH range 0-2. The anodic and cathodic peak currents are linearly proportional to the scan rate in the 200-1000 mV s(-1), indicating a surface confined electrode process. The formal potentials of BW11Zn film, E0 versus saturated calomel electrode (SCE), are -0.27, -0.43, -0.55 V in pH 1 H2SO4 solution and changed linearly with the slope of 44, 63, and 60 mV/pH in the pH range 0-2, respectively. The BW11Zn/APTMS/GC electrode shows good catalytic activity for the reduction of BrO3-, NO2- and H2O2.

ChemInform Abstract: Functionalized Polyoxometalates with Covalently Linked Bisphosphonate, N‐Donor or Carboxylate Ligands: From Electrocatalytic to Optical Properties

AbstractReview: Zn, Co, Ni, Mo, and W POMs; 133 refs.

碳纳米管/聚二烯丙基二甲基氯化铵/磷钼酸复合膜的组装及其在溴酸盐检测中的应用

Electrostatic layer-by-layer assembly technique was used to prepared a multiwalled carbon nanotubes(MWCNT)/poly(diallyldimethylammonium chloride) (PDDA) multilayer onto a glassy carbon electrode (GC). {PDDA/MWCNT} n -PMo12 composite films modified GC were constructed via cyclic voltammograms of phosphomolybdic acid (PMo12) onto {MWCNT/PDDA} n /GC. The microstructure of {MWCNT/PDDA} n and {PDDA/MWCNT} n -PMo12 were characterized by SEM. The electrochemical and electrocatalytic behaviors of GC/{MWCNT/PDDA} n -PMo12 modified electrode to BrO3- were discussed in this work. The sensor based on the GC/{MWCNT/PDDA} n -PMo12 electrode has excellent electrocatalytic activity to the reduction of BrO3-. Under the optimum conditions, the amperometric responses of BrO3- at GC/{MWCNT/PDDA} n -PMo12 electrode was investigated by i-t curve method. The results showed that the BrO3-sensor has a detection limit of 20 nM, a sensitivity of 13.81 mA mM-1 cm-2, a response time 1.53 s and a linear range from 50 nM to 400 nM.

The Electrochemical Properties of 12-Molybdophosphoric Acid Modified Ionic Liquid Carbon Paste Electrode

A [C8mim]3PMo12O40-modified ionic liquid carbon paste electrode ([C8mim]3PMo12O40-ILCPE, C8mim = 1-methyl-3-octylimidazolium) was successfully fabricated. Its electrochemical properties were carried out on the cyclic voltammograms. The results of the cyclic voltammograms indicated that [C8mim]3PMo12O40-ILCPE exhibited remarkable electrocatalytic activities toward the reduction of BrO3− and good stability. The value of Ipc was as a function with the concentration of bromate from 2 × 10−6 to 1 × 10−4 M, which indicated that the [C8mim]3PMo12O40-ILCPE can be a candidate for electrochemical sensor.

Electrochemical behavior of an inorganic–organic hybrid based on isopolymolybdate anions and ethylenediamine

The one-dimensional inorganic–organic compound, (C2H10N2)[Mo3O10], was synthesized hydrothermally, and characterized by single crystal X-ray diffraction. The compound was used as a bulk-modifier to fabricate a renewable three-dimensional chemically modified carbon paste electrode (Mo-CPE) by direct mixing. The electrochemical properties of (C2H10N2)[Mo3O10]-modified Mo-CPE were investigated with respect to their pH-dependence, stability and electrocatalytic activity. The hybrid material bulk modified Mo-CPE not only displays good electrocatalytic activity toward the reduction of BrO3−, IO3−, NO2− and H2O2, but also exhibits good stability and multiple repeatability by simply polishing on the surface of a wet filter paper, a feature which is important for practical applications.

Multilayer films of cationic surfactants incorporating polyoxometalate on electrodes

A new kind of multilayer of didodecyldime- thylammonium bromide (DDAB) and 1:12 phospho- molybdic anions (PMo12) was achieved on the surface of a wax-impregnated graphite (WIG) electrode by ion exchange and electrostatic interaction. The character- ization and electrochemical behavior of the multilayer films of DDAB/PMo12 is described in detail. The chemically modified electrode was shown to exhibit an excellent electrocatalytic activity toward the reduction of BrO3 - anion in 0.5 M H2SO4 and possesses several attractive features, such as simple preparation, fast response, good stability, etc.

Comparative studies on electrochemical behavior and electrocatalytic properties of heteropolyanion-containing multilayer films prepared by two methods

Two modification methods for multilayer formation, i.e. immersion growth and electrochemical growth, were studied comparatively for their influence on the electrochemical behavior and the electrocatalytic properties of the thus-fabricated SiMo11V-containing multilayer films. Electrochemical growth was proven to be a more suitable method than immersion growth in preparing uniform ultrathin multilayer self-assemblies with good functions. We investigated the effects of scan rate and pH on the electrochemical behavior of the monolayer and multilayer films. We also compared the electrocatalytic effects on the reduction of BrO3− and HNO2 by the multilayer films prepared by the two methods. Moreover, the influence of multilayer thickness and the identity of the outermost layer on the electrocatalytic properties were studied. Much higher catalytic currents appeared on the thicker multilayer films than those on the thinner ones. On the other hand, the catalytic currents became smaller when the multilayer films with SiMo11V as the outermost layer were covered with an additional quarternized poly(4-vinylpyridine) layer partially complexed with osmium bis(2,2′-bypyridine) chloride (QPVP–Os layer). These influences were believed to be due to the different quantities of electrocatalyst loaded in the multilayer films and the blocking effect of the QPVP–Os outermost layer.

Reduction of BrO-3 with Urea and Thiourea

Reduction of BrO-3 with Urea and Thiourea