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Uwe Heiko Bunz, Matthias Müller, Stella Beglaryan, Silke Koser, Sebastian Hahn, Olena Tverskoy, Frank Rominger
Herein we report the synthesis, spectroscopic and struc¬tural properties of novel 2,3-dicyano-substituted azaacenes containing three to six annelated rings as a fra¬me¬work. The targets were prepared by Pd-catalyzed coupling of diamino bis(tri-iso-propylsilylethynyl)benzene, naphthalene and -an¬thracene with either 4,5-dibromophthalonitrile or 6,7-dibromo-naphthalene-2,3-dicarbonitrile into the respective N,N'-dihydro-diazaacenes. Oxidation with MnO2 or PbO2 furnishes the dicyano-substituted diazaacenes in reasonable to good yields...
March 14, 2017: Chemistry: a European Journal
Yanyan Zhang, Qinglin Wang, Junkai Zhang, Xiaoxin Wu, Yanzhang Ma
We report the successful formation of an immutable array of α-PbO2 phase TiO2 nanotubes by compression of a TiO2 nanotube array in an anatase phase. During compression to 31.3 GPa, the TiO2 nanotubes started to directly transform from an anatase phase to a baddeleyite phase at 14.5 GPa and completed the transition at 30.1 GPa. Under decompression, the baddeleyite phase transformed to an α-PbO2 phase at 4.6 GPa, which was quenchable to ambient pressure. Notably the tubular array microstructure was retained after the application of ultra high pressure and undergoing a series of phase transformations...
April 7, 2017: Nanotechnology
Nam Tran, Patrick Drogui, Tuan Linh Doan, Thanh Son Le, Hoai Chau Nguyen
The presence of herbicide is a concern for both human and ecological health. Glyphosate is occasionally detected as water contaminants in agriculture areas where the herbicide is used extensively. The removal of glyphosate in synthetic solution using advanced oxidation process is a possible approach for remediation of contaminated waters. The ability of electrochemical oxidation for the degradation and mineralization of glyphosate herbicide was investigated using Ti/PbO2 anode. The current intensity, treatment time, initial concentration and pH of solution are the influent parameters on the degradation efficiency...
February 8, 2017: Environmental Technology
Gregory Gibson, Ziyun Wang, Christopher Hardacre, Wen-Feng Lin
The H2O splitting mechanism is a very attractive alternative used in electrochemistry for the formation of O3. The most efficient catalysts employed for this reaction at room temperature are SnO2-based, in particular the Ni/Sb-SnO2 catalyst. In order to investigate the H2O splitting mechanism density functional theory (DFT) was performed on a Ni/Sb-SnO2 surface with oxygen vacancies. By calculating different SnO2 facets, the (110) facet was deemed most stable, and further doped with Sb and Ni. On this surface, the H2O splitting mechanism was modelled paying particular attention to the final two steps, the formation of O2 and O3...
February 1, 2017: Physical Chemistry Chemical Physics: PCCP
Yury Minenkov, Valery V Sliznev, Luigi Cavallo
Accurate gas phase formation enthalpies, ΔHf, of metal oxides and halides are critical for the prediction of the stability of high temperature materials used in the aerospace and nuclear industries. Unfortunately, the experimental ΔHf values of these compounds in the most used databases, such as the NIST-JANAF database, are often reported with large inaccuracy, while some other ΔHf values clearly differ from the value predicted by CCSD(T) methods. To address this point, in this work we systematically predicted the ΔHf values of a series of these compounds having a group 4, 6, or 14 metal...
January 17, 2017: Inorganic Chemistry
Zesheng Xu, Han Liu, Junfeng Niu, Yijing Zhou, Chong Wang, Yue Wang
We prepared a hydroxyl multi-wall carbon nanotube-modified nanocrystalline PbO2 anode (MWCNTs-OH-PbO2) featuring high oxygen evolution potential, large effective area, and excellent electrocatalytic performance. The oxygen evolution potential and effective area of the MWCNTs-OH-PbO2 electrode were 1.5 and 3.7-fold higher than the traditional PbO2 electrode. Electrochemical degradation of pyridine in aqueous solution was investigated by using the MWCNTs-OH-PbO2 anode. Based on pyridine decay rate (93.8%), total organic carbon reduction (84...
December 29, 2016: Journal of Hazardous Materials
Zesheng Xu, Yanxin Yu, Han Liu, Junfeng Niu
Zr-doped nanocrystalline PbO2 (Zr-PbO2) film electrodes were prepared at different bath temperatures. The Zr-PbO2 electrode doped at 75°C (75-Zr-PbO2) featured high oxygen evolution overpotential, large effective area and good electrocatalytic performance. The oxygen evolution potential and the effective area of 75-Zr-PbO2 achieved 1.91V (vs. SCE) and 9.1cm(2), respectively. The removal efficiency and the defluorination ratio of PFOA reached 97.0% and 88.1% after 90min electrolysis. The primary mineralization products (i...
February 1, 2017: Science of the Total Environment
S López-Moreno, A H Romero, J Mejía-López, A Muñoz
In this work we report a complete structural and magnetic characterization of crystalline MnF2 under pressure obtained using first principle calculations. Density functional theory was used as the theoretical framework, within the generalized gradient approximation plus the Hubbard formalism (GGA+U) necessary to describe the strong correlations present in this material. The vibrational, the magnetic exchange couplings and the structural characterization of MnF2 in the rutile ground state structure and potential high pressure phases are reported...
December 7, 2016: Physical Chemistry Chemical Physics: PCCP
SeyedHosein Payandeh GharibDoust, Michael Heere, Magnus H Sørby, Morten B Ley, Dorthe B Ravnsbæk, Bjørn C Hauback, Radovan Černý, Torben R Jensen
Two new bimetallic sodium or potassium lanthanum borohydrides, NaLa(BH4)4 and K3La(BH4)6, are formed using La(BH4)3 free of metal halide by-products. NaLa(BH4)4 crystallizes in an orthorhombic crystal system with unit cell parameters, a = 6.7987(19), b = 17.311(5), c = 7.2653(19) Å and space group symmetry Pbcn. This compound has a new structure type built from brucite-like layers of octahedra (hcp packing of anions) with half of the octahedral sites empty leading to octahedral chains similar to rutile (straight chains) or α-PbO2 (zig-zag chains)...
November 17, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Nam Tran, Patrick Drogui, Satinder K Brar, Arnaud De Coninck
The synergistic effects were evaluated during the oxidation of carbamazepine using a sono-electrochemical process. The sono-electrochemical oxidation was performed using two types of experimental units (having 1L and 100L of working volume, respectively) and containing one anode (Ti/PbO2) and one cathode (Ti). Different operating parameters, including power of ultrasounds, current intensity and reaction time were investigated. The degree of synergy increased when the current intensity decreased, whereas it increased with the power of ultrasounds imposed...
January 2017: Ultrasonics Sonochemistry
Boutheina Gargouri, Olfa Dridi Gargouri, Ibtihel Khmakhem, Sonda Ammar, Ridha Abdelhèdi, Mohamed Bouaziz
Table olive processing wastewater (TOW) is a notoriously polluting due to its high organic and phenol content. To reduce them, an electrochemical process has been studied for the treatment of this effluent. Experiments were performed with a cell equipped with lead dioxide (PbO2) or boron-doped diamond (BDD) as anode and platinum as cathode, where Table Olive Wastewater (TOW) were destroyed by hydroxyl radicals formed at the anode surface from water oxidation. The comparative study of both systems shows the performance of the BDD anode compared to PbO2, explained by the large amounts of hydroxyl radicals generated effective at BDD anode and its synthesis characteristics...
January 2017: Chemosphere
Fengxian Ma, Yalong Jiao, Guoping Gao, Yuantong Gu, Ante Bilic, Stefano Sanvito, Aijun Du
By first-principle calculations, we have systematically studied the effect of strain/pressure on the electronic structure of rutile lead/stannic dioxide (PbO2/SnO2). We find that pressure/strain has a significant impact on the electronic structure of PbO2/SnO2. Not only can the band gap be substantially tuned by pressure/strain, but also a transition between a semiconductor and a gapless/band-inverted semimetal can be manipulated. Furthermore, the semimetallic state is robust under strain, indicating a bright perspective for electronics applications...
October 5, 2016: ACS Applied Materials & Interfaces
Chun-Wei Chiang, Ding-Quan Ng, Yi-Pin Lin, Pei-Jen Chen
Nanoscale lead dioxide (nPbO2(s)) is a corrosion product formed from the chlorination of lead-containing plumbing materials. This metal oxide nanoparticle (NP) plays a key role in determining lead pollution in drinking water and receiving water bodies. This study uses nPbO2(s) and medaka fish (Oryzias latipes) as surrogates to investigate the aqueous fate and toxicological risk of metal oxide NPs associated with water matrices. The larvae of medaka were treated with solutions containing nPbO2(s) or Pb(II)aq in different water matrices for 7-14 days to investigate the in vivo toxic effects of NPs...
October 4, 2016: Environmental Science & Technology
Lesley M Foley, Robert S B Clark, Alberto L Vazquez, T Kevin Hitchens, Henry Alexander, Chien Ho, Patrick M Kochanek, Mioara D Manole
BACKGROUND: Disturbances in cerebral blood flow (CBF) and brain oxygenation (PbO2) are present early after pediatric cardiac arrest (CA). CBF-targeted therapies improved neurological outcome in our CA model. To assess the therapeutic window for CBF- and PbO2-targeted therapies, we propose to determine if CBF and PbO2 disturbances persist at 24 h after experimental pediatric CA. METHODS: Regional CBF and PbO2 were measured at 24 h after asphyxial CA in immature rats (n = 26, 6-8/group) using arterial spin label MRI and tissue electrodes, respectively...
January 2017: Pediatric Research
Kallyni Irikura, Nerilso Bocchi, Romeu C Rocha-Filho, Sonia R Biaggio, Jesús Iniesta, Vicente Montiel
The statistical Response Surface Methodology (RSM) is applied to investigate the effect of different parameters (current density, j, NaCl concentration, [NaCl], pH, and temperature, θ) and their interactions on the electrochemical degradation of the Acid Green (AG) 28 dye using a Ti/β-PbO2 or Ti-Pt/β-PbO2 anode in a filter-press reactor. LC/MS is employed to identify intermediate compounds. For both anodes, the best experimental conditions are j = 50 mA cm(-2), [NaCl] = 1.5 g L(-1), pH = 5, and θ = 25 °C...
December 1, 2016: Journal of Environmental Management
Chong Wang, Yanxin Yu, Lifeng Yin, Junfeng Niu, Li-An Hou
Electrochemical degradation of ibuprofen (IBP) was performed on three types of Ti-based metal oxide electrodes. The degradation of IBP followed pseudo-first-order kinetics and the electrochemical degradation rate constant (k) over Ti/SnO2-Sb/Ce-PbO2 (9.4 × 10(-2) min(-1)) was 2.0 and 1.7 times of the values over Ti/Ce-PbO2 (4.7 × 10(-2) min(-1)) and Ti/SnO2-Sb (5.6 × 10(-2) min(-1)), respectively. The removal of total organic carbon and the energy consumption per order for IBP degradation were 93...
November 2016: Chemosphere
Atsuhiro Osuka, Daiki Shimizu, Seung-Kyu Lee, Dongho Kim
meso-Nitrosubporphyrinatoboron(III) was synthesized by nitration of meso-free subporphyrin with AgNO2/I2. Subsequent reduction with a combination of NaBH4 and Pd/C gave meso-aminosubporphyrinatoboron(III). meso-Nitro- and meso-amino-groups significantly influenced the electronic properties of subporphyrin, which has been confirmed by NMR and UV/vis spectra, electrochemical analysis, and DFT calculations. Oxidation of meso-aminosubporphyrinatoboron(III)s with PbO2 cleanly gave meso-to-meso azosubporphyrinatoboron(III)s that exhibited almost coplanar conformations and large electronic interaction through the azo-bridge...
August 16, 2016: Chemistry, An Asian Journal
Indu M Sasidharan Pillai, Ashok K Gupta
Application of a newly developed electrode material, PbO2 coated on mild steel plate (MS-PbO2), for the degradation of malachite green (MG) by photocatalytic oxidation (PCO), electrochemical oxidation (ECO) and photoelectrochemical oxidation (PEC) was explored. PEC performed marginally better at lower current density. However, the performances of PEC and ECO were equally good at higher current densities. One variable at a time optimization was carried out to identify the major parameters influencing ECO. Multivariate optimization was carried out with NaCl concentration, current density and pH as the variables and chemical oxygen demand (COD) removal efficiency and current efficiency (CE) as the responses...
November 9, 2016: Journal of Environmental Science and Health. Part A, Toxic/hazardous Substances & Environmental Engineering
Henrietta A Headlam, Peter A Lay
Evidence is growing that metabolites of Cr(III) dietary supplements are partially oxidized to carcinogenic Cr(VI) and Cr(V) in vivo. Hence, we examined oxidations of Cr(III) peptide (triglycine, tetraglycine and pentaglycine) complexes to Cr(VI) and Cr(V) by PbO2 at 37°C and physiological pH values between 3.85 and 7.4. The products were characterized by EPR and UV/Vis spectroscopies and electrospray mass spectrometry. At pH3.85, the monomeric Cr(V) complexes produced were relatively unstable and degraded over min to hr under the acidic conditions...
June 16, 2016: Journal of Inorganic Biochemistry
Carlos Eduardo O Andrade, André F Oliveira, Antônio A Neves, Maria Eliana L R Queiroz
EDTA is an important ligand used in many industrial products as well as in agriculture, where it is employed to assist in phytoextraction procedures and the absorption of nutrients by plants. Due to its intensive use and recalcitrance, it is now considered an emerging pollutant in water, so there is great interest in techniques suitable for its monitoring. This work proposes a method based on formation of the Mn(III)-EDTA complex after oxidation of the Mn(II)-EDTA complex by PbO2 immobilized on cyanoacrylate spheres...
November 5, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
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