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Zhen Tan, Pengwan Chen, Qiang Zhou, Jianjun Liu, Xiaofeng Mei, Bi Wang, Naifu Cui
The phase transformation behavior of anatase and rutile titanium dioxide with particle sizes of 60 nm and 150 nm under shock compression have been investigated. To increase the shock pressure and reduce the shock temperature, copper powder and a small amount of paraffin were mixed with the TiO2 powder. The shock recovered samples were characterized by X-ray diffraction, Raman spectroscopy, and transmission electron microscope. The results indicate that both anatase and rutile TiO2 can transform to α-PbO2 phase TiO2 through shock-induced phase transition...
May 22, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
A S Rodrigues, M J Nunes, A Lopes, J N Silva, L Ciríaco, M J Pacheco
The electrodegradation of the 4-aminonaphthalene-1-sulfonic acid (4AN1S), 5-aminonaphthalene-2-sulfonic acid (5AN2S) and 8-aminonaphthalene-2-sulfonic acid (8AN2S) was studied, using two electrode materials as anode, BDD and Ti/Pt/PbO2 , and two different electrolytes, sodium sulfate and sodium chloride. The highest COD removal rates were obtained at BDD: for 5AN2S and 8AN2S results were similar in both electrolytes; for 4AN1S, results were better in sodium chloride. The lowest COD removal rates were obtained at the system Ti/Pt/PbO2 -sodium sulfate, for all the studied amines...
April 18, 2018: Chemosphere
Xuan Xing, Jinren Ni, Xiuping Zhu, Yi Jiang, Jianxin Xia
Whereas electrochemical oxidation is noted for its ability to degrade bio-refractory organics, it has also been incorrectly criticized for excessive energy consumption. The present paper rectifies this misunderstanding by demonstrating that the energy actually consumed in the degradation process is much less than that wasted in the side reaction of oxygen evolution. To minimize the side reaction, the possible highest instantaneous current efficiency (PHICE) for electrochemical oxidation of phenol at Boron-doped Diamond (BDD), Ti/SnO2 -Sb/PbO2 (PbO2 ), and Ti/SnO2 -Sb (SnO2 ) anodes has been investigated systematically, and found to reach almost 100% at the BDD anode compared with 23% at the PbO2 anode and 9% at the SnO2 anode...
April 17, 2018: Chemosphere
Yijing Xia, Qizhou Dai
In this work, the electrochemical degradation of antibiotic levofloxacin (LFX) has been studied using a novel rare earth La, Y co-doped PbO2 electrode. The effect of applied current density, pH value and initial LFX concentration on the degradation performance were systematically evaluated. The results demonstrated that electrochemical oxidation of LFX over the La-Y-PbO2 electrode was highly effective and the reaction followed an apparent first-order kinetic model. Considering the degradation efficiency and energy efficiency, the relative optimal conditions are identified as current density 30 mA cm-2 , pH 3 and initial LFX concentration 800 mg L-1 ...
April 18, 2018: Chemosphere
Karima Barbari, Rachid Delimi, Zahia Benredjem, Samia Saaidia, Abdelhak Djemel, Toufik Chouchane, Nihal Oturan, Mehmet A Oturan
The degradation of the herbicide fenuron was investigated using a new porous bifunctional electrode where the electrooxidation takes place on one side and the photocatalysis on the other side. The characterization of the synthetized bifunctional electrode (PbO2 /SnO2 -Sb2 O3 /Ti//Ti/TiO2 ) was performed by scanning electron microscopy, energy dispersive X-ray spectrometry and X-ray diffraction analysis and showed that the anodic side (Ti/SnO2 -Sb2 O3 /PbO2 ) is covered with a tetragonal β-PbO2 film and that the photocatalytic side (Ti/TiO2 ) consists of an anatase phase of TiO2 ...
March 20, 2018: Chemosphere
Jiade Wang, Tian Zhang, Yu Mei, Bingjun Pan
Reverse osmosis concentrate (ROC) of printing and dyeing wastewater remains as a daunting environmental issue, which is characterized by high salinity, chemical oxygen demand (COD), chroma and low biodegradability. In this study electro-oxidation process (PbO2 /Ti electrode) coupled with oxidation-reduction potential (ORP) online monitor was applied to treat such a ROC effluent. The results show that with the increase of specific electrical charge (Qsp ), the removal efficiencies of COD, TN and chroma increased significantly at the incipience and then reached a gentle stage; the optimal total current efficiency (12...
June 2018: Chemosphere
Keisuke Fujimoto, Atsuhiro Osuka
PtII -catalyzed cyclization of β-to-β ethynylene-bridged meso-amino NiII porphyrin dimer 4 followed by oxidation with PbO2 afforded 1,5-naphthyridine-fused porphyrin dimer 5 in good yield. This dimer possesses a redox-active 1,4-diazabutadiene linkage that is interconvertible with its reduced 1,2-diaminoethene linkage upon treatments with NaBH4 or PbO2 . The dimer 5 exhibits an intense NIR absorption and a narrow HOMO-LUMO gap with a remarkably low reduction potential mainly due to effective bonding interactions in the LUMO through the 1,4-diazabutadiene linkage...
May 2, 2018: Chemistry: a European Journal
Xuelian Wu, Judy N Hart, Xiaoming Wen, Liang Wang, Yi Du, Shi Xue Dou, Yun Hau Ng, Rose Amal, Jason Scott
It has been reported that photogenerated electrons and holes can be directed toward specific crystal facets of a semiconductor particle, which is believed to arise from the differences in their surface electronic structures, suggesting that different facets can act as either photoreduction or photo-oxidation sites. This study examines the propensity for this effect to occur in faceted, plate-like bismuth molybdate (Bi2 MoO6 ), which is a useful photocatalyst for water oxidation. Photoexcited electrons and holes are shown to be spatially separated toward the {100} and {001}/{010} facets of Bi2 MoO6 , respectively, by facet-dependent photodeposition of noble metals (Pt, Au, and Ag) and metal oxides (PbO2 , MnO x , and CoO x )...
March 21, 2018: ACS Applied Materials & Interfaces
Asghar Mesbahi, Hosein Ghiasi
The shielding properties of ordinary concrete doped with some micro and nano scaled materials were studied in the current study. Narrow beam geometry was simulated using MCNPX Monte Carlo code and the mass attenuation coefficient of ordinary concrete doped with PbO2 , Fe2 O3 , WO3 and H4 B (Boronium) in both nano and micro scales was calculated for photon and neutron beams. Mono-energetic beams of neutrons (100-3000 keV) and photons (142-1250 keV) were used for calculations. The concrete doped with nano-sized particles showed higher neutron removal cross section (7%) and photon attenuation coefficient (8%) relative to micro-particles...
June 2018: Applied Radiation and Isotopes
Daiki Shimizu, Atsuhiro Osuka
A benzene-1,3,5-triaminyl radical fused with three ZnII -porphyrins was synthesized through a three-fold oxidative fusion reaction of 1,3,5-tris(ZnII -porphyrinylamino)benzene followed by oxidation with PbO2 as key steps. This triaminyl radical has been shown to possess a quartet ground state with a doublet-quartet energy gap of 3.1 kJ mol-1 by superconducting quantum interference device (SQUID) studies. Despite its high-spin nature, this triradical is remarkably stable, which allows its separation and recrystallization under ambient conditions...
March 26, 2018: Angewandte Chemie
Seok Hyeon Gwon, Jeong-Hwan Oh, Minseok Kim, Sooseok Choi, Kyu Hwan Oh, Jeong-Yun Sun
Soft shields are required to protect the human body during a radioactive accident. However, the modulus of most soft shields, such as HDPE and epoxy, is high, thereby making it difficult to process them in wearable forms like gloves and clothes. We synthesized a soft shield based on a hydrogel that is very compliant, stretchable, and biocompatible. The shields were fabricated by integrating γ-ray-shield particles into hydrogels with an interpenetrating network. The soft shields containing 3.33 M of PbO2 exhibited a high attenuation coefficient (0...
January 30, 2018: Scientific Reports
Kang Liu, Jiakuan Yang, Sha Liang, Huijie Hou, Ye Chen, Junxiong Wang, Bingchuan Liu, Keke Xiao, Jingping Hu, Jin Wang
Spent lead-acid battery recycling by using conventional technologies is usually accompanied by releases of lead-containing wastewater as well as emissions of sulfur oxides and lead particulates that may potentially cause secondary pollution. This study developed a vacuum chlorinating process for simultaneous sulfur fixation and high-purity lead chloride (PbCl2 ) recovery from spent lead paste by using calcium chloride (CaCl2 ) and silicon dioxide (SiO2 ) as reagents. The process train includes pretreatment, simultaneous PbCl2 production and sulfur fixation, and PbCl2 volatilization...
February 20, 2018: Environmental Science & Technology
Szymon Z Konieczka, Florian Schlüter, Christoph Sindorf, Christoph Kerpen, Eduard Bernhardt, Maik Finze
Eleven-vertex closo and nido boron clusters with one or two exo-cyano groups were obtained by a series of consecutive cage-opening and cage-closure reactions starting from K2 [closo-B11 H11 ] (K2 1). In the first step, K2 1 reacts with KCN in water at elevated temperatures to yield [7-NC-nido-B11 H12 ]2- (5 a). Oxidation of 5 a with PbO2 gives [NC-closo-B11 H10 ]2- (2). In analogous subsequent reactions, dianion 2 was converted with KCN regioselectively to [7,9-(NC)2 -nido-B11 H11 ]2- (6 a), which was further oxidized to [(NC)2 -closo-B11 H9 ]2- (3)...
March 7, 2018: Chemistry: a European Journal
Ismail Fidan, Dominique Luneau, Vefa Ahsen, Catherine Hirel
Phthalocyanine derivatives do not cease to gain attention due to their numerous properties and applications (e.g., sensor, PDT). This makes them a unique scaffold for the design of new material. In this context, we were interested to develop the synthesis of an imino nitroxide-substituted phthalocyanine by Ullman's procedure; a challenge due to the intrinsic low solubility of most phthalocyanine derivative in much solvents. To overcome this solubility problem, we designed a phthalocyanine with bulky neopentyl substituents in peripheral positions as counterpart to the imino nitroxide moieties...
December 14, 2017: Chemistry: a European Journal
Wei Liu, Xuebang Wu, Yunfeng Liang, Changsong Liu, Caetano R Miranda, Sandro Scandolo
High-pressure single-crystal X-ray diffraction method with precise control of hydrostatic conditions, typically with helium or neon as the pressure-transmitting medium, has significantly changed our view on what happens with low-density silica phases under pressure. Coesite is a prototype material for pressure-induced amorphization. However, it was found to transform into a high-pressure octahedral (HPO) phase, or coesite-II and coesite-III. Given that the pressure is believed to be hydrostatic in two recent experiments, the different transformation pathways are striking...
December 5, 2017: Proceedings of the National Academy of Sciences of the United States of America
Yapeng He, Xue Wang, Weimin Huang, Rongling Chen, Wenli Zhang, Hongdong Li, Haibo Lin
A hydrophobic networked PbO2 electrode was deposited on mesh titanium substrate and utilized for the electrochemical elimination towards paracetamol drug. Three dimensional growth mechanism of PbO2 layer provided more loading capacity of active materials and network structure greatly reduced the mass transfer for the electrochemical degradation. The active electrochemical surface area based on voltammetric charge quantity of networked PbO2 electrode is about 2.1 times for traditional PbO2 electrode while lower charge transfer resistance (6...
February 2018: Chemosphere
Chen Zhang, Yingfeng Xu, Ping Lu, Xiaohua Zhang, Fangfang Xu, Jianlin Shi
A significant overpotential necessary for the electrochemical oxygen evolution reaction (OER) is one of the most serious disadvantages in water electrolysis, which, on the contrary, gives the probability to electrochemically produce ozone alternative to the common corona discharge. To effectively suppress the competitive OER and improve gaseous ozone escaping, here we present a capillary effect-enabled electrolysis strategy by employing an unusual partial-submersed mode of anode composed of a β-PbO2 cuboids-loaded bulk porous Pb, and realize a much enhanced electrocatalytic gaseous ozone production in comparison to the cases of solid Pb counterpart and/or usual submersion operation...
November 22, 2017: Journal of the American Chemical Society
Xiaolei Kang, Wei Sun, Limei Cao, Ji Yang
A novel cryptomelane-Ir (cry-Ir) electrode is prepared for Ir to enter into the cryptomelane (named as cry-Mn) structure and used for aspirin degradation. This catalyst can efficiently reduce the Ir usage from 85 to 34%. Also, the onset potential of cry-Ir is about 1.40 V and the over potential is about 0.34 V at 10 mA cm-2 , indicating that cry-Ir has an excellent oxygen evolution reaction (OER) activity to produce oxidizing species and can decrease electrolytic voltage during the electro-oxidation process...
November 2017: Environmental Science and Pollution Research International
Xingtang Liang, Lizhen Zheng, Shirong Li, Xiaoyu Fan, Shukun Shen, Daodao Hu
Constructing methods for cleaning stains on paper artworks that meet the requirements of preservation of cultural relics are still challenging. In response to this problem, a novel electrochemical cleaning method and the preparation of corresponding electrodes were proposed. For this purpose, the conductive graphene (rGO)/polyacryamide (PAM)/montmorillonite (MMT) composite hydrogel as cathode and PbO2-based material as anode were prepared and characterized. The electrochemical cleaning efficiencies of real sample and mimicking paper artifacts were evaluated, and the effects of the electrochemical cleaning on paper itself were detected...
August 18, 2017: Scientific Reports
Joseph P Smith, Frank C Smith, Joshua Ottaway, Alexandra E Krull-Davatzes, Bruce M Simonson, Billy P Glass, Karl S Booksh
The high-pressure, α-PbO2 -structured polymorph of titanium dioxide (TiO2 -II) was recently identified in micrometer-sized grains recovered from four Neoarchean spherule layers deposited between ∼2.65 and ∼2.54 billion years ago. Several lines of evidence support the interpretation that these layers represent distal impact ejecta layers. The presence of shock-induced TiO2 -II provides physical evidence to further support an impact origin for these spherule layers. Detailed characterization of the distribution of TiO2 -II in these grains may be useful for correlating the layers, estimating the paleodistances of the layers from their source craters, and providing insight into the formation of the TiO2 -II...
August 2017: Applied Spectroscopy
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