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https://www.readbyqxmd.com/read/30180540/impact-of-solution-chemistry-and-particle-anisotropy-on-the-collective-dynamics-of-oriented-aggregation
#1
Elias Nakouzi, Jennifer A Soltis, Benjamin A Legg, Gregory K Schenter, Xin Zhang, Trent R Graham, Kevin M Rosso, Lawrence M Anovitz, James J De Yoreo, Jaehun Chun
Although oriented aggregation of particles is a widely recognized mechanism of crystal growth, the impact of many fundamental parameters, such as crystallographically distinct interfacial structures, solution composition, and nanoparticle morphology, on the governing mechanisms and assembly kinetics are largely unexplored. Thus, the collective dynamics of systems exhibiting OA has not been predicted. In this context, we investigated the structure and dynamics of boehmite aggregation as a function of solution pH and ionic strength...
September 19, 2018: ACS Nano
https://www.readbyqxmd.com/read/30007383/electronic-response-of-aluminum-bearing-minerals
#2
Micah P Prange, Xin Zhang, Eugene S Ilton, Libor Kovarik, Mark H Engelhard, Sebastien N Kerisit
Aluminum-bearing minerals show different hydrogen evolution and dissolution properties when subjected to radiation, but the complicated sequence of events following interaction with high-energy radiation is not understood. To gain insight into the possible mechanisms of hydrogen production in nanoparticulate minerals, we study the electronic response and determine the bandgap energies of three common aluminum-bearing minerals with varying hydrogen content: gibbsite (Al(OH)3 ), boehmite (AlOOH), and alumina (Al2 O3 ) using electron energy loss spectroscopy, X-ray photoelectron spectroscopy, and first-principles electronic structure calculations employing hybrid density functionals...
July 14, 2018: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29873355/pressure-induced-stacking-disorder-in-boehmite
#3
Y Ishii, K Komatsu, S Nakano, S Machida, T Hattori, A Sano-Furukawa, H Kagi
The structure of an aluminum layered hydroxide, boehmite (γ-AlOOH), as a function of pressure was studied by using in situ synchrotron X-ray and neutron diffraction. Peak broadening, which is only found for hkl (h ≠ 0) peaks in the X-ray diffraction patterns, is explained by stacking disorder accompanying a continuously increasing displacement of the AlO6 octahedral layer along the a-axis. This finding could be the first experimental result for pressure-induced stacking disorder driven by continuous layer displacement...
June 20, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29801836/chitosan-reinforced-boehmite-nanocomposite-desiccant-a-promising-alternative-to-silica-gel
#4
Manju Rajamani, Shihabudheen M Maliyekkal
This paper describes the synthesis and performance evaluation of a granular solid desiccant composite synthesized through a sol-gel process at atmospheric pressure and ambient temperature. The composite desiccant essentially comprises of a biopolymer template, chitosan, and nanoscale boehmite particles embedded on the fibrils of the biopolymer. The chitosan fibers not only help in the formation of boehmite nanoparticles but also act as a reinforcing agent and enable the formation of sand like granules upon aging and drying...
August 15, 2018: Carbohydrate Polymers
https://www.readbyqxmd.com/read/29772834/mechanism-of-reduced-sintering-temperature-of-al%C3%A2-o%C3%A2-%C3%A2-zro%C3%A2-nanocomposites-obtained-by-microwave-hydrothermal-synthesis
#5
Iwona Koltsov, Julita Smalc-Koziorowska, Marta Prześniak-Welenc, Maria Małysa, Giora Kimmel, Jessica McGlynn, Alexey Ganin, Swietlana Stelmakh
A novel method to obtain Al₂O₃⁻ZrO₂ nanocomposites is presented. It consists of the co-precipitation step of boehmite (AlO(OH)) and ZrO₂, followed by microwave hydrothermal treatment at 270 °C and 60 MPa, and by calcination at 600 °C. Using this method, we obtained two nanocomposites: Al₂O₃⁻20 wt % ZrO₂ and Al₂O₃⁻40 wt % ZrO₂. Nanocomposites were characterized by Fourier transformed infrared spectroscopy, Raman spectroscopy, X-ray diffraction, and transmission electron microscopy...
May 17, 2018: Materials
https://www.readbyqxmd.com/read/29747433/efficient-manipulation-of-continuous-afi-type-aluminophosphate-membranes-with-distinctive-microstructures-on-macroporous-%C3%AE-al%C3%A2-o%C3%A2-substrates
#6
Luwei Geng, Hongfeng Dong, Xiufeng Liu, Baoquan Zhang
The availability of continuous and well-defined AFI-type aluminophosphate membranes (AFI membranes) would trigger their applications in innovative materials. A well-designed manipulation strategy is proposed to produce continuous AFI membranes with four different microstructures over porous α-Al₂O₃ substrates. A double-layer and highly c -oriented AFI membrane of hexagonal prisms is obtained when a thin layer of medium molecular weight (MMW) chitosan is employed as the structure-directing matrix together with aluminum isopropoxide (AIP) as the Al source...
May 9, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29742070/synthesis-of-transparent-dispersions-of-aluminium-hydroxide-nanoparticles
#7
Bo Chen, Jie-Xin Wang, Dan Wang, Xiao-Fei Zeng, Stuart M Clarke, Jian-Feng Chen
Transparent dispersions of inorganic nanoparticles are attractive materials in many fields. However, a facile method for preparing such dispersions of aluminium hydroxide nanoparticles is yet to be realized. Here, we report a direct reactive method to prepare transparent dispersions of pseudo-boehmite nanoparticles (1 wt%) without any surface modification, and with an average particle size of 80 nm in length and 10 nm in width, as well as excellent optical transparency over 94% in the visible range. Furthermore, transparent dispersions of boehmite nanoparticles (1...
July 27, 2018: Nanotechnology
https://www.readbyqxmd.com/read/29674746/gold-nanof%C3%A3-ve-surface-enhanced-raman-spectroscopy-visualizes-hypotaurine-as-a-robust-anti-oxidant-consumed-in-cancer-survival
#8
Megumi Shiota, Masayuki Naya, Takehiro Yamamoto, Takako Hishiki, Takeharu Tani, Hiroyuki Takahashi, Akiko Kubo, Daisuke Koike, Mai Itoh, Mitsuyo Ohmura, Yasuaki Kabe, Yuki Sugiura, Nobuyoshi Hiraoka, Takayuki Morikawa, Keiyo Takubo, Kentaro Suina, Hideaki Nagashima, Oltea Sampetrean, Osamu Nagano, Hideyuki Saya, Shogo Yamazoe, Hiroyuki Watanabe, Makoto Suematsu
Gold deposition with diagonal angle towards boehmite-based nanostructure creates random arrays of horse-bean-shaped nanostructures named gold-nanofève (GNF). GNF generates many electromagnetic hotspots as surface-enhanced Raman spectroscopy (SERS) excitation sources, and enables large-area visualization of molecular vibration fingerprints of metabolites in human cancer xenografts in livers of immunodeficient mice with sufficient sensitivity and uniformity. Differential screening of GNF-SERS signals in tumours and those in parenchyma demarcated tumour boundaries in liver tissues...
April 19, 2018: Nature Communications
https://www.readbyqxmd.com/read/29594279/enhancement-of-sod-activity-in-boehmite-supported-nanoreceptors
#9
Álvaro Martínez-Camarena, Estefanía Delgado-Pinar, Concepción Soriano, Javier Alarcón, José M Llinares, Roberto Tejero, Enrique García-España
The binuclear Cu2+ complex of a pyridinophane polyamine ligand ranking amongst the fastest SOD mimetics so far reported displays a remarkable SOD activity enhancement when grafted to the surface of boehmite (γ-AlO(OH)) nanoparticles (BNPs).
April 12, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29593253/development-characterization-and-dissolution-behavior-of-calcium-aluminoborate-glass-wasteforms-to-immobilize-rare-earth-oxides
#10
Miae Kim, Claire L Corkhill, Neil C Hyatt, Jong Heo
Calcium-aluminoborate (CAB) glasses were developed to sequester new waste compositions made of several rare-earth oxides generated from the pyrochemical reprocessing of spent nuclear fuel. Several important wasteform properties such as waste loading, processability and chemical durability were evaluated. The maximum waste loading of the CAB compositions was determined to be ~56.8 wt%. Viscosity and the electrical conductivity of the CAB melt at 1300 °C were 7.817 Pa·s and 0.4603 S/cm, respectively, which satisfies the conditions for commercial cold-crucible induction melting (CCIM) process...
March 28, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29548381/formation-of-coal-layered-double-hydroxide-on-the-boehmite-surface-and-its-role-in-tungstate-sorption
#11
Hyuck Hur, Richard J Reeder
Sorption of tungstate on boehmite (γ-AlOOH) is increased by co-sorption with Co2+ over the near-neutral pH range. Batch uptake experiments show up to a 3-fold increase in tungstate uptake over the range WO4 2- =50-1000μmol/L compared to boehmite not treated with Co2+ . Desorption experiments reveal a corresponding decrease in sorption reversibility for tungstate co-sorbed with Co2+ . Reaction of boehmite with Co2+ results in the formation of CoAl layered double hydroxide (LDH), as confirmed by X-ray diffraction and X-ray absorption spectroscopy...
March 2018: Journal of Environmental Sciences (China)
https://www.readbyqxmd.com/read/29525501/the-isotopic-exchangeability-of-phosphate-in-mg-al-layered-double-hydroxides
#12
Maarten Everaert, Kris Slenders, Kris Dox, Simon Smolders, Dirk De Vos, Erik Smolders
Layered double hydroxides (LDH) of Mg/Al are anion exchangers that are candidate materials for phosphate (PO4 ) recovery and recycling from waste streams. However, PO4 recycling in agriculture might be limited by incomplete desorption of PO4 from the minerals. This study was set up to identify the factors explaining irreversible PO4 sorption ("fixation") on LDHs by comparing the isotopic exchangeability (33 PO4 ) with the PO4 desorption from LDH materials and from boehmite as a P fixing reference mineral...
June 15, 2018: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/29514000/enhanced-hydrothermal-stability-of-%C3%AE-al-2-o-3-catalyst-supports-with-alkyl-phosphonate-coatings
#13
Tim Van Cleve, Devon Underhill, Mariana Veiga Rodrigues, Carsten Sievers, J Will Medlin
In this study, monolayers formed from organophosphonic acids were employed to stabilize porous γ-Al2 O3 , both as a single component and as a support for Pt nanoparticle catalysts, during exposure to hydrothermal conditions. To provide a baseline, structural changes of uncoated γ-Al2 O3 catalysts under model aqueous phase reforming conditions (liquid water at 200 °C and autogenic pressure) were examined over the course of 20 h. These changes were characterized by X-ray diffraction, NMR spectroscopy, N2 physisorption, and IR spectroscopy...
March 27, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29442773/boehmite-an-efficient-and-recyclable-acid-base-bifunctional-catalyst-for-aldol-condensation-reaction
#14
P C Rajan Reshma, Sekar Vikneshvaran, Sivan Velmathi
In this work boehmite was used as an acid-base bifunctional catalyst for aldol condensation reactions of aromatic aldehydes and ketones. The catalyst was prepared by simple sol-gel method using Al(NO3)3·9H2O and NH4OH as precursors. The catalyst has been characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), UV-visible spectroscopy (DRS), BET surface area analyses. Boehmite is successfully applied as catalyst for the condensation reaction between 4-nitrobenzaldehyde and acetone as a model substrate giving α, β-unsaturated ketones without any side product...
June 1, 2018: Journal of Nanoscience and Nanotechnology
https://www.readbyqxmd.com/read/29215277/review-of-the-scientific-understanding-of-radioactive-waste-at-the-u-s-doe-hanford-site
#15
Reid A Peterson, Edgar C Buck, Jaehun Chun, Richard C Daniel, Daniel L Herting, Eugene S Ilton, Gregg J Lumetta, Sue B Clark
This Critical Review reviews the origin and chemical and rheological complexity of radioactive waste at the U.S. Department of Energy Hanford Site. The waste, stored in underground tanks, was generated via three distinct processes over decades of plutonium extraction operations. Although close records were kept of original waste disposition, tank-to-tank transfers and conditions that impede equilibrium complicate our understanding of the chemistry, phase composition, and rheology of the waste. Tank waste slurries comprise particles and aggregates from nano to micro scales, with varying densities, morphologies, heterogeneous compositions, and complicated responses to flow regimes and process conditions...
January 16, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29190583/synthesis-of-cucl-boehmite-adsorbents-that-exhibit-high-co-selectivity-in-co-co-2-separation
#16
Kanghee Cho, Jungsu Kim, Hee Tae Beum, Taesung Jung, Sang Sup Han
We developed nanoporous adsorbent exhibiting unprecedented performance in separation of toxic carbon monoxide (CO). The adsorbent was prepared by dispersing CuCl on mesoporous boehmite via thermal monolayer dispersion route. A key point of the present synthesis is dispersing optimized amount of CuCl on the boehmite at a moderate temperature to maintain the characteristics of the boehmite. We performed a systematic study to reveal that a CuCl/boehmite composite (30wt% CuCl in total) thermally treated at 573K was the best optimized sample for CO separation...
February 15, 2018: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/29189734/fabrication-and-characterization-of-porous-mgal%C3%A2-o%C3%A2-ceramics-via-a-novel-aqueous-gel-casting-process
#17
Lei Yuan, Zongquan Liu, Zhenli Liu, Xiao He, Beiyue Ma, Qiang Zhu, Jingkun Yu
A novel and aqueous gel-casting process has been successfully developed to fabricate porous MgAl₂O₄ ceramics by using hydratable alumina and MgO powders as raw materials and deionized water as hydration agent. The effects of different amounts of deionized water on the hydration properties, apparent porosity, bulk density, microstructure, pore size distribution and compressive strength of the samples were investigated. The results indicated that the porosity and the microstructure of porous MgAl₂O₄ ceramics were governed by the amounts of deionized water added...
November 30, 2017: Materials
https://www.readbyqxmd.com/read/29038454/importance-of-interlayer-h-bonding-structure-to-the-stability-of-layered-minerals
#18
Michele Conroy, Jennifer A Soltis, Rick S Wittman, Frances N Smith, Sayandev Chatterjee, Xin Zhang, Eugene S Ilton, Edgar C Buck
Layered (oxy) hydroxide minerals often possess out-of-plane hydrogen atoms that form hydrogen bonding networks which stabilize the layered structure. However, less is known about how the ordering of these bonds affects the structural stability and solubility of these minerals. Here, we report a new strategy that uses the focused electron beam to probe the effect of differences in hydrogen bonding networks on mineral solubility. In this regard, the dissolution behavior of boehmite (γ-AlOOH) and gibbsite (γ-Al(OH)3) were compared and contrasted in real time via liquid cell electron microscopy...
October 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28994772/in-situ-characterization-of-boehmite-particles-in-water-using-liquid-sem
#19
Juan Yao, Bruce W Arey, Li Yang, Fei Zhang, Rachel Komorek, Jaehun Chun, Xiao-Ying Yu
In situ imaging and elemental analysis of boehmite (AlOOH) particles in water is realized using the System for Analysis at the Liquid Vacuum Interface (SALVI) and Scanning Electron Microscopy (SEM). This paper describes the method and key steps in integrating the vacuum compatible SAVLI to SEM and obtaining secondary electron (SE) images of particles in liquid in high vacuum. Energy dispersive x-ray spectroscopy (EDX) is used to obtain elemental analysis of particles in liquid and control samples including deionized (DI) water only and an empty channel as well...
September 27, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28972601/hydrogenous-spinel-%C3%AE-alumina-structure
#20
Jinshi Dong, Jun Wang, Lu Shi, Jiaqiang Yang, Jianqiang Wang, Bin Shan, Meiqing Shen
The structure of γ-Al2 O3 is still under debate. Here we report a H spinel structure evolved from pseudo-boehmite. A unit cell with two octahedral cationic vacancies and one bulk H was preferential in terms of calculated Gibbs energy, which was well consistent with experimental data. Bulk H was found to migrate out with elevated temperatures. Through calculating the migration barriers of every step, we observed that the "hopping" step was rate-determining. The hopping rates were further estimated by assuming a Boltzmann distribution of energies, and as a result they increased by 2 to 3 orders of magnitude from 500 °C to 800 °C...
October 18, 2017: Physical Chemistry Chemical Physics: PCCP
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