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Yi Fan, Yiwen Li, Deyi Wu, Chunjie Li, Hainan Kong
A unique sediment-capping agent consisting of a zeolite/hydrous zirconia composite (ZHZ) was developed and tested for P-immobilization in the overlying water and sediment cores from a freshwater pond. In the ZHZ, NaP1 zeolite was covered with hydrous zirconia, which existed as an amorphous phase. Experimental results in pond water indicated that ZHZ could efficiently remove soluble reactive phosphorus. The 28-day sediment incubation experiments showed that capping sediment with ZHZ resulted in a more efficient, rapid and sustained decrease in P concentration when compared with the traditional alum treatment method...
June 12, 2017: Water Research
Yanyan Mu, Yu Zhang, Jiangyang Fan, Cuili Guo
SSZ-13 zeolite has been identified as effective material for catalysts and membranes for years because of its structure, but the long crystallization time is the main obstacle for the industry application. The sonochemical-assisted method was identified as one of the potential pre-treatment methods which could reduce the formation duration of zeolites as well as other microporous and mesoporous materials. In this work, zeolite SSZ-13 was prepared by ultrasound pretreatment prior to hydrothermal crystallization...
September 2017: Ultrasonics Sonochemistry
Agnieszka Magdziarz, Juan C Colmenares, Olga Chernyayeva, Dmytro Lisovytskiy, Justyna Grzonka, Krzysztof Kurzydłowski, Kinga Freindl, Józef Korecki
Fe(3+)/TiO2/zeolite Y photocatalyst synthesized by using sonophotodeposition method was compared with photocatalysts prepared by simple photodeposition and sonodeposition methods in order to clarify the role of light irradiation and ultrasounds while they are used simultaneously. To gain an insight into the mechanism of this method a detailed characterization of the photocatalysts was carried out by means of the following techniques: UV-vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, Mössbauer measurements and photocatalytic test reaction...
September 2017: Ultrasonics Sonochemistry
Damien McCarthy, Grant C Edwards, Mae S Gustin, Andrew Care, Matthieu B Miller, Anwar Sunna
Soils contaminated with mercury (Hg) have proved expensive and logistically difficult to remediate. Research continues into finding suitable environmentally-friendly and efficient ways of achieving this end. Bioremediation is an option, which employs the strategies microorganisms have evolved to deal with Hg. One microbial strategy involves uptake and intracellular volatilisation of mercuric ions, which passively diffuse from the cell and back into the atmosphere. In this work, Pseudomonas veronii cells grown to stationary phase were immobilised in a xanthan gum-based biopolymer via encapsulation...
June 14, 2017: Chemosphere
Pengwei Wang, Guofeng Zhao, Yu Wang, Yong Lu
Oxidative coupling of methane (OCM) is a promising method for the direct conversion of methane to ethene and ethane (C2 products). Among the catalysts reported previously, Mn2O3-Na2WO4/SiO2 showed the highest conversion and selectivity, but only at 800° to 900°C, which represents a substantial challenge for commercialization. We report a TiO2-doped Mn2O3-Na2WO4/SiO2 catalyst by using Ti-MWW zeolite as TiO2 dopant as well as SiO2 support, enabling OCM with 26% conversion and 76% C2-C3 selectivity at 720°C because of MnTiO3 formation...
June 2017: Science Advances
Zhenchao Zhao, Hui Shi, Chuan Wan, Mary Y Hu, Yuanshuai Liu, Donghai Mei, Donald M Camaioni, Jian Zhi Hu, Johannes A Lercher
The reaction mechanism of solid-acid-catalyzed phenol alkylation with cyclohexanol and cyclohexene in the apolar solvent decalin has been studied using in situ (13)C MAS NMR spectroscopy. Phenol alkylation with cyclohexanol sets in only after a majority of cyclohexanol is dehydrated to cyclohexene. As phenol and cyclohexanol show similar adsorption strength, this strict reaction sequence is not caused by the limited access of phenol to cyclohexanol, but is due to the absence of a reactive electrophile as long as a significant fraction of cyclohexanol is present...
June 19, 2017: Journal of the American Chemical Society
Yi Liu, Yujie Ban, Weishen Yang
In the past decade, a huge development in rational design, synthesis, and application of molecular sieve membranes, which typically included zeolites, metal-organic frameworks (MOFs), and graphene oxides, has been witnessed. Owing to high flexibility in both pore apertures and functionality, MOFs in the form of membranes have offered unprecedented opportunities for energy-efficient gas separations. Reports on the fabrication of well-intergrown MOF membranes first appeared in 2009. Since then there has been tremendous growth in this area along with an exponential increase of MOF-membrane-related publications...
June 19, 2017: Advanced Materials
Jie Liang, Zibin Liang, Ruqiang Zou, Yanli Zhao
Crystalline porous materials are important in the development of catalytic systems with high scientific and industrial impact. Zeolites, ordered mesoporous silica, and metal-organic frameworks (MOFs) are three types of porous materials that can be used as heterogeneous catalysts. This review focuses on a comparison of the catalytic activities of zeolites, mesoporous silica, and MOFs. In the first part of the review, the distinctive properties of these porous materials relevant to catalysis are discussed, and the corresponding catalytic reactions are highlighted...
June 19, 2017: Advanced Materials
Maarten Houlleberghs, Andreas Hoffmann, Dirk Dom, Christine E A Kirschhock, Francis Taulelle, Johan A Martens, Eric Breynaert
Zeolites are microporous materials driving industrial scale adsorption, ion exchange and catalytic processes. Their water content dramatically impacts their properties, but its quantification with Karl Fisher titration or thermal gravimetric analysis is problematic. Combining standard addition of water with 1H MAS NMR detection, absolute quantification of water in microporous materials becomes possible. The method was demonstrated on 5 different, commercially available zeolites.
June 19, 2017: Analytical Chemistry
Qingxue Lai, Junjie Zhu, Yingxuan Zhao, Yanyu Liang, Jianping He, Junhong Chen
A transition-metal-nitrogen/carbon (TM-N/C, TM = Fe, Co, Ni, etc.) system is a popular, nonprecious-metal oxygen reduction reaction (ORR) electrocatalyst for fuel cell and metal-air battery applications. However, there remains a lack of comprehensive understanding about the ORR electrocatalytic mechanism on these catalysts, especially the roles of different forms of metal species on electrocatalytic performance. Here, a novel CuN/C ORR electrocatalyst with a hybrid Cu coordination site is successfully fabricated with a simple but efficient metal-organic-framework-based, metal-doping-induced synthesis strategy...
June 19, 2017: Small
Mukesh Kumar Awasthi, Meijing Wang, Ashok Pandey, Hongyu Chen, Sanjeev Kumar Awasthi, Quan Wang, Xiuna Ren, Altaf Hussain Lahori, Dong-Sheng Li, Ronghua Li, Zengqiang Zhang
In the present study, biochar combined with a higher dosage of zeolite (Z) and biochar (B) alone were applied as additives for dewatered fresh sewage sludge (DFSS) composting using 130-L working volume lab-scale reactors. We first observed that the addition of a mixture of B and Z to DFSS equivalent to 12%B+10% (Z-1), 15% (Z-2) and 30% (Z-3) zeolite (dry weight basis) worked synergistically as an amendment and increased the composting efficiency compared with a treatment of 12%B alone amended and a control without any amendment...
June 13, 2017: Waste Management
Keith T Butler, Christopher H Hendon, Aron Walsh
Increasing numbers of electrically active porous framework materials are being reported, with conductivities that make them attractive for technological applications. As design strategies for efficient carrier transport emerge, the next challenge is to incorporate the materials into a functioning device. In thin-film devices interface effects are of critical importance to overall function. In this article we present a method to identify compatible materials combinations to achieve mechanically robust, electronically optimal pairings...
June 16, 2017: Faraday Discussions
Stefania Tanase-Grecea, Mascha Gehre, Zhiyong Guo, Gadi Rothenberg
Petrochemical refineries must separate hydrocarbons mixtures on a large scale for the production of fuels and chemicals. Most often, these hydrocarbons are separated by distillation, which is extremely energy-intensive. This high energy cost can be mitigated by developing materials that can enable efficient adsorptive separation. In this critical review, we first outline the principles of adsorptive separation. We then examine the case for C4 separations using zeolites and metal-organic frameworks (MOFs). By analysing both experimental and theoretical studies, we outline the challenges and opportunities in C4 separation, with a focus on the separation mechanisms and structure-selectivity correlations...
June 15, 2017: ChemSusChem
Sanket Sabnis, Vijesh A Tanna, Chao Li, Jiaxin Zhu, Vivek Vattipalli, Stephen S Nonnenmann, Guan Sheng, Zhiping Lai, H Henning Winter, Wei Fan
Layered zeolite precursors were successfully exfoliated by brief shearing or sonication with the assistance of commercially available telechelic liquid polybutadienes at room temperature. The exfoliated zeolite nanosheets can form a stable suspension in an organic solvent, providing exciting potential for the fabrication of zeolite membranes, composite materials and hierarchical zeolites.
June 16, 2017: Chemical Communications: Chem Comm
Hessam Malmir, Muhammad Sahimi, M Reza Rahimi Tabar
Polydisperse packings of cubic particles arise in several important problems. Examples include zeolite microcubes that represent catalytic materials, fluidization of such microcubes in catalytic reactors, fabrication of new classes of porous materials with precise control of their morphology, and several others. We present the results of detailed and extensive simulation and microstructural characterization of packings of nonoverlapping polydisperse cubic particles. The packings are generated via a modified random sequential-addition algorithm...
May 2017: Physical Review. E
T G Pálfy, M Gerodolle, R Gourdon, D Meyer, S Troesch, P Molle
The performance of a vertical flow constructed wetland for combined sewer overflow treatment (CSO CW) has been evaluated. The full-scale site has been monitored for 3 years for major pollutants and for two load events for a range of micropollutants (metals, metalloids and polycyclic aromatic hydrocarbons (PAHs)). Performance were predominantly high (97% for total suspended solids (TSS), 80% for chemical oxygen demand (COD), 72% for NH4-N), even if several loads were extremely voluminous, pushing the filter to its limits...
June 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Xiaochun Zhu, Maarten G Goesten, Arjan J J Koekkoek, Brahim Mezari, Nikolay Kosinov, Georgy Filonenko, Heiner Friedrich, Roderigh Rohling, Bartłomiej M Szyja, Jorge Gascon, Freek Kapteijn, Emiel J M Hensen
In applying a multi-scale spectroscopic and computational approach, we demonstrate that the synthesis of stacked zeolite silicalite-1 nanosheets, in the presence of a long-tail diquaternary ammonium salt surfactant, proceeds through a pre-organised phase in the condensed state. In situ small-angle X-ray scattering, coupled to paracrystalline theory, and backed by electron microscopy, shows that this phase establishes its meso-scale order within the first five hours of hydrothermal synthesis. Quasi in situ vibrational and solid-state NMR spectroscopy reveal that this meso-shaped architecture already contains some elementary zeolitic features...
October 1, 2016: Chemical Science
Matthew R Ryder, Thomas D Bennett, Chris S Kelley, Mark D Frogley, Gianfelice Cinque, Jin-Chong Tan
We present the first use of in situ far-infrared spectroscopy to analyze the thermal amorphization of a zeolitic imidazolate framework material. We explain the nature of vibrational motion changes during the amorphization process and reveal new insights into the effect that temperature has on the Zn-N tetrahedra.
June 14, 2017: Chemical Communications: Chem Comm
Alfonso Atitlán-Gil, Martín M Bretón-de la Loza, José C Jiménez-Ortega, Helen Belefant-Miller, Gabriel Betanzos-Cabrera
BACKGROUND: Activated and micronized zeolites are used as detoxifying agents in humans. Detoxification is attributed to their ability to reduce lipid peroxidation by scavenging free radicals. OBJECTIVE: To evaluate activated and micronized zeolites as modulators of cellular oxidative stress in Mexican smokers without lung diseases. METHODS: Randomized clinical trial. Subjects were randomly divided into three groups: activated and micronized zeolites, n = 29; vitamin E, an accepted antioxidant, n = 29; and maltodextrin as control, n = 27...
May 2017: Revista de Investigación Clínica; Organo del Hospital de Enfermedades de la Nutrición
M Rubeš, M Trachta, E Koudelková, R Bulánek, V Kasneryk, O Bludský
Physical adsorption of methane in purely siliceous molecular sieves prepared by a recently discovered synthetic pathway using 2D zeolites as nanoscale building blocks has been investigated by means of combined experimental and theoretical approaches. The DFT/CC-based method has been tested on ADOR zeolites of the UTL family and a few experimentally well-characterized siliceous zeolites. Excellent agreement between theoretical and experimental heats of adsorption has been found for OKO, PCR, MFI, CHA and AEI zeolites...
June 14, 2017: Physical Chemistry Chemical Physics: PCCP
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