scholarly journals Gravimetric adsorption measurements of helium on natural clinoptilolite and synthetic molecular sieves at pressures up to 3500 kPa

2017 ◽  
Vol 244 ◽  
pp. 218-225 ◽  
Author(s):  
Arash Arami-Niya ◽  
Thomas E. Rufford ◽  
Greg Birkett ◽  
Zhonghua Zhu
Keyword(s):  
Molecular Sieves ◽  
Gravimetric Adsorption ◽  
Natural Clinoptilolite

scholarly journals Adsorption and Separation of the H2O/H2SO4 and H2O/C2H5OH Mixtures: A Simulated and Experimental Study

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 290
Author(s):  
Jesse Y. Rumbo Morales ◽  
Alan F. Perez Vidal ◽  
Gerardo Ortiz Torres ◽  
Alexis U. Salas Villalobo ◽  
Felipe de J. Sorcia Vázquez ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Molecular Sieves ◽  
Adsorption Process ◽  
Maximum Adsorption Capacity ◽  
Feed Composition ◽  
Azeotropic Point ◽  
Zeolite Type ◽  
Adsorption Processes ◽  
Pressure Swing ◽  
Natural Clinoptilolite

Adsorption processes are characterized by their kinetics and equilibrium isotherms described by mathematical models. Nowadays, adsorption with molecular sieves is a method used to separate certain elements or molecules from a mixture and produce hydrogen, nitrogen, oxygen, ethanol, or water treatment. This study had two main objectives. The first one was focused on the use of different natural (Clinoptilolite-S.L. Potosi, Clinoptilolite-Puebla, and Heulandite-Sonora) and synthetic (Zeolite Type 3A) adsorbents to separate the mixtures H 2 O / H 2 S O 4 and H 2 O / C 2 H 5 O H . It was determined that both Zeolite Type-3A and Heulandite-Sonora have greater adsorption capacity in a shorter time compared with the Clinoptilolites at different temperatures. The second objective was the simulation of a pressure swing adsorption process to dehydrate ethanol using the parameters obtained from Zeolite Type 3A (with maximum adsorption capacity). Several configurations were considered to calculate the appropriate nominal values for the optimal process. The results illustrate that the purity of ethanol is increased when the following parameters are considered in the adsorption process: a high pressure, a constant temperature between 100 and 120 ° C, a feed composition near the azeotropic point with lower water content, and a purge pressure near the vacuum. Finally, the results show that it is possible to take advantage of the length of the absorber bed in order to reduce the energy costs by increasing the ethanol production as well as complying with the international purity standards.

In vitro assembly of 2-D crystals from partially purified EA1 protein secreted by Bacillus anthracis strain Delta Sterne-1

1994 ◽  
Vol 52 ◽  
pp. 276-277
Author(s):  
Mary Beth Downs ◽  
Wilson Ribot ◽  
Joseph W. Farchaus
Keyword(s):  
Cell Wall ◽  
Molecular Sieves ◽  
Cell Envelope ◽  
Single Species ◽  
Supporting Cell ◽  
Surface Layers ◽  
Rabbit Igg ◽  
In Vitro Assembly ◽  
Covalently Linked

Many bacteria possess surface layers (S-layers) that consist of a two-dimensional protein lattice external to the cell envelope. These S-layer arrays are usually composed of a single species of protein or glycoprotein and are not covalently linked to the underlying cell wall. When removed from the cell, S-layer proteins often reassemble into a lattice identical to that found on the cell, even without supporting cell wall fragments. S-layers exist at the interface between the cell and its environment and probably serve as molecular sieves that exclude destructive macromolecules while allowing passage of small nutrients and secreted proteins. Some S-layers are refractory to ingestion by macrophages and, generally, bacteria are more virulent when S-layers are present.When grown in rich medium under aerobic conditions, B. anthracis strain Delta Sterne-1 secretes large amounts of a proteinaceous extractable antigen 1 (EA1) into the growth medium. Immunocytochemistry with rabbit polyclonal anti-EAl antibody made against the secreted protein and gold-conjugated goat anti-rabbit IgG showed that EAI was localized at the cell surface (fig 1), which suggests its role as an S-layer protein.

Rapid, Non-Toxic Synthesis of Beta Zeolites

2018 ◽  
Author(s):  
Felix Hemmann ◽  
Jonathan Hackebeil ◽  
Andreas Lißner ◽  
Florian Mertens
Keyword(s):  
Hydrofluoric Acid ◽  
Molecular Sieves ◽  
Toxic Chemicals ◽  
Lewis Acidity ◽  
Beta Zeolite ◽  
Seeded Growth ◽  
Related Research ◽  
Beta Zeolites ◽  
Growth Method ◽  
Fast Synthesis

Molecular sieves with beta zeolite topology are promising catalysts for various reactions as they exhibits extraordinary Lewis acidity. However, their industrial application and related research in academica is hindered because their synthesis is time consuming and typically involves toxic chemicals as hydrofluoric acid. Therefore, tetraethylammonium fluorid was tested as a non-toxic fluotide source for the synthesis of beta zeolites. In combination with the previously reported nano-seeded growth method, a fast synthesis of beta zeolites only involving non-toxic chemicals was possible. Synthesized zeolites show comparable selectivity in the Bayer-Villinger oxidation as conventional zeolites synthesized with hydrofluoric acid.<br>

CHARACTERISATION OF ETS-10 AND ET(Fe)S-10 MOLECULAR SIEVES EXCHANGED WITH DIFFERENT CATIONS

2004 ◽  
Vol 3 (3) ◽  
pp. 231-238
Author(s):  
Pierantonio De Luca ◽  
Lucia Catanzaro ◽  
Danilo Vuono ◽  
Janos B. Nagy ◽  
Alfonso Nastro
Keyword(s):  
Molecular Sieves

Mesoporous Silica Molecular Sieve based Nanocarriers: Transpiring Drug Dissolution Research

2017 ◽  
Vol 23 (3) ◽  
pp. 467-480 ◽  
Author(s):  
Satyanarayan Pattnaik ◽  
Kamla Pathak
Keyword(s):  
Drug Release ◽  
Mesoporous Silica ◽  
Molecular Sieves ◽  
Release Kinetics ◽  
Drug Loading ◽  
Scale Up ◽  
Water Soluble ◽  
Drug Dissolution ◽  
Water Soluble Drugs ◽  
Loading Methods

Background: Improvement of oral bioavailability through enhancement of dissolution for poorly soluble drugs has been a very promising approach. Recently, mesoporous silica based molecular sieves have demonstrated excellent properties to enhance the dissolution velocity of poorly water-soluble drugs. Description: Current research in this area is focused on investigating the factors influencing the drug release from these carriers, the kinetics of drug release and manufacturing approaches to scale-up production for commercial manufacture. Conclusion: This comprehensive review provides an overview of different methods adopted for synthesis of mesoporous materials, influence of processing factors on properties of these materials and drug loading methods. The drug release kinetics from mesoporous silica systems, the manufacturability and stability of these formulations are reviewed. Finally, the safety and biocompatibility issues related to these silica based materials are discussed.

The Effect of Acidity of Al and Fe Silicates with MFI Structure on Benzene and Toluene Alkylation with Isopropyl Alcohol

1996 ◽  
Vol 61 (8) ◽  
pp. 1115-1130 ◽  
Author(s):  
Jiří Čejka ◽  
Naděžda Žilková ◽  
Blanka Wichterlová
Keyword(s):  
Kinetic Study ◽  
Molecular Sieves ◽  
Isopropyl Alcohol ◽  
Acid Sites ◽  
Transport Rate ◽  
Reaction Products ◽  
Oh Groups ◽  
Benzene Alkylation ◽  
Toluene Alkylation ◽  
Low Strength

Kinetic study of toluene and benzene alkylation with isopropyl alcohol on alumo- and ferrisilicates of MFI structure has shown that the alkylation activity does not follow the acidity (both the number and strength of bridging OH groups) of these molecular sieves. The rate of the overall reaction is controlled by the desorption/transport rate of bulky, strongly adsorbed cymenes and cumene. A higher concentration of n-propyltoluenes compared to n-propylbenzene, both undesired reaction products, formed via a bimolecular isomerization of isopropyl aromate with benzene or toluene, was due to the higher reactivity of isopropyltoluene with toluene in comparison with that of cumene with benzene. It is concluded that ferrisilicates of MFI structure possessing low strength acid sites appear to be promising catalysts for achieving both a high isopropyl- and para-selectivity in toluene alkylation to p-cymene.

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