scholarly journals Dynamic molecular pockets on diffusion channel for efficient production of polymer-grade propylene

2021 ◽  
Author(s):  
Dan Li ◽  
Heng Zeng ◽  
Ting Wang ◽  
Mo Xie ◽  
Rong-Jia Wei ◽  
...  
Keyword(s):  
Single Crystal ◽  
Efficient Production ◽  
Separation Mechanism ◽  
Desorption Kinetics ◽  
Diffusion Channel ◽  
Complete Exclusion ◽  
Breakthrough Experiments ◽  
Adsorption Desorption ◽  
Molecular Sieving ◽  
Desorption Cycle

Abstract Size-based molecular sieving works well for rigid molecules with complete exclusion of larger ones, yet interaction-induced molecular sieving may offer unusual separation capability for molecules with matching physicochemical properties. Here we report a MOF material (XXU-3) featuring one-dimension channels with embedded molecular pockets opening to C3H6 and C3H8 at substantially different pressures. The dynamic nature of the pockets is revealed by single-crystal-to-single-crystal transformation upon exposure of the activated XXU-3 to C3H6 or C3H8 atmosphere. Breakthrough experiments demonstrate that XXU-3 is not only capable of separating C3H6 from C3H8 with record-high C3H6 productivity, but also the first MOF material realizing polymer-grade C3H6 production in a single adsorption-desorption cycle from an equimolar C3H6/C3H8 mixture. The underlying separation mechanism, namely orthogonal-array dynamic molecular sieving, is an exemplary strategy for both large separation capacity and fast adsorption-desorption kinetics. This work presents an ideal design for next-generation sieving materials and it holds great potential for applications in adsorptive separation.

A Kinetic Model for GaN Growth

1997 ◽  
Vol 482 ◽  
Author(s):  
D. D. Koleske ◽  
A. E. Wickenden ◽  
R. L. Henry ◽  
W. J. Desisto ◽  
R. J. Gorman
Keyword(s):  
Boundary Layer ◽  
Kinetic Model ◽  
Gas Phase ◽  
Smooth Surface ◽  
Growth Conditions ◽  
Desorption Kinetics ◽  
Optical And Electrical Properties ◽  
High Quality ◽  
Adsorption Desorption ◽  
Desorption Cycle

AbstractA kinetic model is presented to explain GaN growth. The model is based on established values for the N and Ga desorption kinetics and well founded assumptions on the adsorption and decomposition of the N and Ga containing precursors. When grown on similar nucleation layers, it is shown that high quality GaN films are achieved when the V/III ratio is chosen to be slightly larger than the Ga and N desorption rates. The model is verified by comparing the structural, optical, and electrical properties of the GaN to the growth temperature and V/III ratio. The model explains several features of GaN growth including, growth conditions for smooth surface morphology, growth conditions for highly resistive GaN, and a possible explanation for the origin of Ga and N vacancies in GaN. Based on the growth model, ordering of the GaN during growth is achieved via an adsorption/desorption cycle where Ga and N containing species are exchanged between the gas phase boundary layer and the solid surface. Consequences of the model on establishing growth conditions and run-to-run reproducability are also discussed.

Water-soluble polymeric particle embedded cryogels: Synthesis, characterisation and adsorption of haemoglobin

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Kadir Erol ◽  
Melda Bolat Bülter ◽  
Dursun Ali Köse ◽  
Hatice Kaplan Can
Keyword(s):  
Copper Ions ◽  
Langmuir Model ◽  
Water Soluble ◽  
Hydroxyethyl Methacrylate ◽  
Adsorption Ability ◽  
Adsorption Interaction ◽  
Polymeric Particle ◽  
Adsorption Desorption ◽  
Desorption Cycle ◽  
Soluble Poly

Abstract Making cryogels, which are among today’s accepted adsorbents, more functional with different methods, has been one of the subjects spent overtime. In this study, water-soluble poly(maleic anhydride-alt-acrylic acid) polymer embedded in poly(2-hydroxyethyl methacrylate) cryogels. Copper ions were then immobilised to this structure, and this polymer was used for adsorption of haemoglobin from aqueous systems. Adsorption interaction was carried out on an electrostatic basis, and approximately 448.62 mg haemoglobin/g polymer adsorption capacity value was obtained. It was found that the same material has managed to maintain its adsorption ability by 90.3% even after the use of it five times in the adsorption/desorption cycle. The adsorption interaction was determined to be appropriate for the Langmuir model by isotherm studies. The change in Gibbs free energy value was calculated as −2.168 kJ/mol.

Phosphorus effect on Zn adsorption–desorption kinetics in acid soils

Chemosphere ◽  
2011 ◽  
Vol 83 (7) ◽  
pp. 1028-1034 ◽  
Author(s):  
Cristina Pérez-Novo ◽  
David Fernández-Calviño ◽  
Alipio Bermúdez-Couso ◽  
José E. López-Periago ◽  
Manuel Arias-Estévez
Keyword(s):  
Acid Soils ◽  
Desorption Kinetics ◽  
Adsorption Desorption

Th-MOF showing six-fold imide-sealed pockets for middle-size-separation of propane from nature gas

2021 ◽  
Author(s):  
Feng Luo ◽  
Li Wang ◽  
Lele Gong ◽  
Wansheng Jia ◽  
Rajamani Krishna ◽  
...  
Keyword(s):  
Selective Adsorption ◽  
Supramolecular Interactions ◽  
Separation Mechanism ◽  
Ideal Solution ◽  
Light Alkanes ◽  
Size Separation ◽  
Direct Separation ◽  
Nature Gas ◽  
Breakthrough Experiments ◽  
Size Based Separation

Abstract Separation of propane from nature gas is of great importance to industry. However, in light of size-based separation, there still lacks effective method to directly separate propane from nature gas, due to the comparable physical properties for these light alkanes (C1-C4) and the middle size of propane. In this work, we found that a new Th-MOF could be an ideal solution for this issue. The Th-MOF takes UiO-66-type structure, but with the pocket sealed by six-fold imide groups; this not only precisely reduces the size of pocket to exactly match propane, but also enhances the host-guest interactions through multiple supramolecular interactions. As a result, highly selective adsorption of propane over methane, ethane, and butane was observed, implying unique middle-size separation. The actual separation was confirmed by breakthrough experiments, and it is found that both relatively smaller molecules (methane and ethane) and relatively bigger molecules (butane) break through the Th-MOF column within 10 min/g, whereas propane with middle size can maintain very long retention time up to 80 min/g, strongly suggesting middle-size separation and its superior application in direct separation of propane from nature gas. The separation mechanism, as unveiled by both theoretical calculation and comparative experiments, is due to the six-fold imide-sealed pockets that could effectively distinguish propane from other light alkanes through both size effect and host-guest interactions.

scholarly journals Activated Adsorption/Desorption of Cyclohexane over Activated Carbon Fiber with Molecular Sieving Property

TANSO ◽  
1994 ◽  
Vol 1994 (163) ◽  
pp. 115-118
Author(s):  
Yusaku Sakata ◽  
Takemi Namba ◽  
Yoshiaki Inoue ◽  
Eiji Tanaka ◽  
Shigeaki Kasaoka
Keyword(s):  
Activated Carbon ◽  
Carbon Fiber ◽  
Activated Carbon Fiber ◽  
Adsorption Desorption ◽  
Molecular Sieving

MODELING ADSORPTION/DESORPTION KINETICS OF PESTICIDES IN A SOIL SUSPENSION

Soil Science ◽  
1988 ◽  
Vol 146 (4) ◽  
pp. 221-231 ◽  
Author(s):  
J. J. T. I. BOESTEN ◽  
L. J. T. VAN DER PAS
Keyword(s):  
Desorption Kinetics ◽  
Soil Suspension ◽  
Adsorption Desorption ◽  
Kinetics Of
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