scholarly journals A smart and responsive crystalline porous organic cage membrane with switchable pore apertures for graded molecular sieving

2022 ◽  
Author(s):  
Ai He ◽  
Zhiwei Jiang ◽  
Yue Wu ◽  
Hadeel Hussain ◽  
Jonathan Rawle ◽  
...  
Keyword(s):  
High Selectivity ◽  
Organic Dyes ◽  
Composite Membranes ◽  
Molecular Weights ◽  
Interfacial Synthesis ◽  
Two Phases ◽  
Molecular Separations ◽  
Fine Tune ◽  
High Rejection ◽  
Molecular Sieving

AbstractMembranes with high selectivity offer an attractive route to molecular separations, where technologies such as distillation and chromatography are energy intensive. However, it remains challenging to fine tune the structure and porosity in membranes, particularly to separate molecules of similar size. Here, we report a process for producing composite membranes that comprise crystalline porous organic cage films fabricated by interfacial synthesis on a polyacrylonitrile support. These membranes exhibit ultrafast solvent permeance and high rejection of organic dyes with molecular weights over 600 g mol−1. The crystalline cage film is dynamic, and its pore aperture can be switched in methanol to generate larger pores that provide increased methanol permeance and higher molecular weight cut-offs (1,400 g mol−1). By varying the water/methanol ratio, the film can be switched between two phases that have different selectivities, such that a single, ‘smart’ crystalline membrane can perform graded molecular sieving. We exemplify this by separating three organic dyes in a single-stage, single-membrane process.

Iono-molecular Separation with Composite Membranes II. Preparation and characterization of polysulphone and composite nanoparticles

2017 ◽  
Vol 68 (2) ◽  
pp. 203-209
Author(s):  
Hussam Nadum Abdalraheem Al Ani ◽  
Anca Maria Cimbru ◽  
Corneliu Trisca-Rusu ◽  
Szidonia Katalin Tanczos ◽  
Adriana Cuciureanu ◽  
...  
Keyword(s):  
Chemical Species ◽  
Composite Membranes ◽  
Ammonium Persulfate ◽  
Operating Pressure ◽  
Polysulfone Membrane ◽  
Polymeric Nanoparticle ◽  
Molecular Separation ◽  
Copper Complexation ◽  
Molecular Separations ◽  
Methyl Pyrrolidone

This paper illustrates the possibility of producing iono-molecular separations using ionic colloidal ultrafiltration membrane of polysulfone synthetic solutions of cupric ions and nitro phenols through ultrafiltration assisted by polymeric nanoparticle composites based on polysulfone. In the present work, in order to reduce the operating pressure and increase the flow of water we are using the process of ultrafiltration through a polysulfone membrane in N-methylpyrrolidone 10% prepared by coagulation in isopropanol. The nanoparticles needed in colloidal ultrafiltration had been obtained through the immersion technique of precipitation of a solution of 5% PSf in N-methyl pyrrolidone containing 3% aniline in lower alcohols: methanol, ethanol, and isopropanol, followed by the oxidation of the remaining aniline in a solution of 10% hydrochloric acid and ammonium persulfate. The Nanoparticles of polysulfone (NP-PSf) and The three obtained variants of nanoparticles composites (NP-PSf-PANI) were morphologically (SEM) and (AFM), structurally and compositionally (FTIR) characterized and the results show that nanoparticles polysulfone have a much lower range than the composites. The Possibility of copper complexation by both nitrophenols, and by nanoparticle surface probably lead to the formation of more stable aggregates in the supply, which can sufficiently justify the increased retention. The Retentions of the chemical species in question use in all the tests made the same series:R NP-PSf-PANI-M] R NP-PSf-PANI-E] R NP-PSf-PANI-P] R NP-PSf

Molecular sieving polymer for DNA/RNA separation in capillary electrophoresis

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744094 ◽  
Author(s):  
Chenchen Liu ◽  
Yoshinori Yamaguchi ◽  
Xiaoming Dou
Keyword(s):  
Capillary Electrophoresis ◽  
Small Rna ◽  
Polymer Concentration ◽  
Migration Time ◽  
Migration Behavior ◽  
Molecular Weights ◽  
Rna Fragments ◽  
Molecular Sieving

In capillary polymer electrophoresis, the property of polymer sieving matrix dominates the migration behavior of DNA/RNA. We investigated the capillary electrophoresis of RNA ranging from 100 nt to 10,000 nt in polyacrylamide (PA) solutions with different molecular weights (Mw) and different concentrations. We observed that the resolution length (RSL) of RNA fragments was improved and the migration time was prolonged, when polymer concentration was increased. The resolution for small RNA fragments ([Formula: see text]1000 nt) was improved with the increase of polymer concentration, whereas the large ones ([Formula: see text]3000 nt) became inseparable. In addition, we estimated the smallest resolvable nucleotide length (Ls) by the plot of RSL against RNA size.

Adhesion and protective properties of electrospun PVA/ES composites obtained by using spiral disk spinnerets

2016 ◽  
Vol 87 (14) ◽  
pp. 1685-1695 ◽  
Author(s):  
Chuchu Zhao ◽  
Yao Lu ◽  
Zhijuan Pan
Keyword(s):  
Composite Membranes ◽  
Air Permeability ◽  
Hot Press ◽  
Adhesion Properties ◽  
Protective Properties ◽  
Molecular Weights ◽  
Initial Modulus ◽  
Peeling Strength ◽  
Press Method ◽  
Nanofiber Web

The parameters of electrospinning polyvinylalcohol (PVA) of different molecular weights using spiral disk spinnerets were explored. Ethylene-propylene side-by-side (ES) nonwoven was used as the substrate. Electrospun PVA/ES composite membranes were fabricated by laminating a nanofiber web onto the nonwoven substrate via the hot-press method. The adhesion properties between the PVA nanofiber mat and the ES nonwoven were studied. The results showed that the adhesion properties were significantly affected by temperature, pressure, and processing time. The resultant composite membranes, when treated at 145℃ with a pressure of 100 Pa for 10 minutes, exhibited a preferable adhesion energy of 7.95 J/m2 and a maximum peeling strength of 20.17 cN, as well as a maximum air permeability of 73.92 dm3/(m2s). Simultaneously, the effect of electrospinning time on the characteristics of PVA/ES composites was also explored. The filtration efficiency increased with the prolongation of the electrospinning time, whereas the air permeability decreased. All of the samples were grade A in terms of the electrostatic half-life period (which was less than two seconds), and the softness slowly declined with the addition of nanofibrous layers. The breaking stress, the initial modulus, and the elongation were enhanced with the prolongation of electrospinning time.

Isolation of several fractions from human serum, inhibiting rabbit cartilage metabolism in vitro

1990 ◽  
Vol 122 (2) ◽  
pp. 277-282 ◽  
Author(s):  
Marc V. L. Du Caju ◽  
Raoul P. Rooman
Keyword(s):  
Human Serum ◽  
Thymidine Incorporation ◽  
Inhibitory Effect ◽  
Cartilage Metabolism ◽  
Molecular Weights ◽  
Rabbit Cartilage ◽  
Molecular Sieving

Abstract In contrast to the well characterized serum stimulators of cartilage metabolism, information is scarce on the nature of circulating inhibitors. Human serum was fractionated by molecular sieving chromatography on Sephadex G-200, G-75, G-50 and Biogel P-4 gels. Six fractions with molecular weights of 150, 45, 30, 16, 9 and 1.2 kD inhibited [35S]sulphate incorporation into rabbit cartilage segments. All fractions but the smallest one exhibited their inhibitory effect only in the serum-stimulated cartilage. The 1.2 kD fraction impaired [35S]sulphate and [3H]methyl-thymidine incorporation into the cartilage segments in both stimulated and basal conditions. A seventh inhibitory fraction corresponded to the serum salt peak.

scholarly journals Recent Developments in Nanoporous Graphene Membranes for Organic Solvent Nanofiltration: A Short Review

Membranes ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 793
Author(s):  
Yoon-Tae Nam ◽  
Junhyeok Kang ◽  
Jaedong Jang ◽  
Jun-Hyuk Bae ◽  
Hee-Tae Jung ◽  
...  
Keyword(s):  
Organic Solvent ◽  
Structural Characteristics ◽  
Single Layer ◽  
Composite Membranes ◽  
Short Review ◽  
Size Exclusion ◽  
Recent Developments ◽  
Nanoporous Graphene ◽  
Organic Solvent Nanofiltration ◽  
Molecular Sieving

Graphene-based membranes are promising candidates for efficient organic solvent nanofiltration (OSN) processes because of their unique structural characteristics, such as mechanical/chemical stability and precise molecular sieving. Recently, to improve organic solvent permeance and selectivity, nanopores have been fabricated on graphene planes via chemical and physical methods. The nanopores serve as an additional channel for facilitating ultrafast solvent permeation while filtering organic molecules by size exclusion. This review summarizes the recent developments in nanoporous graphene (NG)-based membranes for OSN applications. The membranes are categorized depending on the membrane structure: single-layer NG, multilayer NG, and graphene-based composite membranes hybridized with other porous materials. Techniques for nanopore generation on graphene, as well as the challenges faced and the perspectives required for the commercialization of NG membranes, are also discussed.

scholarly journals Mixed Membranes Comprising Carboxymethyl Cellulose (as Capping Agent and Gas Barrier Matrix) and Nanoporous ZIF-L Nanosheets for Gas Separation Applications

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1340 ◽  
Author(s):  
Fang Zhang ◽  
Jing Dou ◽  
Hui Zhang
Keyword(s):  
Gas Separation ◽  
Carboxymethyl Cellulose ◽  
Aqueous Suspension ◽  
Composite Membranes ◽  
Gas Permeation ◽  
Zinc Salt ◽  
High Dispersion ◽  
Gas Barrier ◽  
Synthetic Process ◽  
Molecular Sieving

Two-dimensional metal–organic framework (MOF) nanosheets with molecular sieving properties and unique dimensional advantages are highly desired as polymer fillers for gas separation applications. Regarding polymer-supported MOF membranes, it is crucial to enhance the adhesion between the polymeric substrate and the MOF component and avoid MOF particle agglomeration. In this study, hydrophobic, embedded nanoporous nanosheets of a 2D zeolitic imidazolate framework synthesized using zinc salt and 2-methylimidazole (Hmim) aqueous solution (ZIF-L) were incorporated into a carboxymethyl cellulose (CMC) solution to form a steady mixed aqueous suspension through one-step solution blending. This prepared the composite membranes with a fine dispersion of ZIF-L nanosheets (up to loadings of 52.88 vol %) and good adhesion within the highly dense structural CMC matrix due to the strong interactions between ZIF-L and CMC, as confirmed by FTIR, Zeta potential, XPS, and SEM analysis. The potential advantages of CMC over classic polymer matrices used for gas separation mainly include: (a) Good interaction, (b) high dispersion of ZIF-L nanosheets, (c) the gas barrier nature of the CMC membrane, and (d) a facile water-based synthetic process. Based on the molecular sieving effect of ZIF-L and the gas barrier nature of the CMC matrix, gas permeation tests (H2, CO2, N2, CH4) of the mixed membrane showed a great improvement in gas selectivities compared with the CMC membrane and the reported pure ZIF membranes.

Tuning molecular sieving channels of layered double hydroxides membrane with direct intercalation of amino acids

2018 ◽  
Vol 6 (35) ◽  
pp. 17148-17155 ◽  
Author(s):  
Naixin Wang ◽  
Zheng Huang ◽  
Xiaoting Li ◽  
Jie Li ◽  
Shulan Ji ◽  
...  
Keyword(s):  
Amino Acids ◽  
Layered Double Hydroxide ◽  
Layered Double Hydroxides ◽  
Composite Membranes ◽  
Double Hydroxide ◽  
Double Hydroxides ◽  
Molecular Sieving

A facile and feasible approach was developed to prepare layered double hydroxide (LDH) composite membranes by using amino acids as intercalation molecules.

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