Investigation of fine-structure of polyamide thin-film composite membrane under swelling effect by positron annihilation lifetime spectroscopy and molecular dynamics simulation

Pervaporation has been regarded as a promising separation technology in separating azeotropic mixtures, solutions with similar boiling points, thermally sensitive compounds, organic-organic mixtures as well as in removing dilute organics from aqueous solutions. As the pervaporation membrane is one of the crucial factors in determining the overall efficiency of the separation process, this article reviews the research and development (R&D) of polymeric pervaporation membranes from the perspective of membrane fabrication procedures and materials.

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“…of the membrane which could be estimated through the Bondi's method [40] or the positron annihilation spectroscopy (PAS) [41][42][43][44][45].…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Recent membrane development for pervaporation processes

Ong

Shi

et al. 2016

Progress in Polymer Science

479

205

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“…The ''free volume'' in ion-exchange membranes can be also estimated from Positron Annihilation Lifetime Spectroscopy (PALS). PALS has been developed as a powerful tool for the microscopic structure characteri zation of a variety of polymer such as poly(ethylene oxide) films [40,41], Nafion membranes [42,43] or thin film composite polyamide nanofiltration membranes [44,45]. This method correlated the lifetime and relative intensity of positrons (anti-electrons) annihilating in the free volume of the membrane with the free volume element size and the fraction of free volume.…”

Section: Electrolytementioning

confidence: 99%

Influence of the ionic composition on the diffusion mass transfer of saccharides through a cation-exchange membrane

Galier¹,

Savignac²,

Balmann³

2013

Separation and Purification Technology

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Recent studies have pointed out that the presence of salts can change significantly the membrane process performances because of the resulting modification of the neutral solutes transfer through the membrane. The influence of the ionic composition on the transfer of neutral solutes through membranes could be explained by a modification of the membrane properties, due to electrostatic effects, by a modification of the solute radius, likely due to its dehydration induced by the electrolyte, or more probably by a combination of both. This study deals with the investigat ion of the mechanisms governing the mass transfer of neutral species through an ion-exchange membrane used in electrodialysis, CMX, with a focus on the role of ions. The mass transfer of various saccharides (xylose, glucose and sucrose) as well as the solvent transfer in different electrolytic solutions (NaCl, NH 4 Cl, CaCl 2 and MgCl 2) was studied in a diffusion regime. A specific procedure has been used to dissociate the solvent or solute fluxes variations due to the modifications of the solute properties and of the membrane material induced by the electrolyte. The results showed that the transfer modification is mainly due to the influence of the electrolyte on the membrane properties, which is fixed by the membrane soaking. A quantitative correlation has been established between the solvent and solute transfer and the hydratio n number of the membrane counterion. In presence of electrolyte, the saccharide mass transfer increased but the impact of the presence of electrolyte is much less than the one of membrane soaking. However, in this case, a relationship has been also established between the increase of the saccharide mass transfer and the cation hydration state.

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“…Minimizations stages were accomplished operating the Smart Minimization mode that switches from steepest-descent to conjugated gradient and then to the Newton–Raphson method as the energy derivatives decrease in order to speed the computation [14] , [15] . For each polymer, the repeating unit was first built and its geometry optimized by energy minimization using the COMPASS (condensed-phase optimized molecular potential for atomistic simulation studies) force field [16] , [17] . Then, the amorphous cell module was employed to fold one aromatic polyamide chain with repeating units into a periodic unit cell at ambient temperature to generate 10 configurations shown in Fig.…”

Section: Experimental Design Materials and Methodsmentioning

confidence: 99%

Data for molecular recognition between polyamide thin film composite on the polymeric subtract by molecular dynamic

et al. 2019

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This paper focus to examine the best molecular interaction between Polyamide Thin Film Composite (PA TFC) layers with different properties of the support membrane. The support membrane of Nylon 66 (N66) and Polyvinylidene fluoride (PVDF) was chosen to represent the hydrophilic and hydrophobic model respectively in the Molecular Dynamic (MD) simulation. The Condensed-Phase Optimized Molecular Potential for Atomistic Simulation Studies (COMPASS) force field was used with the total simulation runs were set 1000 picoseconds run production ensembles. The temperature and pressure set for both ensembles were 298 K and 1 atm respectively. The validity of our model densities data was check and calculated where the deviation must be less than 6%. The comparison between hydrophobic and hydrophilic of the support membrane data was examined by the distance and magnitude of intensity of the Radial Distribution Function (RDF's) trends.

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Investigation of fine-structure of polyamide thin-film composite membrane under swelling effect by positron annihilation lifetime spectroscopy and molecular dynamics simulation

Cited by 43 publications

References 40 publications

Recent membrane development for pervaporation processes

Recent membrane development for pervaporation processes

Influence of the ionic composition on the diffusion mass transfer of saccharides through a cation-exchange membrane

Data for molecular recognition between polyamide thin film composite on the polymeric subtract by molecular dynamic

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