Effect of thermochemical treatment on the surface morphology and hydrophobicity of heterogeneous ion-exchange membranes

Васильева, В. И.; Pismenskaya, Natalia; Акберова, Э. М.; Nebavskaya, K. A.

doi:10.1134/s0036024414080317

Cited by 47 publications

(37 citation statements)

References 27 publications

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“…The SEM images of the surface of a membrane from the reversal electrodialyzer are presented for sides 1 and 2 facing the electrode and the neighboring compartment, respectively. The possibility for pressure control in the chamber with the sample under study made it possible to study membranes in the swollen state in the low-vacuum mode [51,52]. The information about the chemical composition of the surface or section of the membrane was obtained by mapping the elemental composition using an energy dispersive spectrometer.…”

Section: Methods For Investigation Of the Equilibrium Transportmentioning

confidence: 99%

Diagnostics of the Structural and Transport Properties of an Anion-Exchange Membrane MA-40 after Use in Electrodialysis of Mineralized Natural Waters

Васильева

Акберова

Kostylev

et al. 2019

Membr. Membr. Technol.

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Changes in the structural and transport characteristics of MA-40 anion-exchange membranes after operation in industrial electrodialysis apparatuses have been assessed. Causes for the deterioration of operational properties by the action of various factors in the process of demineralization and concentration of natural waters have been revealed. Samples of the anion-exchange membrane after long-term operation in the working stack of an electrodialysis concentrator, as well as samples taken out from the electrode compartment of the electrodialysis reversal apparatus, have been studied. The most significant change in the structure of the membrane taken out from the electrodialyzer concentrator is an increase in macroporosity, which is the main reason for the growth in the electrical conductivity and water content against the background of a loss of ion-exchange capacity and selectivity. The formation of poorly soluble carbonates and hydroxides both on the surface and in the bulk of a membrane from the electrode compartment of the reversal electrodialyzer leads to the blocking of the functional groups and transport channels, decrease in electrical conductivity, and complication of transport processes.

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Section: Methods For Investigation Of the Equilibrium Transportmentioning

confidence: 99%

Diagnostics of the Structural and Transport Properties of an Anion-Exchange Membrane MA-40 after Use in Electrodialysis of Mineralized Natural Waters

Васильева

Акберова

Kostylev

et al. 2019

Membr. Membr. Technol.

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“…The study of the morphology of the membrane surface was performed by scanning electron microscopy (SEM) using a microscope JSM-6380 LV (JEOL, Tokyo, Japan). In the chamber with the sample under study, the pressure was adjustable, which allowed investigating membranes in the low-vacuum mode in the working (swollen) state [16,28]. Electron-microscopic photography of the samples was carried out in the low-vacuum mode using backscattered electrons at an accelerating voltage of 20 kV.…”

Section: Scanning Electron Microscopymentioning

confidence: 99%

“…The expression for recalculating the fraction of the conducting surface of the dry membrane with respect to the swollen sample was obtained under the assumption that the increase in the linear dimensions of the membranes in the process of swelling occurs mainly due to an increase in the size of the ion exchange material. A low-vacuum SEM allows visualizing of the surface and cross-section structure of ion-exchange membranes of various types in the swollen state [9,16,28,29].…”

Section: Introductionmentioning

confidence: 99%

A Study of Ralex Membrane Morphology by SEM

et al. 2019

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A comparative analysis of the effect of the manufacturing technology of heterogeneousion-exchange membranes Ralex CM Pes manufactured by MEGA a.s. (Czech Republic) on the structural properties of their surface and cross section by SEM was carried out. The CM Pes membrane is a composite of a sulfonated ion-exchanger with inert binder of polyethylene and reinforcing polyester fiber. In the manufacture of membranes Ralex the influence of two factors was investigated. First, the time of ion-exchange grain millingvaried at a constant resin/polyethylene ratio. Second, the ratio of the cation-exchanger and the inert binder of polyethylene varied. It has been found that the membrane surface becomes more electrically homogeneous with the growth of the ion-exchanger loading and a decrease in its particle size. With an increase in the milling time of resin grainsfrom 5 to 80 min a more than 1.5-fold decrease in their radius and in the distance between them was revealed.Besides, there is a 1.5-fold decrease in the fraction, as well as in the size of pores and structure defects. The fraction of the ion-exchange phase on the membrane surface decreases by 7%. With an increase in the resin loading from 45 to 70 wt %, the growth of the fraction of conducting regions on the surface is almost twofold, while their sizes remain practically unchanged. More significant changes in the surface structure of the studied membranes are established in comparison with the cross section. An increase in the resin content in the membranes from 45 to 70 wt % corresponds to a 43% increment of its fraction on the cross-section.The increase in the ion-exchanger content of Ralex membranes is accompanied by the growth of the fraction of macropores and structure defects on the membrane surface by 70% and a twofold decrease in the distance between conducting zones.

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“…The most common scheme for the regeneration of membrane arrays in ED processes used in the food industry is a daily sequential washing with alkali and acid solutions [18,19] or perchlorate solutions [20]. However, long-term use of these solutions leads to the degradation of ion-exchange membranes and the loss of their ability to selectively separate ions [20][21][22]. In addition, there is a need to create additional sewage treatment facilities in order to preclude the discharge of the wastewater into the environment.…”

Section: Introductionmentioning

confidence: 99%

Application of Sodium Chloride Solutions to Regeneration of Anion-Exchange Membranes Used for Improving Grape Juices and Wines

Nevakshenova

Сарапулова

Nikonenko

et al. 2019

Membr. Membr. Technol.

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Membrane technologies, in particular, electrodialysis, are increasingly being used to stabilize and condition juices and wines. This work is aimed at finding environmentally appropriate "mild" methods for regeneration of anion-exchange membranes that are used in these processes. It has been shown that the fouling of anion-exchange membranes by grape wine components leads to an increase in both their electrical resistance by 30 or more times and thickness. The behavior of the resistance and its values in grape juice and wine for the investigated membranes are similar, apparently, due to the similar chemical composition of these liquid media. Treatment with NaCl solutions leads to partial degradation of the formed colloidal particles as a result of to the salting-out effect. The higher the salt concentration in the regenerating solution, the closer the conductivity values of the regenerated membranes are to the original values. The thinner the membrane and the larger its pores, the faster and more complete the regeneration process. If the contact time of anionexchange membranes with wine does not exceed 70 h, salt regeneration can almost completely restore their selectivity. For example, in the case of homogeneous AMX-Sb membrane, the transport numbers of the counterion Cl − in the initial and regenerated samples differ by no more than 1%. In the case of heterogeneous MA-41P membrane, this difference increases to 3%.

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Effect of thermochemical treatment on the surface morphology and hydrophobicity of heterogeneous ion-exchange membranes

Cited by 47 publications

References 27 publications

Diagnostics of the Structural and Transport Properties of an Anion-Exchange Membrane MA-40 after Use in Electrodialysis of Mineralized Natural Waters

Diagnostics of the Structural and Transport Properties of an Anion-Exchange Membrane MA-40 after Use in Electrodialysis of Mineralized Natural Waters

A Study of Ralex Membrane Morphology by SEM

Application of Sodium Chloride Solutions to Regeneration of Anion-Exchange Membranes Used for Improving Grape Juices and Wines

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