Unusual trend of increasing selectivity and decreasing flux with decreasing thickness in pervaporation separation of ethanol/water mixtures using sodium alginate blend membranes

Flynn, Eoin J.; Keane, Donal A.; Holmes, Justin D.; Morris, Michael A.

doi:10.1016/j.jcis.2011.12.022

Cited by 12 publications

(4 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The strong absorption at 1590 cm −1 corresponds to the CO stretching of alginate and is the characteristic peak of the ionic bonded carboxylic group of alginate. 33,35,36 Similar peak is observed for the blend membranes as well but with low intensity. However, this type of absorption is found to be absent in PVA spectrum.…”

Section: Resultssupporting

confidence: 74%

“…An additional medium peak at 2900–3000 cm –1 is appeared for PVA; whereas, it diminishes in blended membranes’s spectra, expressing the hydrogen bonded OH groups and CH stretching respectively. The strong absorption at 1590 cm –1 corresponds to the CO stretching of alginate and is the characteristic peak of the ionic bonded carboxylic group of alginate. ,, Similar peak is observed for the blend membranes as well but with low intensity. However, this type of absorption is found to be absent in PVA spectrum.…”

Section: Results and Discussionsupporting

confidence: 54%

“…At a particular temperature, the decrease in flux and a decrease in the permeate methanol concentration (increase in α value) for annealed membrane is due to the decrease in the free volume and compaction of the membrane morphology upon annealing. It is well-known that the amorphous region of the polymer is responsible for the transportation of molecular species, and a decrease in this region is found after annealing due to the rising of crystallanity as shown in XRD and SEM data (Figures and ), leading to a decrease in flux and an increase in separation factor that is more specifically attributed to the decrease in d -spacing of the annealed membrane. However, for annealed membranes, the separation factor was not shown to be increasing with the rise in temperature (unlike the nonannealed membrane) because of the lack of further densification of the membrane under the operating conditions .…”

Section: Results and Discussionmentioning

confidence: 89%

See 2 more Smart Citations

Vapor Permeation Separation of Methanol–Water Mixtures: Effect of Experimental Conditions

Bano

Mahmood

Lee

2013

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

Methanol–water separation by membrane has always remained a big challenge for membrane researchers. In this study, sodium alginate (NaAlg)/poly(vinyl alcohol)(PVA) membranes were prepared with a blending ratio of 80/20 wt % for the separation of water–methanol mixtures. The prepared membranes were then complexed with calcium ions followed by annealing at the 110 °C to modulate their morphology and consequently to enhance the separation performance. The change in morphology brought about by annealing was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), while thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to examine the stability of the membranes. Both nonannealed and annealed membranes were employed to investigate the vapor permeation separation characteristics of methanol–water mixture. The effect of operating temperature, feed concentration, and annealing time on permeation rate and separation factor was investigated. Before annealing the permeation rate and separation factor was found to increase with a rise in operating temperature while, after annealing, the separation factor was decreased with temperature. As expected, the maximum permeation rate was observed for a feed having high water contents but interestingly a maximum in separation factor was observed for a feed with moderate water contents because of the plasticization effect of the membrane. Moreover, the annealing process was found to have an enormous effect on the membrane morphology and therefore on the separation performances. It is argued that the heat treatment is a remarkable way to tune the morphology of the NaAlg/PVA membrane and to enhance its vapor permeation separation characteristics for methanol–water mixture. Eventually, a separation factor of as high as infinity can be achieved at 40 °C for 80 wt % methanol using a 12 h NaAlg/PVA annealed membrane.

show abstract

Section: Resultssupporting

confidence: 74%

Section: Results and Discussionsupporting

confidence: 54%

Section: Results and Discussionmentioning

confidence: 89%

See 1 more Smart Citation

Vapor Permeation Separation of Methanol–Water Mixtures: Effect of Experimental Conditions

Bano

Mahmood

Lee

2013

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

show abstract

“…The performance of polymeric membranes regarding water flux can be correlated with membrane free volume (fv) and fv distribution . Positron techniques are widely used for the comparison of material properties as a function of fv in a wide variety of polymeric materials, including membranes .…”

Section: Resultsmentioning

confidence: 99%

Positron annihilation lifetime spectroscopy study of polyvinylpyrrolidone‐added polyvinylidene fluoride membranes: Investigation of free volume and permeation relationships

Eren

Guney

et al. 2020

Journal of Polymer Science

View full text Add to dashboard Cite

Polyvinylidene fluoride (PVDF) membranes were prepared via the phase inversion method from casting solutions containing PVDF, dimethylformamide (DMF), and polyvinylpyrrolidone (PVP) as pore former. PVP was used in the casting solution in a range of 0–5 wt % and extracted. The effect on membranes of using PVP in the casting process was analyzed by X‐ray diffraction, differential scanning calorimetry, scanning electron microscopy, viscosity, and water permeability techniques. With an increase of PVP from 0 to 5 wt %, the PVDF casting solution viscosities increased from 858 to 1148 cP; the resulting PVDF membrane thickness increased; and the crystallinity of PVDF membranes decreased from 40.0 to 33.3%, which indicates that the addition of PVP inhibits the degree of crystallization in the PVDF membranes. SEM results revealed the shape and size of macropores in the membranes; these macropores changed after PVP addition to the casting solutions. The impact of structural changes on free‐volume properties was evaluated using positron annihilation lifetime spectroscopy (PALS) studies. PALS analysis indicated no effect on the average radius (~3.4 Å) of membrane free‐volume holes from the addition of PVP to the casting solution. However, the percentage of o‐Ps pick‐off annihilation intensity, I3, increased from 1.7 to 5.1% with increased PVP content. Further, increasing the PVP content from 0.5 to 5% resulted in an increased final pure water permeability flux. For instance, the 210 min flux for a 14% PVDF + 0.5% PVP membrane was found to be 3.3 times greater than a control membrane having the same PVDF concentration. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 589–598

show abstract

Alginate‐based Films and Membranes: Preparation, Characterization and Applications

2016

Nanostructured Polymer Membranes

View full text Add to dashboard Cite

Unusual trend of increasing selectivity and decreasing flux with decreasing thickness in pervaporation separation of ethanol/water mixtures using sodium alginate blend membranes

Cited by 12 publications

References 17 publications

Vapor Permeation Separation of Methanol–Water Mixtures: Effect of Experimental Conditions

Vapor Permeation Separation of Methanol–Water Mixtures: Effect of Experimental Conditions

Positron annihilation lifetime spectroscopy study of polyvinylpyrrolidone‐added polyvinylidene fluoride membranes: Investigation of free volume and permeation relationships

Alginate‐based Films and Membranes: Preparation, Characterization and Applications

Contact Info

Product

Resources

About