Pervaporative Dehydration of Organic Solvents

137

ABSTRACT:The blend membranes of sodium alginate and poly(vinyl alcohol) have been prepared by physical mixing in different ratios (75, 50, and 25%) of sodium alginate with poly(vinyl alcohol). The membranes were crosslinked with glutaraldehyde and used in the pervaporation separation of water ϩ isopropanol mixtures at 30°C. The crosslinking reaction was confirmed by Fourier transform infrared spectra. Permeation flux increased with an increase in mass % of water in the feed mixture as well as with an increase in the amount of poly(vinyl alcohol) in the blend, but separation selectivity decreased. Diffusion coefficients of water ϩ isopropanol mixtures have been calculated using the Fick's equation from the sorption data. Arrhenius activation parameters were calculated for 10 mass % of water in the feed mixture using the values of flux and diffusion coefficients obtained at 30, 40, and 50°C. The diffusion and pervaporation results have been explained on the basis of solution-diffusion principles.

Section: Resultsmentioning

confidence: 98%

Syntheses and characterization of blend membranes of sodium alginate and poly(vinyl alcohol) for the pervaporation separation of water + isopropanol mixtures

Kurkuri

Toti

Aminabhavi

2002

137

“…If activation energy is positive, then permeation flux increases with increasing temperature, which is generally observed in PV experiments. 29,30 The Arrhenius plots of log J P versus 1000/T and log D i versus 1000/T for flux of water and isopropanol are linear (not displayed to minimize the number of plots), signifying that temperature dependence of permeation and diffusion followed the Arrhenius trend. Apparent activation energy data for permeation, E P , and diffusion, E D , calculated from the slopes of straight lines of the Arrhenius plots by using the leastsquares method are presented in Table IV.…”

Section: Figurementioning

confidence: 99%

Synthesis and characterization of polyacrylamidegrafted sodium alginate membranes for pervaporation separation of water + isopropanol mixtures

Toti¹,

Aminabhavi²

2004

Polyacrylamide-grafted-sodium alginate copolymers were prepared by persulfate-induced radical polymerization by using polymer-to-monomer ratios of 2 : 1 and 1 : 1. Polymers were characterized by Fourier transform infrared spectroscopy, differential thermal analysis, and viscosity. Membranes were prepared from the polymers, crosslinked with glutaraldehyde, and used in the pervaporation separation of water ϩ isopropanol mixtures at 30°C. Equilibrium swelling experiments were performed for mixtures containing 10 to 80 mass % of water in the feed. Both the grafted copolymer membranes were ruptured while separating 10 mass % of water in the feed mixture. However, beyond 20 mass % of water in the feed mixture, flux increased with increasing grafting ratio, while selectivity decreased. Pervaporation separation experiments were carried out at 30, 40, and 50°C for 20 mass % of water in the feed mixture. By increasing the temperature, flux increased, whereas selectivity decreased. Arrhenius activation parameters for pervaporation and diffusion decreased with increasing grafting ratio of the membranes.

“…Crosslinking with aldehyde acids was carried out by Burshe and coworkers. 3,7 Besides PVA, different cellulosic derivatives can be used. These are very effective for the separation of strongly hydrophilic compounds.…”

Section: Introductionmentioning

confidence: 99%

“…The selective separation of water from aqueous mixtures of MP or the dehydration of MP can be carried out with different membranes that contain polar groups, either in the backbone or as pendant moieties. For the pervaporative dehydration of such a mixture, cellophane 6 and PVA and PVA-based membranes 7,8 can be used. Cellophane contains a polar oxygen atom in its glucosidic unit, as well as OOH, OCH 2 OH groups as side groups, and PVA is a well-known hydrophilic polymer, containing OOH groups as pendant moieties on the ethylene unit.…”

Section: Introductionmentioning

confidence: 99%

Pervaporative separation of a 1‐methoxy propanol and water mixture

Mandal

Pangarkar

2002

ABSTRACT:The pervaporative dehydration of ether derivatives of alcohol, such as 1-methoxy propanol (MP) and water mixtures, was studied with polyimide (PI), cellophane, poly(vinyl alcohol) (PVA), cellulose diacetate (CDA), cellulose triacetate, two separate blends of cellulose acetate and CDA with cellulose acetate propionate, and PVA crosslinked with multifunctional crosslinkers. The effects of different substitution derivatives of cellulosic materials were investigated. Membranes of PVA and citric acid and of PVA and maleic anhydride were studied with respect to the effect of the crosslinker and its loading. Among all the hydrophilic membranes, PI gave the best selectivity but poor flux. Poly-(dimethylsiloxane) (PDMS) and linear low-density polyethylene (LLDPE) membranes were invoked for the selective permeation of comparatively weaker hydrophilic components. PDMS showed acceptable results for MP separation in terms of both flux and selectivity. LLDPE yielded better selectivity but very poor MP flux. All these membranes were stable, and no changes in their properties were observed over the entire range of concentration at 30°C.