Preparation and characterization of HY zeolite-filled chitosan membranes for pervaporation separation

ABSTRACT:The mixed matrix membranes (MMMs) were developed from a composite of hydrophobic-hydrophilic NR-blend-PAA with zeolite 4A. A separation performance of the MMMs was investigated by performing the pervaporation dehydration of water-ethanol mixtures. The results showed a dramatically greater flux of water than the ethanol flux indicating that the developed membranes were highly water-selective. Upon incorporating of zeolite 4A, the flux and separation factor were significantly improved. Increasing the water content in the water-ethanol feed mixtures resulted in an increase in both water and ethanol fluxes leading to a decrease in water separation factor. Similarly a flux-separation factor trade-off was observed as raising feed temperature. The water permeance, however, declined when either the feed water concentration or the feed temperature increased. This suggests that the driving force, i.e. the partial pressure difference, has a pronounced effect on the water flux enhancement. Conversely, the driving force was less influential on the ethanol permeance. The activation energies of the permeations obtained from the Arrhenius plots, showed the lower activation energies of water permeation than those of ethanol permeation; this is because water molecules experiences less restrictive passage through the membranes compared with ethanol molecules.

Section: Results and Dicussionmentioning

confidence: 99%

Highly water‐selective mixed matrix membranes from natural rubber‐blend‐poly(acrylic acid) (NR‐blend‐PAA) incorporated with zeolite 4A for the dehydration of water–ethanol mixtures through pervaporation

Amnuaypanich

Naowanon

Wongthep

et al. 2012

“…At higher concentration of water in the feed, the membranes swell greatly due to the formation of a strong interaction between the membrane and water molecules. This might have led to allow water molecules to pass through the membranes 36. As a result, flux of water increases drastically at higher concentration of water in the feed, irrespective of the amount of zeolite loading in the membrane matrix.…”

Section: Resultsmentioning

confidence: 99%

Preparation and characterization of 4A zeolite‐filled mixed matrix membranes for pervaporation dehydration of isopropyl alcohol

Prasad

Swamy²,

Sudhakar

et al. 2011

Sodium carboxymethylcellulose/poly (vinyl alcohol) mixed matrix membranes filled with different amounts 4A zeolite (0,5,10,15, and 20 wt %) were prepared by solution casting method. Prepared membranes were crosslinked with GA and used for pervaporation dehydration of isopropyl alcohol of different feed mixtures at 35 C. On increment in zeolite content in the membrane it was found the improvement in the performance of the membrane, due to its hydrophilic nature and molecular sieving effect in addition to its favorable interaction with hydrophilic sodium carboxymethylcellulose and polyvinyl alcohol. The structure and chemical constituents of the MMM's were investigated by attenuated total reflectance Fourier transform infrared spectroscopy. Thermal stability of the membranes was assessed by DSC and TGA techniques. Crystallinity of the membranes was assessed using X-ray diffraction, and the morphological properties were assessed by scanning electron microscopy. Mechanical properties were also carried out to determine the tensile strength and % of elongation at break using universal testing machine. It was found that the mechanical strength increases with increase in the zeolite content upto 15 wt % of zeolite with an optimum tensile strength of 113.31 N/mm 2 . Pervaporation was carried out to asses the membrane performance, the highest flux and selectivity obtained is 0.584 kg/m 2 /h and 6945 for NaCMCA20 and NaCMCA15, respectively, for a feed composition containing 17.5 and 10 wt % of water in the feed and further swelling studies also supporting the pervaporation results.

“…Recently, many investigators17–19 have been directed to chitosan as a PV membrane material because of its high affinity toward water, good film‐forming properties, functional groups that can be easily modified, and good mechanical and chemical stability. However, the performance of pure chitosan membrane is not satisfactory at higher concentration of water because of a large free‐volume available between the molecular chains 20, 21. Great efforts are therefore being attempted to improve the membranes performance by blending it with other polymers such as polysulfone,22, 23 poly(vinyl alcohol) (PVA),24 and silk fibroin,25 or by crosslinking it with glutaraldehyde22 and sulfosuccinic acid 26.…”

Section: Introductionmentioning

confidence: 99%

“…Similarly, inorganic reinforcement such as incorporation of selective zeolite into chitosan membrane is another way of modification of membrane. For instance, Gao et al27 and Chen et al,21 respectively, studied the PV separation of hydrophilic zeolite‐filled PVA and chitosan membranes for organic‐water system. In our previous research work, we have reported hydrophobic zeolite‐filled PVA membrane13 and hydrophilic zeolite‐filled sodium alginate membrane14 for the separation of water–isopropanol mixtures.…”

Section: Introductionmentioning

confidence: 99%

Dehydration of THF‐water mixtures using zeolite‐incorporated polymeric membranes

Varghese

Kittur

2008

Using a solution technique, polymeric composite membranes were prepared by the incorporation of NaY zeolite into chitosan. The resulting membranes were tested for pervaporation separation of water-tetrahydrofuran mixtures in a temperature range of 30-50 C. The effect of membrane swelling on the separation performance was studied by varying the water composition in the feed from 5 to 30 mass %. Pervaporation data demonstrated that both flux and selectivity increased simultaneously with increasing zeolite content in the membrane. This was explained on the basis of enhancement of hydrophilicity, selective adsorption, and establishment of molecular sieving action. It was found that both total flux and flux of water are close to each other, suggesting that the developed membranes are highly selective toward water. The membrane containing the highest loading of zeolite exhibited the highest separation selectivity of 2140 with a substantial water flux of 16.88 Â 10 À2 kg/(m 2 h) at 30 C for 5 mass % of water in the feed. From the temperature dependency of diffusion and permeation data, the Arrhenius activation parameters were estimated. A significant difference was noticed between E pw and E pTHF , E Dw and E DTHF values, signifying that membranes developed with higher loading of zeolite exhibited remarkable separation selectivity toward water. The E p and E D values ranged between 11.69 and 21.23, and 11.21 and 20.72 kJ/ mol, respectively. All the membranes exhibited positive DH s values, suggesting that the heat of sorption is still dominated by Henry's mode of sorption.