Highest Pervaporation Separation Index Research Articles

Beneficent impact of mixed molecular magnet/neodymium powder for facilitating ethanol dehydration in the pervaporation process

The focus of the study concerned the application of alginate membranes enriched with a mixture of Magnequench Fine Powder (MQFP) and a Molecular Magnet [Fe4(acac)6(Br-mp)2] (MM) in different proportions to improve ethanol dehydration via pervaporation. The paper concentrated on how the combined fillers affected the membranes ability to transport the ethanol/water solution components. It was observed that the integration of MM into MQFP not only improved the magnetic properties but also provided a uniform distribution of the filler in the alginate matrix. By merging the properties of two different fillers, we achieved membranes with outstanding separation process performance. This efficiency was unattainable using each filler separately, highlighting the synergistic effect of combining the two fillers. The membrane with 1 wt% MQFP and 9 wt% MM proved to be the most efficient, with the highest Pervaporation Separation Index and separation factor, reaching 40974 kg⋅m−2⋅h−1 and 12735.14, respectively.

High flux and ultra‐thin poly‐dimethyldiethoxysilane/poly(vinylidene fluoride) composite membrane for alcohols recovery from aqueous solution by pervaporation

AbstractPervaporation (PV) of membrane separation technology has become an efficient approach to separate alcohols from aqueous solution. In this study, focusing on increasing the total flux and breaking the trade‐off in PV, an ultra‐thin and high flux poly‐dimethyldiethoxysilane (PDMDES)/poly(vinylidene fluoride) (PVDF) composite membrane was prepared. By employing various means, the characterizations of PDMDES/PVDF composite membrane were extensively investigated and the promising results indicated the high hydrophobicity and good affinity to alcohols. To be specific, PDMDES selective layer with different thicknesses, the thinnest of which was approximately 265 nm, were fabricated, and better PV performance can be achieved in a thickness range of 1.10 ~ 1.69 μm. The optimal PV performance of PDMDES/PVDF composite membrane was obtained in separating methanol from 5 wt% methanol/water solution at 40°C, resulting in a total high permeation flux of 5.38 kg m−2 h−1 and a higher pervaporation separation index (PSI) of 18.63 kg m−2 h−1.Highlights The ultra‐thin and high flux composite membranes for alcohols recovery via pervaporation (PV) are prepared by using monomer in membrane preparation through a simple fabrication method. The trade‐off is broken in the ultra‐thin composite membrane compared with traditional composite membrane. The influence between membrane thickness and PV performance is investigated through experimental tests, and the results show that the ultra‐thin composite membrane has a total high permeation flux of 5.38 kg m−2 h−1.

Studies on sorption kinetics and sorption isotherm for pervaporative separation of benzene from model pyrolysis gasoline using insitu nano silver/polyvinyl alcohol membrane

Pyrolysis gasoline (Py gas) is used as an octane enhancer of gasoline as it is rich in aromatics. However, removal of carcinogenic benzene from Py gas before blending with gasoline is important to meet the fuel specifications. The main focus of this present study is to determine the sorption kinetics and sorption isotherm of a fabricated insitu nano silver/polyvinyl alcohol (insitu nano Ag/PVA) membrane for pervaporative separation of benzene from model Py gas [mixture of benzene (aromatic) and 1-octene (aliphatic)]. The thickness, surface morphological structure (Atomic Force Microscopy) and degree of swelling of the fabricated membrane were determined. The highest pervaporation separation index achieved for the selected system was 14.259 kg/m2/h at 303 K, with 30 volume% benzene in model Py gas using a downstream pressure of 1 mm of Hg. The sorption kinetics of benzene in insitu nano Ag/PVA membrane obeyed the Elovich model while the Temkin isotherm model fitted the experimental data of the chosen system most accurately.

A high ZIF-8 loading PVA mixed matrix membrane on alumina hollow fiber with enhanced ethanol dehydration

In this work, a zeolitic imidazolate framework-8 (ZIF-8)/polyvinyl alcohol (PVA) mixed matrix membrane (MMM) was coated onto α-aluminum oxide (α-Al2O3) hollow fibers for ethanol dehydration by utilizing the pervaporation technique. ZIF-8/PVA solution was prepared via a drying-free, water-based method to obtain a uniform distribution MMM. Before coating the MMM onto the hollow fiber, a pristine PVA solution was first dip-coated onto hollow fiber as a gutter layer to prevent phase separation. Different weight ratios of ZIF-8-loaded MMMs were prepared. The results showed that at high ZIF-8 loading (39 wt %), a high permeate flux (685 g/m2 h) and high separation factor (4821) can be observed. Furthermore, compared with free-standing ZIF-8/PVA MMMs, hollow fiber supported ZIF-8/PVA MMMs exhibit a thinner coating thickness but higher pervaporation separation index (approximately 1.5–2 times). The main contribution of this study is not only fabricated the high loading ZIF-8/PVA composite membrane with enhanced performance, but also coated onto the hollow fiber membrane which opens a gate for scale-up production.

Pervaporation separation of isopropylbenzene from water using four different polymeric membranes: Membrane preparation, modification, characterization, and performance evaluation

In the present study, for the first time, the separation of isopropylbenzene as a volatile organic compound (VOC) from water was investigated through the pervaporation (PV) process. Polyvinylidene fluoride (PVDF), polydimethylsiloxane (PDMS), polyether block amide (PEBA), and ethylene-propylene-diene monomer (EPDM) polymers were utilized in the preparation of PV membranes, and their performance and properties were compared. With respect to the results, the PVDF membranes had the highest PV separation index (PSI) equal to 66,486.6 g/m2h. In addition, this membrane had the highest Young's modulus and tensile strength, together with a low swelling degree. However, it had the lowest water contact angle and thus, was further modified. For this purpose, for the first time, Span 85 was used as an additive in the structure of PV membranes. The membrane characterizations implied the increased hydrophobicity and decreased swelling of the PVDF/Span 85 membrane in comparison with the pure PVDF membrane. The PV results revealed that the addition of 2 wt% Span 85 to the PVDF membrane was followed by an improvement in the separation factor so that it resulted in increased PSI (105,761.9 g/m2h).

Spray‐coatedPDMS/PVDFcomposite membrane for enhanced butanol recovery by pervaporation

AbstractIn this study, spray‐coating was used to prepare dihydroxypolydimethylsiloxane (PDMS) composite membranes with high flux and separation factor for biobutanol recovery from aqueous solution. A thin, smooth, and defect‐free PDMS layer was prepared by spray‐coating on polyvinylidene difluoride ultrafiltration membrane with little PDMS penetration. The effects of process parameters for membrane fabrication and pervaporation on membrane performance were investigated. A membrane with 2 μm active layer was obtained with a high flux of 1306.9 g/m2h. The optimal membrane with the highest pervaporation separation index (PSI) (19.15 kg/m2h) showed a total flux of 530.6 g/m2h and a separation factor of 36.1 at 37°C, and a PSI of 65.61 kg/m2h and a flux of 1927.0 g/m2h at 70°C. Membrane performance was affected by feed composition and temperature. Acetone‐butanol‐ethanol solution and fermentation broth gave lower butanol fluxes and separation factors compared to butanol model solution.

Fast surface crosslinking ceramic hollow fiber pervaporation composite membrane with outstanding separation performance for isopropanol dehydration

A facile fast surface crosslinking method was adopted to fabricate ceramic hollow fiber composite membranes with a thin separation layer for outstanding pervaporation (PV) performance. The morphologies, surface chemical compositions and hydrophilicity of the chitosan (CS)/ceramic hollow fiber composite membranes were characterized by field emission scanning electron microscopy (SEM), X-ray photoelectron analysis (XPS), and water contact angle (CA), respectively. The influences of CS concentration, feed composition and temperature on the membrane performances were investigated systematically. The operation time of the surface crosslinking process was several minutes (i.e., 4 min). The thickness of the separation layer of the obtained composite membranes ranged from 322 to 1414 nm, exhibiting excellent separation performance. The Arrhenius active energy (EJ and ED) and the diffusion coefficient (Dw and DIPA) were calculated to theoretically analyze the membrane separation process. The highest PV separation index (PSI) value was 8.2 × 106, indicating that the obtained membranes possessed enormous potential in IPA dehydration.

Pervaporation properties of oleyl alcohol-filled polydimethylsiloxane membranes for the recovery of phenol from wastewater

In the present work, the modified polydimethylsiloxane (PDMS) membranes incorporated by oleyl alcohol (OA) were prepared for the first time. The polymeric membranes were characterized by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM) before and after modification. These membranes were used for the pervaporative separation of phenol from wastewater. The effects of OA loading and feed temperature on the pervaporation performances have been investigated. The influence of ignoring the partial pressure at the permeate side was compared and discussed. The results showed that the OA presence increased phenol flux and separation factor, and decreased water flux greatly with less than 9 wt% OA loading. The highest pervaporation separation index was obtained with 5 wt% OA loading. The driving force of phenol across the membranes was much lower than that of water, and permeation of phenol was much higher than water in nature. It is necessary to discuss and compare the intrinsic properties of different membranes using permeation and selectivity, even though the membranes are tested under the same feed temperature and concentration. The partial pressure of phenol at the permeation side cannot be simply omitted for its great effect on the permeation. Increasing feed temperature will result in the increase of flux and separation factor, but decrease of permeation.

PERVAPORATIVE INVESTIGATION OF ETHYL ALCOHOL DEHYDRATION

Pervaporative separation properties of crosslinked chitosan and alginate membrane on ethanol-water mixture at room temperature was studied. The influence of crosslinking agents on the separation properties were discussed. Selected crosslinking agents were affected differently on used polymer matrices. The better separation properties were obtained for membranes crosslinked by phosphoric (V) acid. The highest pervaporation separation index (309.6 kg/m 2 ·h) and separation factor (52.6) were obtained for phosphoric (V) acid crosslinked alginate membranes, however, the greatest total flux (12.4 kg/m 2 ·h)

Separation of ethyl acetate–isooctane mixtures by pervaporation and pervaporation-based hybrid methods

The separation of binary ethyl acetate–isooctane mixtures by pervaporation and pervaporation-based hybrid methods is studied in this paper. The potential of pervaporation using commercially available membranes (PolyAn GmbH, Germany) was evaluated experimentally and the effect of the feed concentration and the operating temperature on the separation performance was determined. Only two of the eight tested membranes, i.e. POL_AL_M2 and POL_OL_M2 were found preferentially permeable to ethyl acetate and chemically stable up to 25wt.% of ethyl acetate in isooctane solution, thus restricting the concentration range for which pervaporation can be applied. The POL_OL_M2 membrane combining a maximum separation factor of 22.34 with a total permeate flux of 6.3kg/m2h at 30°C and a feed concentration of 25wt.% ethyl acetate, demonstrated a higher pervaporation separation index (PSI) than the POL_AL_M2 membrane. The obtained retentate was highly concentrated in isooctane (more than 99wt.%) but the permeate reaches an ethyl acetate concentration lower than 90wt.%. As maximal isooctane recovery and full ethyl acetate purification could not be achieved by stand-alone pervaporation using the available membranes, pervaporation-based hybrid processes were considered for both solvents. Because of its higher PSI, the POL_OL_M2 membrane was selected for these hybrid processes, aiming at a higher purity of ethyl acetate enriched permeate and total recovery of both ethyl acetate and isooctane.